FAQs & Links

FAQs & Links

After more than fifty years in the business of providing solutions for production challenges, Chem-Trend has addressed a wide range of questions from around the globe and has developed some very strong relationships within industry. Please feel free to explore the answers to some of the more general, and specific, questions and answers to molding related issues and visit the websites of some of the leading associations and publications of the industries that we serve.

Are low or zero VOC release agents available in the market?

There are some concrete release agents that are low or zero VOC. This needs to be investigated when discussing the characteristics and attributes of different release agents with potential suppliers.

Are low/no VOC release agent and other process aid materials available to help meet emission regulations?

This is an area of growing concern and interest and there are products available that have low and zero VOC materials.

Are there additional advantages to using mold cleaners for thermoplastics processing beyond the obvious?

Some engineered polymers have viscosity/MFI which tends to interrupt the passage of air through the mold air venting system. The use of mold cleaners is the best solution to remove the residue polymer in the air venting quickly while in-process, avoiding to the need to remove the mold from the machine to conduct the cleaning.

Are there any lubricants developed specifically for high temperature thermoplastic applications?

Most lubricants used at temperatures above 150°C tend to dry out and their lubrication performance stops. The lubrication effect above that temperature is usually a dry lubrication process which is not suitable for small ejector pins. Specific lubricant formulations have been developed to be used at higher temperature applications.

Are there differences between purge compounds for extrusion and purge compounds for injection molding operation?

Purge compounds for extrusion have a lower MFI compare to those used in injection molding. Injection molding purge compounds need to be able to clean a hotrunner at gate size below 0,4 mm.

Are there suitable release agents for thermoplastic materials that are sensitive to stress cracking?

Materials such as PC and ABS are particularly sensitive to stress cracking. Release agents have been developed that can be used in the production of parts made from these materials.

Are universal purging compounds available that can work with all applications and polymers?

Thermoplastic processing is done in many different ways with many different polymers at a wide range of temperatures. Universal purging compound are available on the market, however they are very compromised offerings that are minimally effective. 

Can a mold release agents cause problems in post molding treatments?

In general, post mold treatment of surfaces can be adversely affected by the residual presence of release agents if the release agent is not compatible with such treatment or if it is present in excess on the released part surface. The choice of release agent chemistries compatible with post release operations, the adjustment of the application level onto the mold and the choice for low transferring release agents (like semi-permanent ones) can lead to successful post molding operations and minimize any part contamination issues.

Can die lubricants contribute to gas porosity in the casting?

Gas porosity can occur when the turbulence of the molten metal traps gas inside the casting. Excess die lubricant can create more gases in the cavity that may contribute to gas porosity. High efficiency die lubricants do not contribute significantly to gas porosity.

Can die lubricants contribute to smoke in a foundry?

The main source of smoke is usually the plunger lubricant. These are usually organic compounds and there is a tendency to overfeed these products. High efficiency and low smoke plunger lubricants can minimize the smoke in a foundry. Die lubricants are usually water-based products and therefore are not major contributors of smoke. Some oil-based die lubricants can produce smoke but are typically fed at very low dosages and so the quantum of smoke produced is not significant.

Can I use the same release for all of my parts, regardless of whether they are gel-coated or not?

While some manufacturers may choose to use one semi-permanent release for all their needs, we believe that gel coated and non-gel coated applications should be handled differently, as should male and female tools. Typical non-gel coated applications such as stringers, require a slicker release agent than a gel-coated tool.

Can machine parameters influence the cleaning result of a purge compound?

Various factors like temperature and application time can have an influence on the cleaning result and need to be taken into consideration when selecting and utilizing a purging compound.

Can mold cleaners remove polyolefins?

Polyolefines cannot be dissolved, however the main issue in trying to clean the mold is usually not the polymer itself but the additives, pigments and paints. These materials can be removed with a mold cleaner.

Can purge compounds be reground and added to the plastic part as recycle content?

The addition of purge compound into the regrind stream for part production is not recommended as it will affect the physical properties of the final part, likely resulting in rejected parts. 

Can purge compounds be reground and reused for future purging?

A purge compound that is contaminated with color, black specks or dissimilar materials has already been saturated or partially saturated with contaminants and will not exhibit the potency of virgin purge compound. Therefore, it should not be reused as it will not produce an efficient purge.

Can purging compounds be used in hot runner systems?

Not all purging compounds are safe for use in hot runner systems; however there are some purging compounds which have been developed to be hot runner safe. The specifications of the manufacturer of the hot runner system should also be noted.

Can silicone containing die lubricants affect the paintability of a casting?

The paintability of a casting is more dependent on the efficiency of the cleaning process. Silicone containing die lubricants can be used to make paintable parts, but they must be easily cleanable by most cleaning processes. Because of the wide variation in the types of cleaning process and the cleaners used, we advise customers to check the efficiency of cleaning before finalizing the product.

Do die lubricants contribute to COD?

COD stands for Chemical Oxygen Demand and all organic compounds create COD. In the case of die lubricants, typically a significant amount of the organic materials can be removed by precipitation or filtration as described above.

Do multifunctional sprays that include some type of corrosion inhibitor offer adequate corrosion protection?

Multifunctional sprays offer temporary protection (usually for up to three months) while pure anticorrosion agents provide more extensive protection (12 – 24 months) and should be used when an extended storage period is expected.

How are release agents best applied?

Depending on the production set up a wide variety of configurations can be utilized. From manual HVLP guns to automated spray systems, assistance with determining the best selection to efficiently apply concrete release agents should be provided by the release agent supplier.

