Yep, that’s it- Zinc chromate. I used it as a primer on forklifts. Odd yellow color. Not sure if you can even buy the stuff anymore. Probably faded away like good carb. cleaner that actually cleaned.
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ZnCrO4 (I am a chemist by trade, sorry Zinc Chromate :-)))) is still available, but mostly to the pros.
Anti-corrosion agent, a very good one at that. An absolute must for refinishing wheels and valve covers made of aluminum or magnesium alloys, but rarely done in practice.
Coating (be it paint or chrome) vs galvanizing - it is all a relative simple electrochemistry. As already discussed earlier in this thread, preparation of the substrate and quality is critical. Shamelessly lifted the following paragraphs off of a very good website finishing.com
“Sacrificial” vs. “Barrier Layer” Coatings and Why Quality is Crucial
First an aside: Some readers may be familiar with the replaceable zinc anodes used on ships and outboard motors to protect the hull or motor from corroding. What the zinc anodes do is sacrifice themselves to protect the steel. Zinc is “anodic” to steel, and what that means is that when the steel is under attack and about to lose electrons (which would cause the steel to oxidize and convert from solid metal to rust), electrons will flow from the zinc to the steel to maintain the balance and protect it, so the zinc corrodes instead of allowing the steel to corrode. Galvanized roofing materials are coated with zinc, and function the same way: the steel is pretty safe from corrosion as long as there is some zinc left on it to sacrifice itself.
Now, could you use a nickel anode or chrome anode instead of a zinc anode to protect a boat’s steel hull from corroding? Absolutely Not! Steel is “anodic” to the nickel, instead of the other way 'round. The current flows the wrong way. The steel will sacrifice itself to protect the nickel and chrome. So now imagine a steel item that is plated with nickel and chrome but there is porosity or pinholes in the nickel plating … the steel will rust away, sacrificing itself to try to protect the nickel! If you’ve seen a 50-year old junked rat-trap of a truck or car, you may have seen bumpers with thin pieces of curling nickel chrome, and almost no steel, where the bumper used to be.
Unlike “sacrificial” coatings like zinc plating or galvanizing where porosity or a hole or bare edge may be no big deal, porosity in nickel-chrome plating is a disaster that doesn’t merely fail to protect the steel, but greatly accelerates the corrosion of the steel. Chrome plating is a “barrier layer” plating; once the barrier is breached by a pinhole, very rapid rusting is unavoidable. A low quality chrome plating job with pinholes or porosity is much worse than no plating at all; the plating electrochemically forces the underlying steel to rust.
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I think it is, even regardless of the cost.
A good clean, wax, primer and of the shelf paint is more than adequate, plus scratches can be easily repaired, and there will be some for sure.
lots of useful information for the one in the same boat, ie how to restore the front crossmember
I was pondering taking it out to get it powder coated, not sure now this would be the best idea
I had a quick search for zinc chromate paints or primer, and those aren’t available here, at least for non professionnals
There are many reasons why this stuff is unobtanium. Here is just one.
You’ve seen the movie Erin Brockovic, right?
Chromate = hexavalent chromium = the stiff that made her a household name.
I don’t like to quote the wikipedia, but will make an exception here (generally good write up):
Yeah, listening to you guys, and talking with MY tech bud (he’s retired with like 12 valid trade licenses and a million tools), a simple sandblast, primer, paint and wax is sufficient. But I’ll probably let someone else prime for me, because too much time between sandblast and prime could result in some instant surface rust?
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I had seen the movie, and remembered the chrome part, but not the full formula / exact product involved
I was even surprised such primer was still available in the USA (
iirc only impossible to ship to 2 or states, )
I’ll try and find some less extreme primer, but will go paint instead of powder coating
Leaving the ‘A’ arms rusty?
You mean top wishbones? No, but I can do them later, I was first taking care of everything that depended on removing springs. Now waiting for some new bushes and I’ll do top wishbones then. Plus they’re more dirty than anything…
Do you have an idea how much does the crossmember weigh?
I was planning on doing wishbones with Sub-Frame. But are the wish bones also iron, or steel?
I “think” it’s about 35kg , but it depends if you weight the cross member alone, or the full front (hubs and disks, wishbones, …)
each bit isn’t that heavy, but all add up
I 've got a bare crossmember in the garage, I can weight it if someone want to know -it seems to be sound, so no rust lightening)
No official proof, but they seem like iron to me.
I doubt that it is pure iron, I think it would be too brittle, but they do have that look and feel. Likely a steel recipe of some kind.
On the calipers I used Zinc paint first, was unhappy with how it looked. Aluminum paint looks great (short of plating…) and stands the heat… did you paint the bleed screw too - I‘m sure you have new ones to install of course.
In any case the A arms don’t have a rust problem. The spring pan can rust though and you should have a good look. Maybe coat them.
Not so sure about that one . J>C> smith is a truck broker and mechanic in Ohio. I saw a pice by him on You tube as to powder coat on a semi’s fuel tanks and battery box. Very much ecposed to water, snow and worse, salt. Not good, horrible.
Paint is better!!!
Carl
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