Letter 19059

Dye Passivation on Steel  

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I am looking for a good process for colors on steel. Prismatic has some colors for steel, but I am looking at a more simple method like dye passivation. Alas, I don't know enough about either of them. Are they both the same process? I would like to know more about Dye Passivation, and its durability. I intend to use it to coat spoons, forks etc. Is it safe?

Thanks, regards,

Vikrant Choksy
- Mumbai, India

Sir,

I have never heard of 'dye passivation,' an earlier inquiry (Letter # 13285) went unanswered, and it is not listed in standard metal finishing references. Traditional passivation of stainless steel leaves an extremely thin, colorless and invisible oxide film on the metal.

I know of no standard coloring process for stainless or other steel that is suitable for food utensils. Gold and platinum plating, and possibly some high-tech processes such as plasma deposition or physical vapor deposition, would work. Coloration can be produced by heating in air, but it is microscopically porous and is normally removed by 'pickling' in strong acids.

Most dyes used in metal finishing are considered toxic. In the past (1950's and 1960's), a few items such as cups were produced in the USA in various colors of anodized aluminum; presently, I am aware of only exteriors of pots, pans, etc. being dyed. Should you consider using anodized aluminum, check with your dye supplier/manufacturer for the toxicity of any particular dye and solutions used for sealing the dyed surface.

Ken Vlach - Goleta, California

Dear sir,

Thank you for your valuable inputs. I appreciate the help and wish you best of luck.

Vikrant Choksy
- Mumbai, India

I am also searching for a way to color a cast 17-4 Stainless steel. Is there a way to add colorant or introduce a different color metal to the melt? Another responder referred to a Vapor deposition coating. Does this offer a solution for colors? Any input would be appreciated

Greg Schmidt
- Phoenix, AZ, USA

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