Black Phosphate

[John D.]

I recall hearing that if you dip zinc plated bolts or nuts in phosphoric acid they turn to a black phosphate coating. Anyone know if this works and/or the procedure?

Thanks in advance

[Chuck S.]

Re: Black Phosphate

No, it won't work, but nice try John.

I've dipped parts in phosphoric acid to clean them for black phosphate coating, and don't recall them ever turning black. Now, if you put phosphoric acid on aluminum, I believe the part will turn black unless you rinse it quickly...it's called "****".

[Barbara S.]

Question about Black Phosphate

Is there a way to plate black phosphate at home, or am I stuck with the platers??

[Chuck S.]

Re: Black Phosphate Edit

Sorry John...After re-reading your post, I realized you were asking about "zinc plated" parts. I take back what I said...I have never tried putting zinc plated parts in phosphoric acid. I have dipped bare steel parts in phosphoric acid, but only as a rinse...This was after I had stripped the old plating using muriatic acid.

Depending on the strength of the phosphoric acid, I would think the phosphoric acid would eventually strip the plating. Even if it works, I don't think you would have an authentic black phosphate finish...maybe just "blackened" parts. ALTHOUGH...one of the solutions used for phosphate finishing is zinc phosphate. It gives you a light to medium gray phosphate finish. It might be worth a try.

[Chuck S.]

Re: Question about Black Phosphate

Not stuck with platers if you have a capacity for tedious bs. (I guess we all do to some extent, or we wouldn't be doing this!)

Do a search of the archives; the most recent threads were discussing new sources discovered for the required chemicals. There is also a detailed DIY article in an old issue of the Corvette Restorer...I forget the season, year, number, etc. Click on "Publications" at the left top of the thread index page, and then click on "Article Index Search".

Unless you've been in NCRS since Moses was a boy, you will probably have to buy the CDs to get the article; But, not to worry...the old articles are an interesting read for restorers and can be worth their weight in gold.

[Jean C.]

Re: Black Phosphate

Although not a black phosphate plating, you can go the route of using gun bluing on steel to get a black finish. Resulting finish lacks the sparkle that I understand proper black phosphate is suppose to have. I am not sure that the zinc coating would allow the cold blue process to work to a black finish.
Best regards,
Charlie

[Travis Williamson]

Re: Black Phosphate

John,

Eastwood has a metal blackening kit, see the link below. Ive never tried it and I am not sure if it would work on zinc. But it might be an option for you.

Good Luck
Travis




http://www.eastwood.com/shopping/product/detailmai

[Barbara S.]

Re: Question about Black Phosphate

Chuck: I found and read your article. You have more patience than I do. I guess I'm stuck with the platers...

Thanks though.
Tony

[kelly theaker]

Re: Black Phosphate

i have a product that does black phosphate , and yes it is close . dont ask what the chemical is but i used it on my resto and worked excellent. give me some mail and get you in the go . I am in Toronto .

[Greg L.]

Re: Black Phosphate

John, Do a Google search for Parkerizing and I think you will find what you need. Parkerizing is how they used to finish some guns way back and it is another name for phosphate. Many of the US gun stores sell the solutions for grey and black phosphate. Hope you don't live in Canada cause you will be SOL for getting it shipped up here...driving it across is no problem though.

[Mike M.]

Maybe Caswell

take a look at Caswell plating systems . mike

http://www.caswellplating.com/

[Kenneth S.]

Re: Black Phosphate

I used the Eastwood kit, it works fine. After you blacken the item you spray it with the sealer that comes in the kit. The trick is to let the sealer dry good.
Ken

[Robert C.]

Re: Don't confuse Black Phosphate w/ Black Oxcide *NM*

[Gerard F.]

Eastwood and Caswell

The Eastwood Black Oxide doesn't work on zinc plated parts, only bare steel or iron. I have the Caswell Zinc Blackener which I don't think it works very good. You have to have the part freshly plated with zinc, and I have gotten very spotty results on bolts and small carburetor parts (like the vent rod).

There must be better system out there where you can just clean up the zinc plating and dip in a solution. What do the platers do?

Jerry Fuccillo
#42179

[Gerard F.]

Just Read Chuck's Article on the CD

I guess there's no easier way.

Jerry Fuccillo