Correct fasteners and finding the "real" thing

[Mike R.]

in the judging guide there are statements like "known original (FI) cars have XX headmark bolts with black oxide plating. There are various posts here stating that aluminium manifold cars have zinc plated intake manifold bolts. Does the statement in the JG mean that mean that the black oxide bolts were used on *at least some* cars but that other cars may have different bolts?

Second question: I have bought some reproduction bolts to replace hardware store bolts previously installed and the reproduction bolts have a shiny finish whereas that original bolts have more of a matte finish. I assume that the original bolts are plated with cadnium and the reprodution bolts are plated with zinc(???) I often find myself needing one or two bolts and I want it to match my original bolts. Is there a supplier who has bolts with the original configuration?

On a related note, what is the best way to clean bolts without damaging the plating? Some have sealant and paint on them. I would put them in my oven on the self cleaning cycle but my house has smoke detectore in every room!

[Gene M.]

Re: Correct fasteners and finding the "real" thing

The reproduction bolts are plated with zinc, many also have a clear chromate treatment. This makes them shine and pretty.... If you give them enough time the shine will degrade and look as the others do. And the correct finish is zinc, some did have chromate while others did not. The duller finish is general accepted as no chromate.

Bead blast your originals and send them out for plating. Repos are not exact creation of originals. Most judges can't tell the difference.

[Michael G.]

Re: Correct fasteners and finding the "real" thing

There are two "silver" platings that were commonly used on mid-year fasteners: zinc plating with clear chromate, and cadmium plating, also with clear chromate. If properly done, these platings appearances are all but indistinguishable from each other, they both are shiny silver, their respective hue each widely variable due to slight coloring of the "clear" chromate

Original manifold bolts used were plated with the zinc and clear chromate. Common repos of these parts are also zinc and clear, the difference being that the the plating thinkness on the repos is usually much thinner than the original zinc. This means that they corrode faster.

As zinc corrodes, it tends to form initial corrosion products that are white and powdery. Later, the corrosion becomes red, as the base metal rusts. The white corrosion makes the shiny silver appear dull, as you are seeing on your older bolts. If you think a bolt was plated with cadmium, it is a very poor idea to clean it yourself, by any method. Get a new bolt, cadmium is very, very bad stuff.

Note that some cadmium plating is not "shiny", normally due to the absence of chromate, but there are other causes.

While "bead-blasting" works for cleaning fasteners before re-plating, it is better to clean them with a brass wire wheel. (be careful and wear safety goggles) This removes less steel and leaves no dimples in the surface. Your plater will pickle (acid dip) the parts before plating anyway, but you should get the paint and rust off beforehand.

[Ronald L.]

Re: Correct fasteners and finding the "real" thing

Mike,

I beg to differ on the cad versus zinc. As long as I have my eyes I'll be able to tell the difference. CAD plate has a softer Yellow look, zinc bright and to the blue side. Once you get a little time on them, water & heat, etc, the difference is even more pronounced.

Touching them is OK, just as long as you don't go biting your nails, ingestion is the issue...and HExavalent Chromium is the worse, ...FWIW.

[Scott S.]

Re: Correct fasteners and finding the "real" thing

Mike,

I beg to differ on the cad versus zinc. As long as I have my eyes I'll be able to tell the difference. CAD plate has a softer Yellow look, zinc bright and to the blue side. Once you get a little time on them, water & heat, etc, the difference is even more pronounced.

Touching them is OK, just as long as you don't go biting your nails, ingestion is the issue...and HExavalent Chromium is the worse, ...FWIW.

Hi Ron,

My research from a while back indicated that Hexavalent chrome was the type used in the 1960s and results in a slightly different (bluish?) hue than non-hexavalent chrome. Most places don't do hexavalent chrome these days for EPA reasons, but some do, it just costs them more to stay in compliance with regulations.

Is it correct that hexavalent chrome is correct for items like bumpers on midyears? What about interior chrome fasteners?

Is there any reason to be concerned about handling/cleaning/polishing hexavalent chrome (either fasteners or bumpers, for example)?

[Chuck S.]

