Class 4 Alkaline Oxidizing. For 300 series corrosion resistant steel alloys only. Coatings shall be continuous free from powdery areas, breaks, scratches, etc. Sometimes called yellow iridite No dimensional change are effected with Iridite finishes. Class 3 is used as a corrosion preventive film for electrical and electronic applications, where low resistance contacts are required.
Coating has no abrasion resistance.
Used to impart black color to and for gloss reduction purposes on copper alloy surfaces other than food service and water supply items. Also as a base for subsequent coatings such as lacquer, varnish, oil, and wax. No dimensional change are effected with Chemical Finish finishes. Has low coefficient of friction, and is resistant to heat. In addition to above properties, can be rendered porous for lubrication purposes.