Plating for Bolts, nuts, brackets during frame restore

[Bill L.]

Re: Plating for Bolts, nuts, brackets during frame restore

I have been phosphating at home and found that a product call RPM Rust Prevention Magic works very well for keeping the plating from rusting. It smells a bit like shoe polish/wax. You use a small paint brush and a hairdryer to melt the RPM on the hardware.

I am very pleased with the results. I Like the fact that it is not oily.

I have used Richard Fortier for plating and he did some clear zinc and phosphate before I started doing it at home.. His work is first class.

Bill

[Patrick H.]

Re: Plating for Bolts, nuts, brackets during frame restore

This finish is put on by dipping in a solution for about 30 seconds. No power supplies are required. It is a water based solution. I put the parts in a webbed oinion bag and dip and swirl. Once out of the solution, the part need to be dried with a paper towel immediately, then the sealer from Caswell put on immediately. I think the sealer displaces any remaining water and adds oil. WD40 seems to work as well.
After an hour, I paper towel this then let it sit overnight, then add satin clear.

Black oxide is different, it was tiny crystals that shine in the light. This finish is much harder to do at home since it involves some nasty chemistry and requires high crock pot heat. I don't know how well it is for corrosion. But I suspect it is better than black phosphate.

Black phosphate is going to rust whether it is sent out to be plated professionally or done at home. It's just a matter of when. It is so much easier to keep track of parts at home, less hassle and probably a lot cheaper. Using a plater, you will probably save all the parts for everything, body, engine, powertrain bumpers. Then send it out as a batch- not tagged. This makes me shudder.

Steve,

I'm going to suggest that you have some of your finishes misidentified. Black (or manganese) phosphate, also known as Parkerizing, is applied using heat and involves placing the part in 180-190 degree solution for several minutes. It results in a dark gray-to-black finish which may appear to have tiny crystals depending on the light. It is very easy to do at home, and I've been doing it for years. My latest method is to use an old Coleman stove outside in the driveway, and I check the temp of solution using an IR gun. It works well and my home applied finishes look great years later.

I do not know what kit or method you have been using, but I would suggest that what you've been applying at home is not black phosphate.

Patrick

[Jeffrey S.]

Re: Plating for Bolts, nuts, brackets during frame restore

Just to expand on Patrick's comments- unless they have introduced a new product that I am unaware of, the Caswell kit is black oxide. It is done at room temperature or, depending on the age of the solution or type of steel, at 110 degrees. It yields a smooth, dark black finish. I have been using it for years and have never had a part rust. Of course the parts are not subject to salt or rain, etc. Black (or grey) phosphate is done, as Patrick said, at around 200 degrees and yields a light to dark grey speckled finish. This is more consistent with factory type finishes. I don't think the black oxide finish was ever used in production. Today it is used on fasteners that come with aftermarket assemblies like TV pull-out/slides, etc.
Jeff

[Bill C.]

Re: Plating for Bolts, nuts, brackets during frame restore

from what I recall -

black oxide is a cold process and is most likely to wear off and rust.

The phosphates are all heat process - they generally hold up very well over time.

I parkerized my heat shields and male/female hood lock parts - more than 5 years ago - and they look new now.

If you need to get the parkerizing solution - give Grant Wong an email. He has a bottled product that works 100% -
you can get his contact information from the NCRS membership list.

[Michael G.]

Re: Plating for Bolts, nuts, brackets during frame restore

Some of the above comments are not quite correct, so I thought I'd add some info:

There were several finishes on the '72 era Corvette. All of them, except cadmium, offered extremely minimal corrosion protection. If your car has normal exposure to the elements and has not been restored, you can expect that all of the fasteners are now significantly corroded. You probably can't identify most of them by current color as they're going to be red rust, except perhaps some rare cadmium parts, which might still have some shiny silver, mixed with grey and red-brown corrosion.

The chassis and engine finishes used were, in order of most usage: 1) zinc phosphate and oil dip (medium grey to black, rough crystalline surface), 2) zinc plating with chromate dip (smooth silver plated appearance, with various hues of transparent chromate from clear to yellow), 3) zinc phosphate with black paint dip, them oil dip (dark grey to black rough, with varying degrees of oiliness). 4) cadmium with chromate dip (smooth whitish-silver plating, sometimes with a yellow tint form the chromate). There were some other but they were very rare.