Re: Correct fasteners and finding the "real" thing

...Second question: I have bought some reproduction bolts to replace hardware store bolts previously installed and the reproduction bolts have a shiny finish whereas that original bolts have more of a matte finish. I assume that the original bolts are plated with cadnium and the reprodution bolts are plated with zinc(???) I often find myself needing one or two bolts and I want it to match my original bolts. Is there a supplier who has bolts with the original configuration?

On a related note, what is the best way to clean bolts without damaging the plating? Some have sealant and paint on them...

The shine of plated parts has little to do with the type of plating, and everything to do with the smoothness of the surface being plated. This was true on the original parts and it's true on the reproductions. Present day manufacturing methods virtually insure that every modern zinc plated fastener is very smooth and very shiny.

Typical zinc electroplate is very thin, maybe several tens of thousandths of an inch thickness. The thin electroplated layer therefore follows the terrain of the part surface very closely.

Consequently, if a part has a rough surface finish going into the plating baths, it's going to have a bright, but rough surface coming out, unless your intent is to fill imperfections. Large industrial bearing journals may spend 24-48 hours being chrome plated in order to rebuild and restore them to standard size. The residence time in the typical zinc electroplating bath is just long enough to provide a good rust resistant coating...probably a few minutes.

If you want a matte finish on your fasteners, beadblast them before plating. A smooth reproduction fastener can be made matte by stripping the fastener in dilute muriatic acid, bead blasting, and replating. It's a big pain, but it's the only authentic way I know to do it.

Cleaning paint and sealants off fasteners is probably best done by simply washing them in lacquer thinner, which will eventually dissolve most organic contaminants. Once black phosphate fasteners are clean, I would reapply oil to darken them and keep any bare spots from rusting.

[Scott S.]

Re: Correct fasteners and finding the "real" thing

If you think a bolt was plated with cadmium, it is a very poor idea to clean it yourself, by any method. Get a new bolt, cadmium is very, very bad stuff.

Hi Michael,

I have no idea which fasteners are cadmium and which are zinc, I have hundreds of labeled bags of fasteners and most are corroded (43-year old Ohio car, originally from Philadelphia). The entire car is disassembled and I have been cleaning and handling all of the fasteners in preparation for re-plating.

For removing rust, I have been using a liquid solution called "Evapo-Rust", which seems to do a very good job removing rust from chrome fasteners without damaging the chrome (leave them submerged for a day or two). Works okay on other surfaces, unless the rust is deep.

The "Evapo-Rust" is non-toxic, and gets all over my hands (along with whatever it has dissolved, probably including cadmium) regularly. Since the Evapo-Rust is non-toxic, I have been using it indoors. It sounds like if some of the fasteners I've been working with were cadmium plated (some probably are), I may have created a dangerous situation, both to myself and the house. If someone could explain what kind of danger I may have been exposed to, and what to do about it, I would appreciate it.

While "bead-blasting" works for cleaning fasteners before re-plating, it is better to clean them with a brass wire wheel. (be careful and wear safety goggles) This removes less steel and leaves no dimples in the surface. Your plater will pickle (acid dip) the parts before plating anyway, but you should get the paint and rust off beforehand.

The "Evapo-Rust" works better on some fasteners than others, I wasn't too concerned about it since all the (non-chrome) fasteners will be acid-dipped by the plater prior to re-plating anyway, until I read your comments about cleaning them thoroughly before acid-dipping. Won't the acid-dip take care of any paint and rust, or are there other reasons to use a brass wire-wheel on everything before re-plating?

This is my first time doing most of these things, and I don't know what I don't know. I research what I can, and the rest is by trial and error.

Thanks,
Scott

[Ronald L.]

Re: Correct fasteners and finding the "real" thing

Chromium, in the proper form actually is a very important mineral and the lack thereof is <in the human diet> linked to sugar metabolism problems, but that is another topic.

Back to cars, the plating on bumpers and most interior part is the pure metal Chromium. As long as you're not as acid as cola, you will have no problem polishing, kissing or even cooking in chromium containing pots & pans, stainless steel has two forms, iron plus chromium, and iron, nickel and chromium.

THe build up of a bumper is a follows, copper, then nickel which gives the hardness and majority of corrosion protection (is yellowish and not shiny) and then chrome, blueish and bright, shiny.

