Nut & bolt finishes for '70

[Steve G.]

I am about to start the process of putting my car chassis back together following a disassembly, cleaning, painting... I am trying to make it 'NCRS correct'.

I have read numerous posts on finishes of hardware, but I am still not clear on it. From what I've read, I believe I should get a black phosphate kit for hood latches and a grey phosphate kit for toe kicks.

Here is where I get a bit confused. I've read most of the other nuts and bolts on the frame are black phosphate or black oxide. Did I get that correct? If so, is there a source that says which hardware is black phosphate, which is black oxide and which is plated with other finishes? Someone mentioned using Caswell Plating for kits. I found a black oxide finishing kit on their website. Do they or someone else make a black and grey phosphate kit? Steve

[Joe L.]

Re: Nut & bolt finishes for '70

I am about to start the process of putting my car chassis back together following a disassembly, cleaning, painting... I am trying to make it 'NCRS correct'.

I have read numerous posts on finishes of hardware, but I am still not clear on it. From what I've read, I believe I should get a black phosphate kit for hood latches and a grey phosphate kit for toe kicks.

Here is where I get a bit confused. I've read most of the other nuts and bolts on the frame are black phosphate or black oxide. Did I get that correct? If so, is there a source that says which hardware is black phosphate, which is black oxide and which is plated with other finishes? Someone mentioned using Caswell Plating for kits. I found a black oxide finishing kit on their website. Do they or someone else make a black and grey phosphate kit? Steve

Steve------

Black oxide was rarely used for Corvette fasteners. Black phosphate, on the other hand, was widely used. The coloration of a black phosphate-finished part varied from black to gray.

[Terry M.]

Re: Nut & bolt finishes for '70

The best indicator of the original finish of the fasteners on your car is the fasteners themselves. As you remove them from the car record their size, head mark, and finish. Often one can find remnants of the original finish under the head or on the unexposed shank of the fastener. If you just pulled the car apart and threw the fasteners in a bucket, you just threw away your best evidence.

[Alan S.]

Re: Nut & bolt finishes for '70

Hi Steve,
Yes, materials are available to enable you to do the phosphate finishes at home. It's relatively easy to do with good results. Try Google for 'Palmetto Enterprises'. I have both the zinc and manganese; the zinc gives a dark gray finish, while the manganese is almost black.
Back in 1991, in THE RESTORER Vol.18 No.2, Robert Farrell had a very useful article and extensive charts detailing the finishes he found on his 66 chassis, components, and hardware. Although the info is based on a 66, I found MANY of the same finishes on my 71 as I took it apart. He lists more than a hundred items. If you don't have access to th article let me know and I'll send it to you.
Regards,
Alan

[Randy R.]

Re: Nut & bolt finishes for '70

One source is shooterssolutions.com

[Steve G.]

Re: Nut & bolt finishes for '70

Thanks Alan, yes please do send me the article. That would be much appreciated. I did check out Palmetto Enterprises website. But I am still confused. They imply phosphating and parkerizing are the same thing. Caswell plating (http://www.caswellplating.com/kits/index.html) implies black oxiding and parkerizing are the same thing (see description for black oxide kit). It seems like there is an endless loop here.

Joe, you mentioned black oxide was rarely used. Do you know if it was used at all for '70? And if so, where?

I do have all the bolts and hardware labled and in bags. I can't really tell the difference between black oxide and phosphate. The only ones I can tell apart are the few that have a metailic looking (zinc?) plating on them. Although I can see the coloring difference between my hood latches (black) and the backsides of the toe-kicks (gray). I believe the front sides must have been 'blacked out' as they are definately not gray.

Steve

[Joe L.]

Re: Nut & bolt finishes for '70

Thanks Alan, yes please do send me the article. That would be much appreciated. I did check out Palmetto Enterprises website. But I am still confused. They imply phosphating and parkerizing are the same thing. Caswell plating (http://www.caswellplating.com/kits/index.html) implies black oxiding and parkerizing are the same thing (see description for black oxide kit). It seems like there is an endless loop here.

Joe, you mentioned black oxide was rarely used. Do you know if it was used at all for '70? And if so, where?

I do have all the bolts and hardware labled and in bags. I can't really tell the difference between black oxide and phosphate. The only ones I can tell apart are the few that have a metailic looking (zinc?) plating on them. Although I can see the coloring difference between my hood latches (black) and the backsides of the toe-kicks (gray). I believe the front sides must have been 'blacked out' as they are definately not gray.

Steve

Steve-----


Black oxide produces a smooth, non "chalk-board-like" finish. If you've ever seen an ARP fastener, this is an example of a black oxide finish.

The only fasteners I can think of on a 1970 that I believe were black oxide finished are the front steering arm-to-knuckle bolts. No others come to mind.

To give you an idea of how uncommon that black oxide finish is among GM fasteners, of the bolts, SAE and metric, available from GM in SERVICE over the last 20 years, or so, a total of ZERO have been black oxide finished.

