What is this finish?

A. Hi Piotr. In the picture it looks to me to be blue with white speckles. Is there any reason to think it's other than paint? Is it actually silver colored rather than blue-white and the picture is deceiving?

Trying to guess what such a finish is from just a photo cn be difficult, but if you can tell the readers what the component actually is, it's possible that people familiar with such products will know what the common finishes are. Thanks.

Luck & Regards,

A. I have been in the fastener business for 26 years, there is only one way to tell the difference in plating types, and color is not one of them. You should look for a local metal finisher in your area. These parts might be i.d. by them, but an acid test is the best way. Different platers have different results in colors of plating, plus how clean their tanks and chemicals are at time of such application ... Good luck!

A. Hello John. Although Rick is surely right, your specific problem with the alternator pulley is probably not to "identify the finish" but to recognize the 'semantics' and phrasing involved in the situation.

Cadmium plating always receives chromate conversion coating as a post treatment. Whether the color of that coating is yellow vs. gold is arguable in every instance; some people would call a chromate yellow that you might call gold and vice-versa. The color difference can be quite subtle, and it can be accidental or deliberate.

On the next point, yes, although there is a chemical difference between chromate (Cr03) and dichromate (Cr2O4), the coating is called a chromate conversion coating regardless of the exact percentage of chromate and dichromate in the coating.

So, a 'gold cad' is cadmium plating followed by a chromate conversion coating which is, to the eye of the beholder, gold in color. A 'yellow cad' is cadmium plating that has received a chromate conversion coating that is, to the eye of the beholder, yellow in color. A yellow dichromate is actually an oxymoron since dichromates are orange, but again it's a chromate conversion coating that is yellow to the eye of the beholder. Identifying the chromate finish without identifying the plated metal would be incomplete though. A 'yellow dichromate' may well mean cadmium plating with yellow chromate, but it could also mean zinc plating with a yellow chromate.

So it's not a matter of deciding which of the three coatings you have based on a color chart; it's a matter of deciding what to call a finish which consists of cadmium plating followed by a chromate conversion coating of a yellowish or goldish tone -- I'd call it cadmium plating with yellow chromate. Good luck.

A. The initial surface will determine the finish of the plating job; the fact that it is a matte finish just means that the metal underneath had a matte finish when it was plated.

In addition, any plating method (with few exceptions) for use on tools usually involves hazardous chemicals that are difficult and costly to dispose of, and equipment that a hobbyist doesn't have access to.

If you want a clear answer take it to a professional plater and have them figure it out.

A. I think you will find that the originals were polished and anodized. The pre anodizing must have included an etch step (hence the semi-bright finish) and a fluoride desmut step which removed much of the silicon at the surface so that the anodized coating is essentially colorless. The anodizing may also have been done to a less than customary thickness to preserve color.

If the surface now conducts electricity, then there is no coating, anodized or organic. It has been removed sometime in the past. Either that or you are probing through the surface coating. To properly test for coating conductivity, use an ohmmeter with light pressure.

None of the above applies to newly manufactured replacement parts. They could be anything.

A. I tend to agree with Jeff. They were anodized aluminum. After all these years it may be difficult to get a nice job of anodizing again simply because the castings are old and any debris in the castings may have broken down and oxidized. Consequently there are pockets of onon-aluminum which will not readily accept the anodizing and leaves blemishes.
I think your best bet is to have them polished to a nice bright finish and keep them cleaned and waxed on a regular basis.
Or try getting them painted in a nice bright gray finish that looks close to what they looked like new. Most people will not notice the difference as long as it is well done and all the colors are consistent.
Or course if nothing will do but the original anodized finish then start looking for a reputable place that does custom anodizing and listen very closely to what they say. Too often a customer will have such a desire for a perfect result that they will fail to listen to the possible problems that may occur. Then everybody is unhappy. Of course for the right amount of money anything is just about possible. But estimating a job like that could be off by many hundreds if not thousands of dollars.
Go for the nice matching paint and take the money you save for another project or improvement on your current project.
But hey ! It is only my two bits of opinion.
Of course a real nice chrome job might look good too. Just make sure you find a reputable place. Go to their before and after gallery and make sure they are up to it. Good Luck

A. Hi Julian. You got two terrific responses. The only thing I'll add as a point of general information is that aircraft stripper will remove virtually any organic coating (paint, lacquer. clear coat) but will have little or no effect on inorganic materials (castings, platings. etc.). Other readers should know, though, that it is horribly toxic stuff and only for professionals with proper PPE and training.

Luck & Regards,

A. Hi Joseph. Just from appearance, odds are about 99+% that it's a sacrificial plating of cadmium, zinc, or zinc alloy with a yellow chromate finish.

But whether it's cadmium (which is a bio-accumulative toxin that should be reserved only for very special needs) and whether the chromate is hexavalent (which would be a RoHS problem) can't be determined visually or with normal warehouse stuff. Some plating shops could do spot tests to determine what it is if it's a large enough bag to be worth it. (Are you sure those bolts are new? There is a ring just below the head that looks either much less worn or much more worn than the rest of the shoulder). Good luck.

Regards,

Ted,

Thanks! I appreciate your help.

Hi Alex. I'm reluctant to guess what the substrate or plating is, but a university in your area will probably have an X-ray fluorescence machine which can answer your questions without polishing or destructive testing. Good luck.

It's interesting that the logo on the Captain's badge is more abstract. Someone knowledgeable in artistic styling trends may be able to say which logo is older based on art trends.

Regards,

A. The badges are most likely Nickel Silver, an alloy of copper, nickel and zinc which contains no actual silver.

The center emblem of the first piece likely had a thin gold plate over plate.

A. Hello Andy, looks like cast iron with a natural black finish which was done primarily with oil. With the level of rust you described, it is very unlikely that the key was plated or had a corrosion protective finish. I also noticed that the ridged part of the key is duller, possibly from wear over time disengaging the tumbler. To keep the authenticity of the key itself, I would try to hand finish with repeated oil rubs, which will help seal the pores of the iron.

A. Hello Andy, boiled linseed oil is a choice of many people.

A. Re. the Ford logo. I don't recognize this as anything which was done at the Ford factory.

It looks like the work of a later owner/hobbyist - possibly aluminum pigmented "silver" paint.

A. Hi Damian. From just looking at the photograph it looks like gray/silver colored paint on a white styrofoam or plastic ball. But if you tell us what the part is, what it does, and a theory of what scratched it, better guesses are probably possible. Thanks.

Luck & Regards,

A. Hi Mark. I can't get a sense of scale or material of construction. Can you tell us what is is, how big it is, what it seems to be made of, and whether you saw it inside a building vs. out in the elements? If it's outside and showing no rust, I'd guess it's black oxided stainless steel.

Luck & Regards,