What is a Cast Iron Chip Test

Most coolants today are formulated to include rust preventatives. These Rust Inhibitors provide a protective barrier on metal surfaces. The Cast Iron Chip Test (ASTM D4627) is a good indicator of a water soluble product’s rust preventive qualities. ASTM Standard Cast Iron Chips are placed on filter paper and then soaked with approximately 10 mls. of coolant for 4 hrs. If rust spots are present on the filter paper after removal of the chips, the coolant fails. If no rust spots are present the coolant passes. As part of our standardized quality control process we test most coolants for rust inhibition prior to packaging at 3, 4 & 5%. They must pass this test to be approved.