[Patrick H.]

Re: Nut & bolt finishes for '70

Thanks Alan, yes please do send me the article. That would be much appreciated. I did check out Palmetto Enterprises website. But I am still confused. They imply phosphating and parkerizing are the same thing. Caswell plating (http://www.caswellplating.com/kits/index.html) implies black oxiding and parkerizing are the same thing (see description for black oxide kit). It seems like there is an endless loop here.

Joe, you mentioned black oxide was rarely used. Do you know if it was used at all for '70? And if so, where?

I do have all the bolts and hardware labled and in bags. I can't really tell the difference between black oxide and phosphate. The only ones I can tell apart are the few that have a metailic looking (zinc?) plating on them. Although I can see the coloring difference between my hood latches (black) and the backsides of the toe-kicks (gray). I believe the front sides must have been 'blacked out' as they are definately not gray.

Steve

Palmetto is correct.

Phosphating and parkerizing are the same process.
Black oxide is entirely different.

Here's the cheap, easy answer: don't worry about black oxide. Purchase a quality black phosphate kit from Shooters solutions, Palmetto Enterprises, Caswell or similar. Then, go have fun plating your own bolts.

Patrick

[Terry M.]

Re: Nut & bolt finishes for '70

Parkerizing used to be (and may still be) the brand name of a phosphating process sold by the Parker Chemical Company. I used iut 45 years ago in the job I had at that time.

The AIR injection tubes are black oxide finish.

[Steve G.]

Re: Nut & bolt finishes for '70

Thanks all.

I was on the phone with Scott from Palmetto Enterprise earlier this evening. He recommended bead blasting the hardware just before cooking in their solution. I don't have a bead blaster at home, but do have access at a body shop. Am concerned if I bead blast the bolts, bring them home and wait a couple days before using the solution, I may have rust issues. Has anyone compared bead blasting vs one of the rust remover chemical dips? If so, do both methods work equally well? If so, I may try the dipping method. Steve

[Michael G.]

Re: Nut & bolt finishes for '70

Joe,

Black oxide was most commonly used over stainless steel on exterior trim fasteners. It was also used on the stainless interior fasteners of some cars that were available in converible models. Visually, its sometimes tough to tell this finish from the multi-layer black used on non-stainless screws for such applications.

I guess its possible to service all these parts with the non-stainless multi-layer finish, but I'd be very surprised if some service fasteners for such applications were not stainless with black oxide.

Mike

[Grant W.]

Re: Nut & bolt finishes for '70

Thanks all.

I was on the phone with Scott from Palmetto Enterprise earlier this evening. He recommended bead blasting the hardware just before cooking in their solution. I don't have a bead blaster at home, but do have access at a body shop. Am concerned if I bead blast the bolts, bring them home and wait a couple days before using the solution, I may have rust issues. Has anyone compared bead blasting vs one of the rust remover chemical dips? If so, do both methods work equally well? If so, I may try the dipping method. Steve

Hi Steve
It is best to have all the equipment before you go into the home plating method.
Bead blaster, electric wire wheel like the 1/2 horse one with the grinding stone on one side. Crock pot, or stainless steel pot, Long style 4 inch deep stainless steel pan, Long enough for the splash pan under the passenger and drivers side.
If the parts have any hint of rust you have to bead blast it again. If you plate and don't like it then you can bead blast. I've zinc phosphated many parts as trial and error. Getting the right temp etc etc. When I screw up or don't like the finish I blast it and start all over.
Rust chemical remover helps on the very rusted parts but you must later blast it. Blasting it puts a fine even finish so when the plating or boiling of the item, it will coat and give the even look finish.
I can go on and on but if you like just email me.
Thanks, Grant

[Alan S.]

Re: Nut & bolt finishes for '70

Hi Steve,
I'm still too un-tec to attach anything to my NCRS E-mails. If you'll send me your E-mail address I'll send you the 'THE RESTORER' pages.
I found that the phosphate finishes were the easiest to do successfully at home of all the plating. I don't have a blast cabinet but used a wire wheel on a electric motor and then a metal cleaning solution. If I had been wiser in the beginning I would have gotten a blast cabinet... maybe next time.
I'll send the info off right away.
Regards,
Alan

[Joe L.]

Re: Nut & bolt finishes for '70

Parkerizing used to be (and may still be) the brand name of a phosphating process sold by the Parker Chemical Company. I used iut 45 years ago in the job I had at that time.

The AIR injection tubes are black oxide finish.

Terry------


If I am recalling correctly, I don't think the AIR tubes were actually black oxide. It definitely appears a lot like black oxide, but I think it's a finish referred to as "black zinc". I'm not 100% sure, though.

[Terry M.]

Re: Nut & bolt finishes for '70

And I have never seen a print of those, so I could be wrong as well. I was simply trying to offer something most would be familiar with as an illustration of the difference between black oxide and dark phosphate.