How can anticorrosion agents be removed from a mold or from plastic parts?

Oil-based anticorrosion agents should be removed with a surface cleaner before the production process. Wax-based anticorrosion agents melt at normal mold temperatures and are removed from the mold in the course of regular processing. A separate cleaning procedure for wax based anticorrosion agents is not required.

How can concentrate release agents be most efficiently mixed?

Materials may be diluted through very reliable wall mounted or floor model proportioners. These units provide a consistent water to concentrate ration that allows for a dependable mix without the use of valuable manpower.

How can die lubricants improve my productivity?

Die lubricants that are designed to rapidly cool and adhere to the die surface form a protective film that prevents solder and provides lubricious release of the casting. This can reduce both the cycle time and down time, improving productivity.

How can I ensure the surface is adequately sprayed?

By using a piece of cardboard a spray pattern may be tested. First make sure the spray equipment nozzle and air cap are clean and unrestricted. Hold the spray gun a distance from the cardboard that is a normal distance from the spray gun to the molding surface. Spray the mold release onto the cardboard in a sideways sweeping motion. The pattern should be solid yet dry quickly. Any splotches will show areas that may be under sprayed or unevenly applied. Liquid running down the surface means the liquid is being applied too heavily.

How can I increase bladder life?

The life of tire curing bladders can be increased through the application of a curing bladder treatment, which helps to protect the bladder against chemical and abrasion attack throughout its service life. This type of attack is prevalent at the surface of the curing bladders that contacts with the beads of the tires being cured. Coatings can significantly help increase average bladder life. The choice of inside tire paint can also have a positive impact on the service life of curing bladders.

How can we control the dilution ratio of die lubricants?

The dilution ratio of die lubricants can be checked by using a LaMotte meter. A sample of the dilute die lubricants is placed in the instrument and the reading is compared against a standard calibration curve. Automated systems for checking the dilution automatically are also available.

How do I apply product to a green tire?

Most products for the tire industry are developed for application to green tires using any of the following systems:

  • Spray gun, either automated, e.g. Ilmberger or Plummer units etc., or hand-held spray guns.
  • Paint brush.
  • Sponge or swab.

The actual application technique(s) chosen by any given tire plant depends primarily on the equipment available and the logistics of the particular plant. Experienced release agent suppliers should be able to provide recommendations to improve and optimize application techniques where desired.

How do I deal with rub marks?

Rub marks are typically a result of excess abrasion. Proper preparation of the tool and more frequent touch ups of release should minimize rub marks.

How do I ensure a consistent application from operator to operator?

When applying a release agent with manual spray it is important to establish a baseline throughput to maintain a consistent spray. Required throughput amounts will vary based on the tooling grain, part complexity, and the speed of the line. When a proper spray amount is determined the throughput in grams or milliliters per second should be recorded. This should be checked each shift to make sure there is consistency between operators. This information will help to train new operators to correctly apply the release agent. Consistent fluid and atomizing air pressures are also a must for repeatable application.

How do I know how much product to apply to the tire and how can it be measured?

Generally speaking the optimum coating of inside paint is one that is evenly spread across the entire inner face of the of tire reaching across the tire from bead to bead. For outside paint the coverage should be a thin even film applied to the areas of the tire that benefit most from the use of an outside paint, typically this would be the tire sidewall areas and perhaps an area around the external shoulders. The tread area is often not coated with an outside paint.

Once the optimum coverage is obtained, using the visual guidelines mentioned above then the actual coat weight maybe determined. This may be achieved by either measuring the shot weight or using pre-weighed patches adhered to the inside or outside of the tire, the so called "patch-test". The shot weight may be determined by using pre-weighed polythene bags placed over the spray gun heads to capture the amount emerging from the spray gun head when it is activated. The "patch-test" involves applying pre-weighed patches applied to the inner-liner or outer face of the tire, depending whether one is measuring the volume of inside or outside paint being applied. In the case of the plastic bag technique it is usually best to measure an average of five to six activations of the spray gun to simulate the spraying of five to six tires, and then calculating the average amount in order to obtain better accuracy. In the case of the "patch test" it is better to apply three patches spread around the inside or outside of the tire to help determine the distribution of the film around the tire. In both cases the measured coat weight is obtained from calculating the differences between the pre-weighed empty bags or pre-weighed clean patch, and the weight after the tire is sprayed or the spray cycles simulated, depending on which technique is being used. An experienced release agent supplier should be able to provide support in this process.

How do the specific applications (composite, plastic, rubber, etc.) affect the type of mold release agent recommended?

In general, the release agent should not be chemically compatible with the material being molded: offering a good chemical and physical barrier preventing the molded compound from chemically interacting with the mold (substrate). It is the old adage “like dissolves like”, so if the release agent and material are too compatible, the material can penetrate the release agent film and adhere to the mold surface. The composition of the material being molded, as well physical characteristics like hardness and abrasion (often influenced by fillers and reinforcing agents), influence the choice of release agent. Different metal alloys, thermosets, thermoplastics and elastomeric materials have different molding processes and conditions which demand different requirements from the release agent, affecting mold release selection.

How do you remove material prone to thermal cracking and encrustation from equipment?

Some polymers tend to produce more thermal cracking products and encrustations than others. Special purging compounds have been developed for these polymers.

How does a die lubricant have to be treated in waste water systems?

