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.