Refinishing bolts

[Jim Baxter]

Ok I am ready to put the car back togather, but I have these bolts and washers that are rusted and some have paint on them, that I don't think are suppose to be painted. How do I clean them up, and how do I know if they were painted originally?

[Robert C.]

Re: Refinishing bolts

That's hard to tell without knowing where the bolts came from Whether they were painted, plated etc. There's lots of rust removers out there.

[Eugene B.]

Re: Refinishing bolts

Jim,
I'm sure that you will get lots of good advice from other members; here is the process that I use for my '65.

Degrease all items in parts washer. Wire brush nuts, bolts, washers, lock washers, etc. with bench mounted power wire brush. Chase all threads with taps and dies as required. Refinish.

The answer to your question about how do you know if the fasteners were originally painted. You will be able to get most of this information from the judging guide. Also by understanding what was bolted to what prior to engine painting, etc.

I do not replate fasteners because of the possibility of weakening them do to hydrogen embrittlement. For fasteners that are black phosphate, I use Joe L.'s recipe for oven-baked black phos.

Hope this info is helpful.

Good luck with you car,
Gene

[Roger Legge]

Re: Joe L. Black Phos Recipe, Please?

Could someone please post or email me the recipe for this oven baked black phosphate treatment? Thank you in advance.

Roger

[Chuck S.]

Re: Refinishing bolts

Your best shot at determining the original finish on fasteners is to examine the individual fasteners closely for any remnants of the original finish. This is best done during the disassembly process as they are cleaned, bagged and tagged. Success at this endeavor will depend on the amount of rust on the car before the restoration was begun. If you have a virgin no-rust car, it is fairly easy; if you have a rust-bucket, it will be impossible.

Fasteners that were originally black phosphate or natural are the ones most likely to be rusted beyond recognition. Black oxide is a tougher finish, but application is more selective in my experience. Black phosphate will have a fine crystallaline structure in the finish that reflects light; its somewhat like looking at your concrete driveway in bright sunlight. Black oxide is a slick, hard finish compared to black phosphate. Be careful not to identify worn black oxide as black phosphate; the black oxide may have have near-microscopic flecks of plating missing that makes it appear as black phosphate (it's happened to me). Zinc plated fasteners should show some sign of the original finish under the worst conditions in my opinion.

I would agree with the sequence given above for cleaning during disassembly. If fasteners are caked with grease and dirt, clean them with mineral spirits. Once you remove the protective grease, you may be able to determine the original finish. If they are completely covered with rust, then you are pretty much SOL on identifying the original finsish, but give them a good close examination before wire wheeling or bead blasting...you certainly won't able to make any determination afterward.

If all else fails, feel free to apply my arbitrary rules of thumb on fastener finish. These are BFG (BIG FAT GUESS) or ALR (ABSOLUTE LAST RESORT) categories; USE AT YOUR OWN RISK: For chassis fasteners, say 1/4" and larger, use black phosphate. Fasteners 3/16" and smaller could be either black oxide or black phosphate. Zinc is used on the chassis sparingly, but you should be able to see where. Natural fasteners are also used on the chassis in a few applications; you will almost have to know these from observing restored cars or reference books. In the engine compartment, excluding the engine, use black phosphate primarily but there small screws that may be black oxide. Any fasteners on the engine that are black, are typically black oxide in my experience.

[Chuck S.]

Painted Fasteners

To my knowledge, all factory painting was done before anything was assembled, so no fasteners (except some interior screws) should be painted. Use lacquer thinner to try and dissolve the paint without disturbing the finish (if any) underneath. Most likely the paint was applied to cover rust, but it's possible "detailing" overspray. Once the paint is off, follow the advice above.

[Eugene B.]

Roger - you have Email. *NM*

[Patrick H.]

Gene - would you mind posting it? Thanks. *NM*

[Jim Baxter]

Re: Gene - would you mind posting it? Thanks.

Thanks for the excellent response. The bolts in question for me are the ones holding the radiator support on top bottom and sides, the fan schroud, I am confused on the types of finishes, do you have any pictures to elaborate?

[Jim Baxter]

Re: Gene - would you mind posting it? Thanks.

Found this on the bolts

http://www.stanleyind.com/finfo/plating.html

[Eugene B.]

Simulated Black Phosphate Recipe

Gentlemen,
I have received several requests for Joe L.'s famous recipe for oven-baked black phoshate. Must be getting close to Thanksgiving.

I will state up-front that this is a simulated finish and may be seen by judges to be non-authentic; therefore, I accept no responsibilty for any points deducted.

Having said that, here is the information that Joe posted and I modified based upon discussions with Quanta:

1) Clean fasteners and prepare them for painting.
2) No primer is used.
3) Spray items with a thin coat of Quanta Black Oxide Spray P/N 0715.
4) Allow them to air dry for approximately 24 hours.
5) Place fasteners in an oven-proof metal pan and cover with aluminum foil.
6) Bake items in a pre-heated oven at 350 degrees F. for 30 minutes.
7) Turn off oven and allow items to return to room temperature.

A recipe that even us guys can follow. I'll acknowledge and thank Joe for passing it on to me and others.

For those who desire a more authentic finish, consult the catalogs of Eastwood and Caswell.

Best regards and good Corvetting to all.

Gene

[Chuck S.]

Clarification of Black Finishes

Jim, I can understand your confusion on the black finishes after rereading my previous post.

What I was trying to say with the driveway analogy is that the tiny crystals in the black phosphate reflect light individually as you turn or move the part relative to the light source...uh...kind of like the old mirrored rotating globes in ball rooms. Clean black oxide is a slick, smooth, uniform finish with a slight gloss by comparison; in my experience, black phosphate will never get too shiny even when oiled (unless oil is dripping off).

The best way to understand the appearance of phosphate finishes is to examine a known phosphate finished part IN BRIGHT SUNLIGHT...then you will understand. You cannot see this in a photograph. On shark cars, the hood latches are probably the easiest parts to see that are black/gray phosphate. The clamps retaining the heater hoses and AC hoses to the right inner fender are either black phosphate or painted (I forget which is which, but if they ain't painted, then they're black phosphate.) Black bumper bolts, body tapping plates, most all chassis fasteners, positive battery/starter cable retaining clamp at bellhousing, and about 180 other specific classes of parts and fasteners are phosphate finished on 70-72 Corvettes.

You never said which year class your car is, but for fasteners on the radiator support, the odds are 8 to 2 that the fasteners are black phosphate. Reproduction of authentic black phosphate finishes is covered in the archives, but is probably not worthwhile unless you doing the "perfect" body off restoration.

[Jim Baxter]

Re: Clarification of Black Finishes

No I am not doing a perfect body off, I am just trying to keep the car as close to original as possible. Its a 65 roadster. I am putting the radiator support, horns and schroud back togather tomorrow. I ordered the NCRS manual, Does anyone know if what kind of coating is on these bolts? Should, I paint them black or strip them off? It appears that they have something on the head of the bolt but I am not sure what it is, the previous owner sprayed black paint all over the engine compartment.

[Chuck S.]

Re: Clarification of Black Finishes

Jim, there are guys on this board that know the finish on those midyear fasteners off the top of their head. Repost the question, and specifically identify each fastener of interest.

[John H.]

Re: Clarification of Black Finishes

Virtually all of those fasteners were originally "phosphate and oil"; the only black oxide fasteners I recall on midyears are the cluster screws and the rivets at the ends of the dash in the door opening.