Water based die lubricants are typically emulsions of oils and other actives in water. The size of the emulsified particles is an important issue. Small particles can be removed in conventional precipitation style waste water systems using alum and lime or similar reagents. They can also be removed by semi-permeable membranes like UF and NF although these may have a tendency to foul (depending on the type of membranes used). The removal efficiency depends on the type of process used.

How long should I wait between when the release agent is applied and pouring polyurethane foam?

The key is to have a dry mold surface before the foam is poured. A liquid carrier is used to deliver the release agent to all surfaces of the tooling. This carrier should be evaporated before the foam is poured or injected into the tool.

How rapidly is the industry moving away from solvent based mold release agents and towards water based mold release agents?

The shift greatly depends on the industry and process requirements. Several industries no longer tolerate solvent-based products due to health, safety and environment concerns or other regulatory issues. Industries such as die casting, tire manufacturing, and general rubber molding use predominantly water based release agents. The polyurethane industry uses both water based and solvent based mold release agents, the composites and thermoplastics industries use mostly solvent based release agents at this time.

Water-based products are more sensitive to application (offering more challenges to film formation) and have slower evaporation rates (which can be influenced by the application method, process conditions and environment humidity levels) than solvent based products. Water-based products are more prone to cause chemical interaction of residual water remaining on the mold surface with the material being molded during the molding process (e.g. generation of urea byproducts in polyurethane molding). This category of release agents also requires more technology to ensure emulsion stability and bio-activity resistance. These challenges have to be addresses to expand the use of water based release agents across a wider range of industries.

How should I remove a semi-permanent mold release?

Removal of semi-permanent releases can be more difficult due to the toughness of the cross-linked coating. The recommended procedure is to use a specially designed cleaner or a buffing compound to ensure that all of the coating is removed.

How should non-aerosol release agent products be applied in thermoplastic processing operations?

Non-aerosol products are best applied in thermoplastic processing using a high quality spray gun or with clock-controlled spraying equipment.

How should the mold release agent applied?

Application methodology depends on the carrier of choice as well as on the nature of the release agent and the process and process environment. Application is a key aspect to be observed and may significantly influence the performance of the release agent. In most cases, release agents are applied using a spray gun (manual or robot application). In some applications programmable spray systems with multiple spray nozzles allowing for the application of one or more release agents are used. The nozzle size is regulated to ensure proper atomization (influenced by the expected throughput and release agent viscosity) and good film formation. Spray application can be air assisted (where air is used to further shear and atomize droplets) or airless (where the nozzle operating at high pressure shears the release agent stream to obtain the necessary atomization). Electrostatic spray guns can also be used to apply solid and liquid release agents. In some applications, release agents can also be applied by aerosols or even through manual or automated wiping.

I get streaking when applying. What should I do?

Many of the same factors that cause hazing also cause streaking. In our experience, streaking that occurs on application of release is most often the result of contamination, entrapped moisture, or improper application techniques. Presuming that the mold was cleaned properly, how you apply the release can have a big impact. Both sealer and release should be applied in a light even coating, using clean 100% cotton cloths. Do not use synthetic cloths because the solvent in the mold release can dissolve this type of cloth and cause streaking. DO NOT REUSE CLOTHS. 

Shop environment and atmospheric conditions can play a major role in aggravating streaking. Hazing can occur when molds are cooler than air temperatures. This can result in condensation being trapped within the mold release coating as it cures.

I see haze on the mold. What causes it and can I get rid of it?

Haze On The Mold After Applying Release (before molding): This can be caused by reaction of the release with contaminants on the mold surface; styrene in the mold blushing to the surface and becoming entrapped; entrapment of moisture in the curing release (particularly in very humid conditions); contaminated application cloths or wipes; condensation (particularly when molds are cooler than air temperature).

Haze That Appears After Molding: Heat as a catalyst can drive moisture, un-reacted styrene or other un-reacted materials up through the mold matrix during the molding process, entrapping them between the mold surface and the semi permanent film. Over several molding cycles the styrene can also polymerize leaving a tenacious film on the mold surface. Compounding is the preferred method of removing this buildup.

I want to convert my molds to a semi-permanent mold release. Do I need to strip them first to do this?

If you are evaluating any mold release, we suggest that you totally strip a test mold and prepare it according to the manufacturer's instructions. This is the only way you can gauge performance and understand the specific application process. When testing any mold release, we always suggest that you select a test mold that is representative of your production, and one that is expendable in the event of a mishap occurring while testing. Always perform a tape test in several areas of the mold to assure that it is clean (tape should adhere well). Similarly, always perform a tape test on several areas of the mold after applying sealer and release (tape should release easier than on a clean surface).

Seasoned Test Mold Previously Prepared with Wax
This includes any kind of liquid wax, paste wax and waxed based sealers. Remove all foreign matter from the mold surface with a high quality mold cleaner and a cotton cloth. We do not recommend applying a semi-permanent directly over waxes, as this will compromise the bond of the semi-permanent mold release to the mold surface.

Seasoned Test Mold Previously Prepared with a Semi-Permanent Release
All semi-permanent mold releases are not the same. Many, however, are compatible with each other, which means one can be directly applied over a cured film of the other without stripping or compounding the mold. Test a small area with a high quality mold cleaner. Next, apply a coat of the new semi-permanent release. If the initial coat is difficult to apply (wets poorly), streaks or behaves unusually, STOP, and strip the mold. If everything appears as usual, follow this procedure for the entire mold.

In what areas of thermoplastic processing are lubricants used?

Lubricants are used in thermoplastic processing mainly for ejector pins, sliders, nozzles and conveyor belts to avoid seizing or blocking of these moving parts.