Acids remove chromium and then you have hexavalent chromium - which is VERY toxic! The concentrated solutions we used to plate bumpers were of this ionic form. The waste waters we would treat to convert it to a trivalent form which was significantly less toxic.

As far as fasteners are concerned, the interior screws are chrome plated and low risk, usually you can get them replated or buy new, depending.

The zinc dichromate is a zinc plate with a proprietary coating containing a chromate. It is not soluable in water, so toxicity is not an issue unless you are acid striping and or somehow ingesting these coatings.

Cadmium fits about the same bill, it has superior corrosion resistance to zinc, and yes, it is toxic too, like hex chrome.

If you are blasting these parts, the glass bead, aluminum oxide, or other media has just as many warning regarding injestion and you should be using a good respirator. If you do that, send the parts out and have a professional shop do the replate, you are all set. One way to beat the minimum charges is to pool your orders, the minimum is usually 10 pounds of metal, clean ready to plate.

If you use the home plating systems people have discussed here, you need to then follow the safety precautions included with those kits. Any and all of these metals will mess you up if you are careless.

hope that helps

[Chuck S.]

Re: Correct fasteners and finding the &quot;real&quot; thing

...It sounds like if some of the fasteners I've been working with were cadmium plated (some probably are), I may have created a dangerous situation, both to myself and the house. If someone could explain what kind of danger I may have been exposed to, and what to do about it, I would appreciate it...

I think you can relax, Scott.

I'm skeptical that simply handling plated fasteners is going to create a health hazard. The EPA's problem with cadmium and hexavalent chrome (the new stuff is trivalent chrome, and yes hexavalent was original to most our cars) is the disposal of the waste byproducts of the plating operations. Before the EPA got involved, platers were probably just dumping heavy-metal-rich sludge from their plating tanks in a pond on their back lot with nothing to prevent ground water contamination.

Unless I'm way off base, plated metals will be analogous to asbestos...as long as you don't disturb the material, you are fine. I doubt that even wire brushing cad plated parts will generate enough free material to cause you problems, but as when spraying catalyzed paints, if you do it day in and day out as a career, it will likely kill you without proper protective gear.

[Scott S.]

Re: Correct fasteners and finding the &quot;real&quot; thing

Hi Ron,

It definitely helps, thank you for the reply.

Acids remove chromium and then you have hexavalent chromium - which is VERY toxic! The concentrated solutions we used to plate bumpers were of this ionic form. The waste waters we would treat to convert it to a trivalent form which was significantly less toxic.

My bumpers were replated with the Hexavalent chrome about two years ago, by a chrome-plater in Florida who still offers Hexavalent chrome. I understand that the process itself is toxic, but if I understand correctly, it sounds like once the bumpers are plated and finished, it is safe to handle them, clean them, etc.

As far as fasteners are concerned, the interior screws are chrome plated and low risk, usually you can get them replated or buy new, depending.

The interior screws are in good shape mostly, so I'm just cleaning them, and replacing incorrect interior screws that found their way onto the car over the years with correct original fasteners.

The zinc dichromate is a zinc plate with a proprietary coating containing a chromate. It is not soluable in water, so toxicity is not an issue unless you are acid striping and or somehow ingesting these coatings.

The only parts I can think of at the moment requiring zinc or cad dichromate are the '67 brake master cylinder cap and various carburetor parts (no power brake booster on this car).

Cadmium fits about the same bill, it has superior corrosion resistance to zinc, and yes, it is toxic too, like hex chrome.

I thought cadmium had better corrosion resistance, and since the JG usually specifies either zinc or cad, I would rather use cadmium for durability, as long as there is not a health-hazard problem. I won't be doing any plating myself, I will leave that to someone with experience in this area and the proper methods to address hydrogen embrittlement issues.

If you are blasting these parts, the glass bead, aluminum oxide, or other media has just as many warning regarding injestion and you should be using a good respirator.

I don't have a bead-blasting cabinet (yet), I do have a Craftsman bench grinder, so I was going to get a brass wire-wheel to use with it.

If you use the home plating systems people have discussed here, you need to then follow the safety precautions included with those kits. Any and all of these metals will mess you up if you are careless.

