Black Phosphate Preservation

[Jimmy G.]

I just got a lot of black phosphate bolts and stuff back from the plater today. I remember someone stating that some sort of rust inhibitor would add longivity to my bolts. Any thoughts??

[Bill W.]

Re: Black Phosphate Preservation

Hi Jimmy . On cars that wont see rain etc. I use motor oil . Let them soak then remove excess with a rag . On things that will be in weather or you dont want to rust ever use Cosmoline weathershed . you can spray or dip it . let it soak then wipe off it leaves a wax coating. It works great on raw cast iron to .

[John D.]

Re: Black Phosphate Preservation

Jimmy, Try Eastwood Diamond Clear satin finish. John

[Mark S.]

Re: Black Phosphate Preservation

Adding to John's comment; there are many other brands that offer a clear satin finish that would also work. Mark

[Peter S.]

Re: Black Phosphate Preservation

Hey Jimmy,

I've hopped on the Boeshield T9 train. I cannot speak to its longevity since the bolts I have coated have not seen driving conditions yet.

http://www.amazon.com/Boeshield-T-9-.../dp/B001447PEK

[Edward J.]

Re: Black Phosphate Preservation

Jim, I will put in my two cents, I did the home remedy black phosphate 8 years ago on my 72's Chassis and bumper hardware,(not driven in the rain) I just pickled the bolts with oil and in this time I have only recoated them once. NO RUST IN THIS TIME.

[Michael G.]

Re: Black Phosphate Preservation

Phosphate itself does not offer any corrosion protection. It is intended only to be applied to a metal surface as a substrate that would absorb liquid oils and paints that do offer protection.

You can paint over dry phosphate with a clear paint and get some protection, or you can dip the fastener in an anti-corrosive oil such as "FrogLube" to get something that performs very well and looks like the original.

[Fred Y.]

Re: Black Phosphate Preservation

Like the men mentioned here Jimmy the Phosphate offers no corrosion protection. I too use the Diamond clear that John mentioned. It keeps the bolts with the flat finish. Just DON'T read the VOC's on it--LOL---"good stuff" I get mine from Eastwood/Yellow & White can.

[Alan S.]

Re: Black Phosphate Preservation

Hi,
Caswell includes a 'preservative' as part of their black oxide 'kit'.
It's an oil of some sort. I use it with manganese phosphate too.
After dipping the restored part it's quite shiny but as it dries it looses most of it's shine.
I like it because when dry it doesn't attract any contaminants.
I also still use Prelube6 too.
Regards,
Alan

[Gene M.]

Re: Black Phosphate Preservation

Wipe them down good with STP if you are driving the car. Good long term protection but a little oily and hard to hold on to when finger starting the bolts.

[Michael G.]

Re: Black Phosphate Preservation

The thing to remember here is that the "phosphates" that GM used were really phosphate coated and then oil dipped (through the mid-seventies) or phosphate coat, black paint dip, plus oil (later). The phos and oil usually didn't appear oily, because the oil was absorbed, but it could, if it were at the bottom of the shipping box. Its color varied all over the spectrum from grey to black There was no particular "specified" oil, so platers put lots of different oils on, so long as they could meet the minimal corrosion requirements GM had then. I heard that some used waste oil, but since I was on GM's finish committee, nobody actually claimed that sin to me. Neither of these finishes really added much corrosion protection, though, even with a good oil. If they got out of the plant without corroding, all was good.

With something like FrogLube, or three or four other products, you'll easily beat the original specifications and it'll still look like the factory finish.

Gene, I wouldn't use STP on important stuff, its way too slippery, much more slippery than the original finish, you're likely to break or yield some bolts...

[Gary B.]

Re: Black Phosphate Preservation

...
With something like FrogLube, or three or four other products, you'll easily beat the original specifications and it'll still look like the factory finish.
...

All,

Specifically which FrogLube product are people talking about? It looks like FrogLube makes a handful of different products; paste, liquid, & solvent.

Gary

[Michael G.]

Re: Black Phosphate Preservation

Gary, I used a liquid, available in gun shops, I believe, but I can't give specifics on the particular product right now, I'm in Florida on vacation and my garage is in Michigan... I'll PM you next week when I get back...

[Gene M.]

Re: Black Phosphate Preservation

A good substitution for black phosphate finish that is far better corrosion protection is black zinc chromate. As it ages the appearance will better replicate black phosphate. My thought is if base clear urethane paint is ok in substitution of lacquer than why not black zinc chromate for black phosphate?

Availability of black zinc chromate at most plating shops is more prominent than black phosphate.

[Michael G.]

Re: Black Phosphate Preservation

Gene, black chromated zinc appears much different than phosphate finishes. Its shiny, a bit iridescent and doesn't have the rough surface texture of phosphate. It's corrosion performance is also highly dependent on plating thickness. Most platers save time and money by putting too little zinc on, because the purchaser (you) can't tell how thick it is. As such, the corrosion performance is usually not what you expect. That's why all of the repro fasteners I've bought corrode quickly and often: the zinc is too thin.

Additionally, black zinc's first corrosion products are white, so even slight zinc corrosion stands out on your car. As with all zinc coatings, its friction coefficient is also much higher than phosphate and oil, so using it as a replacement for phosphate reduces the clamp-load in your attachments - not good.