Is die cooling an important property of a die lubricant?

While die cooling is an intrinsic property of many die lubricants, it is not the most important property. For some applications a lot of cooling may be undesirable as it can adversely affect the filling of the cavity with molten metal. Other applications may involve dies with little or poor internal cooling. For these applications a die lubricants that can cool very efficiently would be desirable.

Is it possible to prevent lubricants for ejector pins from being transferred to demolded parts?

Low quality or non-specialized lubricants are often not thermally stable; the film created by these lubricants can come off the ejector pins and reach the tips of the pins, where the material may be transferred to the parts and end up as a deposit on the demolded part. Thermally stable, special purpose lubricants have been developed for ejector pin applications that will remain on the ejector pins and will not be transferred during processing.

My parts are pre-releasing. What can I do?

Pre-releasing is another issue that has many contributing factors. Mold design, laminate schedule, resin formulation, gel coat formulation, improperly calibrated spray equipment, gel coat cure time, under or over catalization, shop temperature, humidity, and external heat sources - to name a few - can all lead to pre-release. Most semi-permanent mold releases have a lower surface coefficient of friction than conventional paste waxes, which is why they are more often implicated in pre-release. If all factors other than mold release have been addressed, you may be able to reduce the incidence of pre-release by lightly wiping areas where the mold is pre-releasing with a high quality mold cleaner to slightly alter the surface tension. 

What are the advantages and disadvantages of each type of release agent?

Each type of agent has its own particular strengths (S) and limitations (L). Here is a brief overview by type of release agent:

  • Solvent-based release agents:
    • S: Easier to apply. The solvent carrier also helps with the film formation. The evaporation rate can be adjusted based on the solvent blend. The choice of solvent may ease the dissolution / dispersion of the release agent active ingredients.
    • L: Not highly environmentally friendly. Offer higher health (VOC’s) and safety concerns (fire hazards) than non-solvent based products.
  • Water-based release agents:
    • S: Environmentally friendly and presents no fire hazards. May sometimes be dilutable (can be shipped as concentrates). They can be used to cool the die if necessary. May be developed with a level of technology that ensures mold release agent performance equivalent with solvent based release agents.
    • L: Require more complex technology to manufacture. Proper film formation can be more challenging. This category of release agents may be more prone to stability issues and biological attack. Water-based release agents have slower evaporation rates than their solvent based counterparts and may not be appropriate for some room temperature molding operations or operations with short cycle times. Residual water onto the mold may affect molding performance (entrapped steam) or even chemically react with the material being molded. The latter is particularly an issue when molding polyurethane parts.
  • Carrier-free Release Agents:
    • S: Can be applied “as is” due to the absence of carrier. No vapors emission. Less noisy application is observed. Do not require dilution or tank storage. No waste stream.
    • L: Can create a dust hazard if not applied properly. Require special application equipment (often being electrostatic spray guns), which may require expensive investment. The use of carrier-free release agents may also require additional modifications to the molding equipment to ensure thermal balancing of the mold. These factors often limit the application of this category of release agents.
  • Sacrificial Release Agents:
    • S: Easy to apply. Require less application technique and offer more tolerance of work (less dependent on trained operators).
    • L: Tend to build up on the mold if over applied. In general, the release coating is partly transferred to the molded part, which may cause negative side effects on post molding operations (painting, adhesion, etc.) if applied in excess or if the release agent chemistry is not compatible with the post molding operation. If water-based, tend to cool the mold, removing heat & energy from the system (this may represent a disadvantage if the process is not designed for that).
  • Semi-Permanent Release Agents:
    • S: Require significantly lower application frequency than sacrificial release agents because the release agent film lasts for multiple molding cycles (frequency depends on the process conditions). Allow for a more steady and continued production without interruption for release agent application. There is very little transfer to the molded part, which allows for better post molding operations (coating, adhesion). The release agent can be reapplied regularly on the coated mold refreshing the release agent film. This category of release agents provides an excellent combination of chemical and physical barriers, preventing build up and providing the desired release performance.
    • L: Requires more training of operators to ensure the right touch up frequency is observed. Molds need to be clean to allow for good interaction between the release agent and the mold surface during the initial application of the release agent.
  • Internal Mold Release Agents:
    • S: Reduce the need for external mold release agents.
    • L: May continue to exude to the surface over time compromising post molding operations (coating and adhesion) or the surface cosmetics of the part. Often do not eliminate the need for external releasants as the internal mold release agents do not always migrate to the mold interface or may not ensure 100% release efficiency. Limited in their capability of performing high performance release agent functions such as affecting part surface characteristics.

What are the advantages and disadvantages of silicone-free versus silicone-containing release agents?

The advantage of silicone-containing release agents is that they offer a very good release effect. The disadvantage of silicone-containing release agents is that the subsequent treatment of the released parts, such as gluing or painting, may be difficult or even impossible. Additional post molding part processing will be required.

What are the advantages and disadvantages of the different types of anticorrosion agents?

Oil-based anticorrosion agents can enter tiny and difficult-to-access spaces, such as recesses and undercuts. They dispel moisture and form a temporary protective layer which can last for several months. Wax-based anticorrosion agents provide a stable, long-lasting protective layer and are creep resistant; however they may result in an inclusion of moisture, which is why the surface should be dry before application. Wax-based films tend to protect surfaces for longer than oil-based agents. Wax-based agents form a “dry” film on surfaces, are easier to remove and will not contaminate plastic parts.

What are the different types of purging compounds available in the market?