I will leave the actual plating to the experts. If everything else I have mentioned above sounds reasonably safe, then I won't worry about calling in a Haz-Mat team to detoxify myself or the house.

[Paul J.]

Re: Correct fasteners and finding the &quot;real&quot; thing

It sounds like if some of the fasteners I've been working with were cadmium plated (some probably are), I may have created a dangerous situation, both to myself and the house. If someone could explain what kind of danger I may have been exposed to, and what to do about it, I would appreciate it.

Scott

Scott, the concentrations aren't high enough for a long enough period of time. Don't sweat it.

The last paragraph of Chuck's post (#9) says it best.

Paul

[Michael G.]

Re: Correct fasteners and finding the &quot;real&quot; thing

Ron,

You don't have to beg, we'll just differ on this one. Maybe you can tell the difference, but I'm sure I can easily fool you (no offense intended).

After many years in fastener engineering and fifteen on GM's fastener finish committee, having run a fastener company, and seen literally millions of new zinc and cadmium plated parts, I'm pretty sure that if two identical fasteners were plated in 1966, one with cadmium and one with zinc, they would differ so little in appearance that 99.9% of the people looking could not tell them apart. Back when all GM lock nuts were cadmium, I tested thousands of them against zinc nuts, both had clear chromate and wax. If they got mixed, NOBODY I know could tell them apart. We later used yellow chromate on the zinc nuts. After a few months on a car, though, its easy to tell all of them apart them apart; the zinc corrodes.

With that said, a lot of cad I've seen plated recently is different in appearance than it was a few years ago. Its softer and more yellow than it used to be. I have no clue why. If anything, the cad was very slightly more whiteish than zinc in the old days.

Scott, Just don't glass bead cadmium parts, or use a wheel on them, because the dust is toxic. Cadmium is a bio-accumulative carcinogen. Unless you're drinking the "Evapo-rust" you're OK.

[Scott S.]

Re: Correct fasteners and finding the &quot;real&quot; thing

Chuck and Paul, thanks for the replies!

[Scott S.]

Re: Correct fasteners and finding the &quot;real&quot; thing

Scott, Just don't glass bead cadmium parts, or use a wheel on them, because the dust is toxic. Cadmium is a bio-accumulative carcinogen. Unless you're drinking the "Evapo-rust" you're OK.

I will do my best to keep from ingesting the Evapo-Rust

As for not media-blasting or using a wire wheel on cadmium parts, I can avoid doing that on the following parts, which I am aware of because I found them listed in Dobbins' book:

Accelerator rod and bracket
Bolts supporting spare tire well
1967 brake cylinder cover (gold)
Coil bracket, 396 & 427
Clutch cross shaft
Distributor vacuum advance
Door panel clips, 1965-67
Fuel block, 396
Hood latches, fire wall, spring black
Hood support
HP alternator pulleys
Male hood latches (spring black)
Radiator hose clamps
Thermostat cover, 1966-67
Valve cover bolts for aluminum covers


As for the fasteners (probably bolts mainly, but maybe screws too), how can I tell whether an old corroded bolt was originally zinc or cadmium, before blasting away or grinding on a wire-wheel?

Also, I am still unclear as to why it is even necessary or advisable to blast or wire-wheel them, if the fasteners will be acid-dipped before replating?

[Chuck S.]

Re: Correct fasteners and finding the &quot;real&quot; thing

0310 0480 0003 4238 0125
...Won't the acid-dip take care of any paint and rust, or are there other reasons to use a brass wire-wheel on everything before re-plating?...

The acid bath will not remove oil and grease, and it won't remove paint.

Generally, the plater's process will have a very hot, strong detergent (Oakite) bath to remove oil and grease before the acid bath, which is really only intended to remove minor surface rust that may form between fabrication and plating.

Your best bet is to have your fasteners and parts PERFECTLY CLEAN before you take them to the plater. Your plater is not going to clean the rust off your parts.

Acid cleaning is likely to provide the smoothest surface for plating. Wire brushing will also keep a smooth surface smooth, but be careful to avoid "brush marks" and sworls from the wheel. Bead blasting will yield a matte finish after plating, even if the original part was smooth.