chemical treatments for stainless

[Spike42]

I have several thousand small 304 stainless steel parts and I would like the change the physical appearance of them. I know there are come chemical treatments that you can do on stainless (to turn it black for example) but do not know much about them. Is anyone framiliar with these processes or know of a good resource where I could look up some information? Thanks.

 

[kenvlach]

Hi Spike42,
Black is the only routine color:
hot black oxide process – MIL-DTL-13924D [Note: the Class 1 solution used for mild steel is unsatisfactory for SS, Class 4 will work on 3xx SS]
electroplated black chrome – MIL-C-14538D
electroplated black nickel – no MIL spec, can be very glossy over bright nickel plating.
MIL specs are available at ASSIST:

http://assist1.daps.dla.mil/quicksearch/

The room temperature blackening solutions that I have tried didn’t work on SS (wiped off), but possibly improved products are available. See
Blackening
thread798-86272

Interference colors (which vary with thickness & viewing angle) can be produced by anodizing SS. There are maybe 2 companies in the US which do this; check the

http://www.finishing.com

site.

Oxidation by heating to various temperature in air (“heat treat tint”) will produce shades of yellow, blue and purple. This is a combination of interference coloring and doping. The contact points will not color as well, so you cannot do a basket of flat parts like washers, and other parts require some in-process motion. Ask your local heat treater & do some experimentation. Note that thicker coatings become porous and flaky. See
Heat tint of stainless steels
thread725-25564

Of course, you can electrodeposit copper, which allows a variety of finishes: blue-green, copper, brass, antique brown, etc.

TiN deposited via PVD gives the gold color commonly used on twist drills. Gold, rose gold, rose copper, brass, brown, bronze, black or charcoal grey also available; see

http://www.pacificplus.com/specs.htm

 

[pennpoint]

Spike42
You did not specify what type of finish you really wanted.
You can also have those parts electropolished to a nice bright natural SST finish. The cost may be less than black.
A call to your local plater, chrome shop, anodizer will get you where you want to be..

Good Luck

pennpoint

 

[cb68]

Hi Spike42

This website might give you a little more information and show you a few options.

http://www.poeton.co.uk/

Best of luck