There are two major classes of purging compounds in the market. One is referred to as Mechanical or Abrasive purging compounds – these are compounds where the cleaning process is based on the mechanical action of hard particles, e.g. glass. The other type of purging compounds are Chemical purging compounds – with these the cleaning process relies on chemical additives that initiate some form of chemical reaction. Purging compounds can come in a ready-to-use format where the product can be used directly from the container or in a concentrate format which requires mixing before use.

What are the key factors in selecting a proper mold release for the task?

Key selection factors are:

  • Type of foam being produced (rigid, seating, RIM, etc.)
  • Molding temperature range
  • Mold material (aluminum, steel, etc.)
  • Time between mold release application and foam pour
  • Cure time
  • Foam density
  • Post molding requirements (bonding, painting, etc.)

The more information on the process the easier it is to determine the perfect release agent.

What are the main functions of a mold release agent?

Mold release agents provide not only a physical and/or chemical barrier as the means of separation between the material being molded and the mold surface, but also impact process characteristics like the flow rate of the material being molded within the mold cavity, molding cycle time and, of course, release ease. The choice of mold release agents also affects finish characteristics of the released part like gloss level, accurate texture reproduction, post molding operations (e.g. adhesion or coating of the molded part) in addition to influencing the mold service life in between maintenance cycles, and overall productivity.

What are the major benefits of a release agent for concrete molding?

Obviously enabling the easy removal of cured parts from different molded materials is an important reason for using a release agent. What many do not consider is that these same materials can greatly increase mold life by maintaining a lubricious film on the mold surface that will prevent the cured concrete from deteriorating the interface. These products can also aid in the wetting out of pigments and improve color transfer from the mold substrate to the stone. This can help to minimize scrap caused by color changes. All of these benefits result in a more efficient operation.

What are the respective advantages and disadvantages of the different types of purging compounds?

Abrasive purging compounds can be economical to utilize, and are efficient for certain situations but they can damage worm and cylinders. As well, they are not universally usable, for example they cannot be used in hot runner systems.

Chemical-based purging compound tend to be milder than abrasive purging compounds, making them safer for equipment, they are universally usable in hot runner systems, can be injected in cavity and are economical in use. However, they require a polymer matrix which is not always compatible with other polymers. 

Purging compounds in the concentrate form can, in principle, be mixed with all polymers universally, but they tend to be more expensive, require time-consuming preparation and create the potential for risk of incorrect dosage. In case of concentrated powders there is also the issue of contamination of conveyor systems and dust loading. Ready-to-use purging compounds are easy to use, there is no risk of incorrect dosage, but they require a polymer matrix which is not always compatible with other polymers.

Abrasive purging compounds can be economical to utilize, and are efficient for certain situations but they can damage worm and cylinders. As well, they are not universally usable, for example they cannot be used in hot runner systems.

Chemical-based purging compound tend to be milder than abrasive purging compounds, making them safer for equipment, they are universally usable in hot runner systems, can be injected in cavity and are economical in use. However, they require a polymer matrix which is not always compatible with other polymers. 

Purging compounds in the concentrate form can, in principle, be mixed with all polymers universally, but they tend to be more expensive, require time-consuming preparation and create the potential for risk of incorrect dosage. In case of concentrated powders there is also the issue of contamination of conveyor systems and dust loading. Ready-to-use purging compounds are easy to use, there is no risk of incorrect dosage, but they require a polymer matrix which is not always compatible with other polymers.

What do I do if an area is sticking?

First, evaluate the area that is sticking. Perform a tape test in various spots on the mold to determine if the problem is related to application. Is it a consistent problem in one area or in one mold? Perhaps the sticking is related to abrasion, sheer edges, or draft angles. Is the area that is sticking a difficult area to reach when applying mold release? It may also be an area that simply requires more frequent touch ups of release, such as sheer edges or other areas of abrasion.

What factors need to be considered in selecting a mold release agent?

Factors to be considered for selecting the proper release agent include:

  • Mold material / substrate
  • Material being molded
  • Process conditions:
    • Temperature
    • Line speed / cycle time
    • Pressure
    • Specific molding process such as injection molding, high pressure, gravity fill, compression, etc.
    • Process variable fluctuations
  • Geometry of the mold
  • Post molding operations (adhesion, coating)
  • Expected performance level and productivity (number of good releases or good parts demolded per time period)
  • Existing process issues (cavity filling challenges, soldering, release-related scrap rates, process condition fluctuations etc.)
  • Mold maintenance expectations (mold cleaning frequency)
  • Part finish requirements (gloss, marring, etc.)
  • Application methodology
  • Health Safety and Environmental (HSE) requirements

What happens if too much release agent is applied?

Applying too much release agent can make subsequent process treatment of the parts more difficult by creating an oily or slick surface on the molded part.

What is a hybrid release agent?

Hybrid products provide the benefits of a solvent based material, such as an open surface and faster film formation and evaporation, but they utilize a waterborne carrier with a small amount of solvent to provide these benefits. This technology significantly minimizes VOC emissions.

What is Inside Tire Paint and why is it used?

Inside tire paints are applied to the inner-liner of uncured tires to provide the necessary slip required to allow the curing bladder (membrane) to locate easily inside the uncured tire during the shaping process of the curing cycle. High slip at this point of the process aids the bladder to conform to the contour of the inside of the tire, thus ensuring a well-centered tire. These paints also assist in the elimination of trapped air. Their use is important in ensuring minimal curing defect levels and optimum tire uniformity. At the end of the curing cycle inside tire paints provide the effective release needed to remove the tire from the bladder.

