Black Phosphate For Do-It-Yourselfers

[Chuck S.]

Over the last couple of years, several members have contacted me about a source for the chemicals used for black and dark gray phosphate finishes on fasteners and other small parts. Until recently, I knew of no commercial source where small quantities of these chemicals could be purchased.

Recently, in preparation for finishing some small fasteners, I did a search on the internet, and was successful in finding a firm that sells these chemicals in small quantities. The primary users are gunsmiths and gun collector/restorers. In the gun business, the phosphate finishing process is called "parkerizing".

Anyone interested in doing their own phosphate finishing can purchase the required chemicals at the website below. I haven't tried the stuff yet (waiting on UPS), but from the descriptions of the solutions, this is the right stuff. They also have Harley Davidson refinishing kits, but they are probably unaware of the classic car market.




Calvan Company Website

[Harmon C.]

Re: Black Phosphate For Do-It-Yourselfers

Chuck My old supply from Carolina Chemco is about gone. What I had was grey and they have black also. Have you tried this product and I wonder if a person could do a mix to get the right shade? Thanks Chuck great tip !!! Lytle

[Kent K.]

Used something like this

About 11-12 years ago, I bought the chemicals from a vendor at Bloomington Gold and used them to refinish hardware that was originally finished black phosphate, if terminology is correct. Intensity of the color is dependent upon time in the bath. It worked great but the odor is not pleasant.
Kent #6201

[Kevin Morris]

Re: Black Phosphate For Do-It-Yourselfers

Great tip Chuck, thx. Is gold anodizing something that can be done at home, as well?

Kevin #39927

[Kevin Morris]

Re: Black Phosphate For Do-It-Yourselfers

Also, what about a source for cadmium?

[Tracy C.]

This Place Looks Promising.......

I recently ordered some buffing supplies from Caswell and asked for their catalog. They seem to have everything a hobbiest/restorer could want.

Their buffing supplies are first rate and I'm very tempted to buy up some of the "home plating kits" to experiment with.

I bombed chemistry, but they seem to make it sound easy enough. The link is below.

tc

http://www.caswellplating.com

[Clem Z.]

cadmium is listed as a carcinogen

so i would not think it would be available to the general public.

[Bob D.]

Re: Black Phosphate For Do-It-Yourselfers

Great tip Chuck. Caswell makes a black phosphate/parkerizing kit that I have used. It works great also.

[Chuck S.]

Re: Black Phosphate For Do-It-Yourselfers

Lyle, you get the "shade" by strength of the diluted solution and immersion time. The dark gray is actually an altogether different chemical (dark gray is zinc phosphate; black is manganese phosphate). Mixing them might not be a good idea. I don't think it would harm anything, but you might not get the results you expect.

I got my original manganese phosphate solution from Carolina Chemco. About 1997, I tried to recontact them for more solution and got that annoying recording that says "I'm sorry...that number is no longer in service." My early internet attempts to re-contact them were also un-successful. I figured the owner had gone on to that great Corvette restoration palace, and for years, I have been telling people that Carolina Chemco was out-of-business.

[Chuck S.]

Re: Black Phosphate For Do-It-Yourselfers

Kevin, I haven't seen any product/kit for gold anodizing, but then I haven't been looking. You have to figure, that if it's available, it would be Caswell's that has it, and that the parts would have to be small. I doubt that it's available, but I would probably do a search anyway.

[Chuck S.]

Re: Black Phosphate For Do-It-Yourselfers

Kevin, Clem's right; To my knowledge, cadmium is NOT available to the public. The only way commercial platers can get the stuff is that they have sophisticated waste treatment facilities on-site to dewater the contaminated sludge and compress it into small volumes for disposal into controlled sites. They couldn't very well let John Q. be flushing the stuff down his toilet. Of course, I'm not saying you should flush ANY of this stuff down the toilet. :-)

As the Reverend Varoom used to say, plain old blue (or clear) zinc plating is indistinguishable from silver cadmium for all intents and purposes. (The Rev used to defy anyone to tell the difference without an electron microscope.) You can also do a dichromate wash on the zinc, and get exactly the same yellow finish that you see on dichromated cadmium. You can get the stuff to do zinc on small parts from Caswell's; I'm not sure about the dichromate. If you have alot of stuff to do, like a complete restoration, it will probably be better to find a commercial plater.

[Chas Kingston]

Electrochemistry

[Chuck S.]

Re: Black Phosphate For Do-It-Yourselfers

Bob, you will notice that Caswell never claims that their "parkerizing" kit is black phosphate. In fact, they describe it as "black oxide", except for stainless, which they describe as a stainless "blackening" kit. Theirs is a cold process, and is probably considerably easier than black phosphate finishing which must be closely temperature controlled.

There are a lot of applications for black oxide on Corvettes, but where you need black or dark gray phosphate, it's the right stuff. When you examine phosphate finished parts in strong light, light will be reflected off millions of little facets, giving it a sort of crystalline appearance. Typical "blackening" finishes cannot duplicate this look.

For judging, however, these simple blackening finishes MAY fly; there simply isn't enough light in many judging situations (indoors or underneath the car) to determine if the crystalline appearance is there. I don't think an ordinary judge's flashlight would be strong enough, but I've never put it to the test.

[Terry M.]

Parker Chemical Co. *TL*

was the company that sold some of the chemicals we used in the metallurgy lab in the late '60s to make grey phosphate coating to trap the lubricant for metal forming work. Their patented process was called Parkerizing. Another company that supplied us was the Hooker Chemical Co. They became associated with a town in New York named Love Canal.
The process we used was a system of fiberglass tanks with steam passing through lead pipes to heat the solutions. It was definitely a hot (in more ways than one) process. I doubt today's laws would allow one to do what we did, the way we did it, even if you could set up this system. One of the tanks was a heated sulfuric acid solution that was distinctly unpleasant to deal with - it did clear the sinuses though.

[Harmon C.]

Re: Black Phosphate For Do-It-Yourselfers

Chuck I bought my Carolina Chemco at Knoxville Expo as the vendor was putting on a demo. I bought a quart and tried to order more and they was gone. My bottle just says phosphating concentrate with no description of what it was. The parkerzing method was printed out as how to use the product. It did sprakle and I thought it was more gray than black. Which product do you think will be best for shark hood latches? Did your old bottle say manganese on it? What I have left has a yellow cast to it and some metals came out black such as the EGR clamp but the latches were too gray for me but had the sparkle. Lyle