Ultra Blak 407
Black Oxide Finish for Stainless Steel
Ultra Blak 407 is a black oxide finish for stainless steel. The oxidizing salts are used at 4.75 pounds per gallon of water at temperatures of 250° to 260° F. The finishes comply with military specification MIL-DTL-13924D Class 4.
The versatile solution may also be used to blacken malleable and cast iron as well as some mild low carbon steels.