What is Outside Tire Paint and why is it used?

An outside tire paint is a coating applied to the outside of each tire to ensure any air trapped between the tire surface and the mold surface can escape, this helps assure good rubber flow during the molding process. These paints also help to provide a uniform external tire appearance.

What is the advantage of using release agents from aerosol cans instead of non-aerosol products in thermoplastic processing operations?

The advantage of aerosol cans for thermoplastic processing is that the spray valve system allows the product to be applied very thin, consistently and with a predictable spray pattern. This allows material to be saved and prevents over application. Spray cans also offer easy handling and flexibility.

What is the best Inside Paint for my tire process/plant?

This is a difficult question to answer to provide a definitive answer to because it depends on the type of tires being cured, the equipment they are being cured on and the application equipment available. The best product can only be determined by a thorough assessment and is best answered in consultation with an experienced release agent supplier.

What is the difference between a bladder treatment and a "bladder start-up lubricant or coating"?

A bladder treatment is a special coating that is applied to a new bladder before it is fitted into a press and once cured onto its surface is designed to last the life of the bladder; its function is to protect the bladder against chemical and abrasive attack during its service life, this leads to an increased bladder life.

A bladder "start-up lubricant" is a coating that is applied to a new curing bladder prior to it being installed in a press to help provide additional slip to reduce slip related defects during the first few tires cured on it. Typically these "start-up lubricants" will survive on the surface of the bladder for a limited amount of cycles; however, they do not provide any protection against chemical and abrasive attack.

What is the difference between a Filled and an Unfilled Inside Paint?

A filled inside tire paint contains specially selected fillers. An unfilled inside paint does not contain any fillers.

What is the difference between a mold cleaner and a degreaser or surface cleaner for thermoplastics processing?

Mold cleaners work by dissolving all polymers with the exception of PE and PP while surface cleaners and degreasers work by removing the build-up of materials such as oils, waxes and pastes.

What is the difference between single release and multiple release (durable) Inside Tire Paints?

A single release inside tire paint is applied to the inside of each tire prior to it being cured. A durable inside tire paint is applied to the inside of one tire prior to it being cured; the film is designed to transfer from the treated tire to the surface of the curing bladder during its curing cycle. The transferred film forms a layer on the bladder that has sufficient slip and release to permit the curing of several tires before the film requires replenishment via the curing of another coated tire.

What is the impact of mold release agent buildup on surfaces?

Buildup of release agents, the material being molded, or byproducts and residues generated by chemical reactions that take place within the mold cavity (in situations where the compound is chemically being changed along the molding process) negatively affect molding performance in terms of heat transfer, part dimensional properties, cosmetic appearance and process efficiency. Mold cavity fouling needs to be regularly removed mechanically or chemically to ensure part quality. Every time the mold needs to be cleaned on-site or otherwise maintained, productivity is lost.

Build up issues can be created by two primary sources:

  • Excess of release agent present on the mold. This may be the result of a poor choice of release agent for the specific application (e.g. not compatible with the process temperature) or over application of the release agent onto the mold.
  • Lack of release barrier causing build-up of the material being molded or byproducts and residues generated during the molding process. In this case, the choice of release agent may not be adequate for the process conditions (not suitable for the process temperature, poor film formation, etc.). This may also be caused by application deficiencies (not enough release agent film present on the mold) or lack of physical and/ or chemical resistance of the release agent to the material which then penetrates the release agent film and physically or chemically adheres to the mold.

What is the optimal dilution ratio?

There is no one optimal ratio; this has to be established for every machine and application. The ideal dilution ratio is one that provides the right amount of lubricant film in the shortest spray time possible.

What is the recommended quality of dilution water to be used with die lubricants?

We suggest using soft water for diluting water-based die lubricants. Water with up to 100 ppm of total hardness has been used with no adverse effects. Very pure water (less than 10 ppm hardness) can lead to corrosion problems on the die, while high hardness water can lead to other problems like spray nozzle plugging and in cavity build-up. Using good quality water can reduce downtime and give better quality castings.

What is the recommended spray equipment for release agents?

Various release agents can be used with many forms of spray equipment. While HVLP systems are the most common method of application, many other methods can be used based on equipment and plant configurations.

What kind of dilution system is recommended?

Typically plants use either a centralized system (which serve a number of machines), or individual dilution tanks which are dedicated to one die cast machine. Centralized systems simplify the task of making dilutions and can save cost of equipment. The disadvantage is that if different die cast machines have different operating conditions, it will be difficult to change the dilution ratio or the die lube. Individual dilution tanks allow very tight control of dilution and are preferred when part quality is of very high importance.

What mold prep should I follow after a fast patch? Sometimes I need to put the mold back in production within one hour.

A lot depends upon the material you are using to patch the mold, how thoroughly the patch material cures, as well as the depth and overall size of the patch. Quick set, talc filled, styrene free, BPO cured putties have advantages in these applications even though they must be over-sprayed with gel coat for a cosmetic finish.

(HELPFUL HINT): Some people find that drilling some small negative draft holes down in the laminate area surrounding the area to be patched helps lock the patch to the mold and reduces the incidence of pull out during the seasoning of the patched area. 

Once the patched area has been cured, compounded and buffed, all foreign matter should be removed from the surface using a high quality mold cleaner. Follow this by applying a high quality sealer and release agent following the manufacturer's instructions. 

What positive effects on production do purging compounds provide?