Interior parts might have zinc-phospaphate coated parts without the oil coat (grey, rough crystalline) or very, very rarely black oxide (black with small crystalline surface).

All of these are still available from platers, but all of these will easily corrode if you expose your car to rain or humidity. There are alternatives with much superior corrosion performance also available. I'd recommend, that if your going to bother to re-plate fasteners, you use a current plating or you'll be re-doing them soon.

[Peter S.]

Re: Plating for Bolts, nuts, brackets during frame restore

I agree with Bob, you will find most, if not all, of the chassis finishes in this book. Joseph also detailed the head markings on each of the chassis bolts.

[Patrick H.]

Re: Plating for Bolts, nuts, brackets during frame restore

Some of the above comments are not quite correct, so I thought I'd add some info:

There were several finishes on the '72 era Corvette. All of them, except cadmium, offered extremely minimal corrosion protection. If your car has normal exposure to the elements and has not been restored, you can expect that all of the fasteners are now significantly corroded. You probably can't identify most of them by current color as they're going to be red rust, except perhaps some rare cadmium parts, which might still have some shiny silver, mixed with grey and red-brown corrosion.

The chassis and engine finishes used were, in order of most usage: 1) zinc phosphate and oil dip (medium grey to black, rough crystalline surface), 2) zinc plating with chromate dip (smooth silver plated appearance, with various hues of transparent chromate from clear to yellow), 3) zinc phosphate with black paint dip, them oil dip (dark grey to black rough, with varying degrees of oiliness). 4) cadmium with chromate dip (smooth whitish-silver plating, sometimes with a yellow tint form the chromate). There were some other but they were very rare.

Interior parts might have zinc-phospaphate coated parts without the oil coat (grey, rough crystalline) or very, very rarely black oxide (black with small crystalline surface).

All of these are still available from platers, but all of these will easily corrode if you expose your car to rain or humidity. There are alternatives with much superior corrosion performance also available. I'd recommend, that if your going to bother to re-plate fasteners, you use a current plating or you'll be re-doing them soon.

Michael,

I'm going to state that I have been able to replicate factory colors most accurately using black (manganese) phosphate. I find that zinc phosphate is generally lighter in color than original pieces I own which still have original finish on them.
There may be a couple of part that tend to be lighter in color, but I do not find that to be common.
I'm not sure what parts on a 70-72 would have zinc phosphate and then black paint dip and then an oil dip. For one thing, the oil wouldn't add much and wouldn't really stick to the paint.

Your opinion may vary.

Patrick

[Michael G.]

Re: Plating for Bolts, nuts, brackets during frame restore

Patrick

For what its worth, my opinion is that of a former GM fastener engineer and long time member of the GM fastener finish committee. I am very, very very familiar with each finish used by Chevrolet in that era, including all of those I described, and have tested each, and many more, extensively.

Manganese was really not commonly utilized in GM fastener coatings.

Zinc phosphate, with paint dip and oil was one of the most highly utilized GM finishes throughout the 70s and 80s. The phosphate absorbed paint for corrosion protection, the oil lent additional protection by sealing the paint and adding lubricity. That finish lent corrosion protection at least double that of phosphate and oil alone.

[Frank T.]

Re: Plating for Bolts, nuts, brackets during frame restore

I just top flighted my friends 72 on Friday with a score of 97.4 first time out. I can help you with your questions on your finishes. Just give me a call after 4pm eastern. 321 848 5249. Frank Jr.

[Patrick H.]

Re: Plating for Bolts, nuts, brackets during frame restore

Patrick

For what its worth, my opinion is that of a former GM fastener engineer and long time member of the GM fastener finish committee. I am very, very very familiar with each finish used by Chevrolet in that era, including all of those I described, and have tested each, and many more, extensively.

Manganese was really not commonly utilized in GM fastener coatings.

Zinc phosphate, with paint dip and oil was one of the most highly utilized GM finishes throughout the 70s and 80s. The phosphate absorbed paint for corrosion protection, the oil lent additional protection by sealing the paint and adding lubricity. That finish lent corrosion protection at least double that of phosphate and oil alone.

As noted, my comments were based on duplicating the finishes I see with the products that we mere mortals can purchase.

I'd be interested in an example of a plated/painted/oiled part if you know of one off hand.