A well-selected purging compound that matches with your process and polymer can provide extensive production benefits such as: time savings (shorter color and material change-over times), material savings, fewer rejects, lower scrap, higher productivity and quality, positive long-term effects on machine cleaning and less wear and tear on machine components.

What prep should I follow after buffing, sanding, or stripping the mold?

Sanding, heavy buffing and stripping can open pores of a mold, allowing un-reacted styrene to bleed out of the mold during production. This can occur in seasoned molds as well. Once the mold has been buffed, sanded, or stripped, and all foreign matter removed, clean the mold with a high quality mold cleaner following the recommended application procedure. Then apply a high quality sealer and release agent following the manufacturer's instructions.

What process aids are available to assist with difficult areas or damaged tooling?

Paste waxes provide an excellent barrier for starting up on clean molds. These materials provide protection in scratched, cold, or high pressure areas, and provide a durable layer that will help to minimize complications due to defects on the metal surface. Mold sealers improve the performance of the release agent by creating an optimal surface to release the parts from. Sealers are applied only to freshly cleaned tools but the benefit lasts throughout the production and cleaning cycle.

What should I do if raw (un-catalyzed) resin or gel coat over-spray gets on the mold?

Gel Coat Over-Spray: Gel coat over-spray has been catalyzed. Even if the film over-sprayed on the mold is thin, it will eventually get hard. If the over-spray has not cured it can usually be wiped off with a cloth dampened with a high quality mold cleaner and then followed by a re-application of mold release. If the over-spray has cured, and the mold has release agent on it, it can sometimes be wiped off with a cloth saturated with a high quality mold cleaner and then followed with a re-application of the release. Or, simply let it totally cure and just peel it off the mold surface. If the mold surface has no release on it and the over-spray cures, in most cases it must be compounded off.

Raw or un-catalyzed resin: Dampen a cloth with a high quality mold cleaner and wipe the raw resin off the mold surface. Use as little mold cleaner as possible and as little pressure in removal as possible to avoid removing an excessive amount of release from the mold. However, you must ensure that you totally remove the un-catalyzed resin from the mold surface; since a thin uncured film of resin could lead to problems on the next de-molding. Having removed all of the uncured resin from the mold surface, reapply mold release and continue processing.

What technical trends are impacting the types of mold release agents offered for various end uses?

Industries are molding more exotic materials to produce parts with better performance under increasingly demanding conditions in which the finished products operate. These exotic materials are not always easy to mold. One good example comes from the automotive sector, where engine components (molded parts) are subject to chemical and physical challenges to withstand more aggressive operating conditions. As a result, newly developed, tougher materials (like fluoro-polymer based compounds), are required to be molded at high production rates with minimal scrap levels (given their higher unit formulation cost). This poses a challenge to the release agent industry, due to their chemical and physical properties which make them difficult to mold and release.

Part appearance has also become more demanding, and in many cases the parts are being used as molded with very minimal subsequent finishing done to the parts. The automotive industry requires that highly visible components like steering wheels or dashboards have exacting cosmetic properties (e.g. texture, gloss and marring resistance) directly following release.

In recent years high-pressure aluminum die casting has seen an increase in the complexity of the molds, with an increase in high integrity (semi-solid and squeeze) casting, as well as a reduction in cycle times and further increasing die temperatures. These factors require the release agent to provide improved anti-solder properties as well as better release and lubrication properties to produce quality parts under the more difficult casting conditions. This has to be achieved without compromising on other performance attributes of the release agent.

More complex and sophisticated mold designs are created for other industries as well, such as the low profile tires made by tire manufacturers. These mold designs place higher performance demands on the release agents with regard to release ease and rubber flow. The post molding appearance of tires is also critically important as well, resulting in significant challenges to easily release these types of tires while also achieving high appearance standards.

The use of lower VOC (volatile organic compound) products continues to be enforced by manufacturing facilities as a result of HSE regulations, being particularly important in processes that require higher direct involvement of operators, like in the composite segment. There will continue to be increased focus on developing products that are more environmental friendly and safer to use. This will stimulate new release agent develop to meet these needs while still providing the same, or greater, level of performance of the products currently in use.

What types of mold release agents carry out these functions?

Release agents can be categorized in a variety of different ways. Here are a few examples of possible categorizations, and how they relate to the functions of high performance release agents:

Based on the type of carrier:

  • Solvent-based release agents: The active principle(s) of the release agent formulation are dissolved or dispersed in a solvent or blend of solvents.  The choice of solvent influences the dispersion quality, film formation and evaporation rate. This category of release agents lends itself not only to heated molds, but also to room temperature application.
  • Water-based release agents: The release agent active components are emulsified into water as the active compounds generally are not water soluble. This category of release agent is more environmentally friendly due to having reduced or no VOC’s (volatile organic compounds). However, technology and manufacturing techniques are more complex in order to provide a stable emulsion and good film formation particularly at room temperature. Often times this category of release agent is presented in a form that can be diluted. Water-based release agents are also required to be biologically stable /robust.  
  • Carrier-free release agents: These are usually solid release agents in powder form. Application is often done using an electrostatic spray gun. Film is formed upon contact with the heated surface similar to powder coatings. 

Based on how the mold release agent (MRA) interacts with the process:

  • Sacrificial Release Agents: This category of release agent is applied in every molding cycle. The release agent film on the mold surface is in great part depleted after each molding cycle and needs to be replenished.
  • Semi-Permanent Release Agents: This category of release agent is reactive with the mold surface, chemically adhering to it whereas it also provides a chemical and physical release barrier. Once applied onto the mold, semi-permanent release agents allow for multiple molding cycles before the release agent has to be reapplied to the mold.
  • Internal Mold release agents: These are specialty chemicals which are embedded into the material being molded. Because they are generally chemically incompatible with the material, they tend to exude to the surface of the part during the molding process providing a release layer. Sometimes the release agent migration mechanism to the surface can also be accelerated by heat.

When/Why would you use a Bladder Treatment or a Bladder Start-up Lubricant?

A bladder treatment is used when there is a specific objective to increase bladder life, especially where sulphur cracking is seen as an issue to overcome. Bladder treatments also assist in providing an underlying layer of slip that helps to reduce defects throughout the life of a curing bladder.

A bladder "start-up lubricant" is used as a general purpose aid to the start-up of new bladders, they help ensure good slip to help a new, and therefore stiffer, bladder comply to the contours of the inside of a tire, thus minimizing defects for the vital first few tires cured. However, they do not offer protection against chemical or abrasive attack, so their use does not lead to higher average bladder life in the way bladder treatments do.

Where are anticorrosion agents used in thermoplastic processing and what are their affects?

Anticorrosion agents are used wherever metallic surfaces have to be protected from corrosion and oxidation which has a negative influence on the part being produced and destroys the surface of the molds and tooling. Anticorrosion agents are used to keep molds and tools in their best operating condition, even while being kept in storage.

Why are some anticorrosion agents pigmented or stained?

Stained or pigmented anticorrosion agents are used to make the application process easier and less wasteful. The stained or pigmented anticorrosion agents are more visible on the mold surface during the application process and therefore allow for more exacting coverage with less waste.

Why do I get buildup and sticking in non-skid areas of the mold?

By taking a few precautions, you can achieve the same production from these types of surfaces as from a polished smooth surface. Buildup in non-skid areas generally can be seen as the same color as the spray-up gel coat. The cause of buildup in the grooves of the pattern usually result from either: 1) failure to apply the release into the tips of deep recesses in the pattern which causes small bits of gel coat or resin to bond in the tips with each cycle, or 2) excess release agent pooling in these areas because of poor application technique. When excess release is present, it does not have a chance to dry or cure thoroughly, or to develop full chemical resistance. The release films over on the surface and can attract free styrene from the gel coat or resin used to mold parts. This can occur because styrene in the resin acts as a solvent, penetrating the heavier areas of release and accelerating the buildup and sticking in these areas. To reduce the buildup and sticking concerns, care should be taken to thoroughly brush out and polish the release into these deep patterns without leaving a heavy residue.

Why do waxed-based anticorrosion agents provide for a better cost/benefit option than oil-based?

Wax-based anticorrosion agents save time at the restart of production with a mold because the agent dispenses during the process and manual cleaning of the mold surface cavity is not required. As well, a wax-based agent reduces scrap due to the fast absorption of the agent.

Why does the automotive industry almost exclusively use silicone-free release agents on thermoplastic components?

Since thermoplastic based parts produced for the automotive industry generally have to be treated further, it is important to ensure that silicone-free release agents are used. Silicone based release agents will cause the surface of interior parts to seem oily, and silicone is difficult to remove from the plastic surface. The risk of paint shop contamination is also very high and silicone can shut down an automotive manufacturing paint shop fairly easily causing production delays and incurring significant expense.

Why is the use of specialized purging compounds important?

A lot of different polymers are used in thermoplastic processing. The color change operation can be a time and material intensive process, especially in situations where hot runner manifolds are involved. A purge compound specialized for the operating parameters and materials being processed can help to reduce the amount of time and material required to clean the machine tremendously. Specific purge compounds provide maximum performance. Optimal change-over performance can only be achieved with the right purging compound as different polymers are not compatible to each other and the use of an incorrect purge compound may create a material contamination situation.

Why should I use a mold treatment and which one is best for my plant?

Tire mold treatments are applied to the surface of tire molds to help minimize mold fouling, aid rubber flow, assist in the release of the tire from the mold at the end of the cure cycle and to enhance finished tire appearance.

The choice of mold treatment depends on several factors, including the desired application frequency, the main reasons for why the coating is being applied, e.g. to improve release from the mold and/or improve finished tire appearance, and the application equipment, etc. Due to the many variables influencing the affectivity of the mold treatment and the desired outcome the best product can only be determined by a thorough assessment and is best answered in consultation with an experienced release agent supplier.

Why would you utilize a single release, or a durable (multiple release), Inside Paint?

A single release inside tire paint is particularly useful when curing tires with complicated contours like ultra-high performance tires, where the low profile and square shoulders create the likelihood of trapped air. In these cases a specialist filled inside tire paint applied to each tire is required. Durable inside tire paints are preferred with tires having less complex contours and in regions where labor costs are high.

Why would you utilize an Unfilled, or a Filled, Inside Tire Paint?

A filled inside tire paint contains specially selected fillers, like mica, to help provide the air-bleed necessary to allow any air that becomes trapped between the tire and the curing bladder to escape. An unfilled inside paint does not contain any filler and is used to obtain optimum finished tire appearance, air-bleed comes solely from the venting pattern on the curing bladder when using an unfilled inside tire paint.

Will release agents affect the color of the stone?

Release agents for veneer/masonry stone applications and other specific concrete applications should be designed to allow pigments to wet out on the surface and to keep molds clean through improved color transfer. Maintaining a proper application amount and/or dilution is important in achieving these goals and the effectiveness of the release agent should be fully evaluated in a field trial prior to full scale adoption.