Patrick

[Roger D.]

Re: Plating for Bolts, nuts, brackets during frame restore

Some of the above comments are not quite correct, so I thought I'd add some info:

There were several finishes on the '72 era Corvette. All of them, except cadmium, offered extremely minimal corrosion protection. If your car has normal exposure to the elements and has not been restored, you can expect that all of the fasteners are now significantly corroded. You probably can't identify most of them by current color as they're going to be red rust, except perhaps some rare cadmium parts, which might still have some shiny silver, mixed with grey and red-brown corrosion.

The chassis and engine finishes used were, in order of most usage: 1) zinc phosphate and oil dip (medium grey to black, rough crystalline surface), 2) zinc plating with chromate dip (smooth silver plated appearance, with various hues of transparent chromate from clear to yellow), 3) zinc phosphate with black paint dip, them oil dip (dark grey to black rough, with varying degrees of oiliness). 4) cadmium with chromate dip (smooth whitish-silver plating, sometimes with a yellow tint form the chromate). There were some other but they were very rare.

Interior parts might have zinc-phospaphate coated parts without the oil coat (grey, rough crystalline) or very, very rarely black oxide (black with small crystalline surface).

All of these are still available from platers, but all of these will easily corrode if you expose your car to rain or humidity. There are alternatives with much superior corrosion performance also available. I'd recommend, that if your going to bother to re-plate fasteners, you use a current plating or you'll be re-doing them soon.

Michael, can you elaborate on what alternative finishes are available and the correlated finish that they would replace? Also, would these alternatives be acceptable to future judging?

Roger

[Roger D.]

Re: Plating for Bolts, nuts, brackets during frame restore

I just top flighted my friends 72 on Friday with a score of 97.4 first time out. I can help you with your questions on your finishes. Just give me a call after 4pm eastern. 321 848 5249. Frank Jr.

Frank, thanks for that kind offer. I need to first read and then re-read through this thread a couple of times to get my head around it. Before I do that, I'll probably need to check out the Chassis Restoration Guide that Bob suggested (I believe I have one handy close by). Once I feel like I understand the basics here I will give you a call, perhaps sometime this week.

Thanks to everyone else who has weighed in on this topic so far.

Regards,
Roger

[Terry M.]

[Michael G.]

Re: Plating for Bolts, nuts, brackets during frame restore

Terry. In fastener manufacturing, the lubricants applied to steel wire to aid drawing and forming are removed after forming, prior to application of the final coating or plating. The coatings you find on finished parts are usually put there to enhance corrosion protection. In the 70's and 80's, almost all finishes (except perhaps cadmium) were allowed to be very inconsistent in friction due to the lack of specified torque/ tension relationships on GM prints or specs. For example, platers were allowed to choose any oil they felt like for phos and oil, so long as the minimum corrosion requirements were met.

Patrick, there were many hundreds of GM parts with phos and oil and hundreds more with phos-organic (phos, paint, and oil) coatings. One thing you should know is that both the oil and paint were usually applied by separate "dip-spin" processing, in which centrifuges spun off the excess paint and/or oil, so such parts often looked a lot like black-colored phosphate with the oil not very evident. Certainly, fifty years later it would not be visible. Unfortunately, while I used to have a lot of these part numbers memorized, its been a long, long time and I have no access to GM info on those parts. I have many new samples of those finishes at my office though, so if you're ever in Wixom, let me know and we'll look at some.

[Patrick H.]

Re: Plating for Bolts, nuts, brackets during frame restore

Patrick, there were many hundreds of GM parts with phos and oil and hundreds more with phos-organic (phos, paint, and oil) coatings. One thing you should know is that both the oil and paint were usually applied by separate "dip-spin" processing, in which centrifuges spun off the excess paint and/or oil, so such parts often looked a lot like black-colored phosphate with the oil not very evident. Certainly, fifty years later it would not be visible. Unfortunately, while I used to have a lot of these part numbers memorized, its been a long, long time and I have no access to GM info on those parts. I have many new samples of those finishes at my office though, so if you're ever in Wixom, let me know and we'll look at some.

Michael,

How about doing a presentation for our Chapter on finishes? That way the info could be given to more members than just one.
I'd bet I could get you on the agenda for the October annual business meeting if you wish, else plenty of opportunities this winter.

Patrick