Plating and finishes: what a judge is actually looking at

The most common fault in an otherwise excellent restoration is over-finishing. Parts get plated, polished and painted to a standard the factory never applied, and the result looks like a show car rather than a correct one. If the vehicle will never be judged, none of this matters and shiny is a legitimate choice. If it will be, the finish on a bracket is worth as many points as the paint on the hood.

01The finishes you will meet

Zinc plating, usually with a chromate conversion coating over it. The most common fastener and bracket finish. It comes in several appearances:

• Clear or blue-white zinc — bright, slightly bluish. Common on interior and underhood hardware.
• Yellow zinc dichromate — the familiar gold-iridescent finish, often with a slight rainbow. Very common on suspension, brake and underhood fasteners.
• Olive drab — a dull green-brown, used on some heavier-duty and military-derived applications.

Getting yellow versus clear right on a given bolt is exactly the kind of detail that separates a well-researched restoration from a thorough one. Phosphate, most often manganese phosphate — a dull dark grey to black, slightly rough. Used on parts where a lubricant-retaining, non-reflective surface was wanted: many engine fasteners, some brackets, springs and clips. It is not black paint and it is not black oxide, and it does not look like either up close. Cadmium was widely used historically and produces a distinctive soft, slightly waxy silver — sometimes with a gold or olive chromate. It is genuinely what many original parts wore. It is also seriously toxic, and cadmium plating is heavily restricted for good reason: it is a known carcinogen and the plating process involves cyanide. Very few platers still offer it, and for a road vehicle there is no good argument for it. Modern zinc-based alternatives are made specifically to reproduce the appearance. Use those. If you are stripping original cadmium-plated parts yourself, that is a real exposure hazard — do not sand or bead-blast it dry, and do not do it in an enclosed space. Black oxide — a thin conversion coating, dark and slightly translucent, offering minimal corrosion protection on its own and usually oiled. Used on some fasteners and springs. Natural cast iron on exhaust manifolds, blocks and heads where nothing was applied. It rusts, and on a correct restoration that surface rust is *correct*. Painting an exhaust manifold silver is a very common and very visible error. Paint on engine blocks, brackets and inner panels — usually a specific colour per manufacturer and per year, and often applied with the part already assembled, so overspray onto fasteners and hoses is original. Masking everything perfectly is itself an inaccuracy.

02What judges actually look at

• Fastener head markings. Grade markings, manufacturer marks and the specific style of head. Correct-marking bolt kits exist for exactly this reason. A modern hardware-store bolt with the wrong markings is immediately visible to anyone who knows.
• The right finish on the right part. Yellow zinc where yellow zinc belongs, phosphate where phosphate belongs.
• Casting numbers and date codes, and whether they are plausible for the vehicle's build date. A part cast after the vehicle was built is a problem.
• Overspray and factory sloppiness. Real assembly lines left inspection marks in grease pencil, paint dabs on fasteners to show torque had been checked, and overspray in the wheel wells. Removing all of that is removing evidence of originality.
• Whether it is over-restored. An engine bay finished to a standard no factory ever achieved reads as wrong to an experienced judge, however impressive it looks in a photograph.

03Practical approach

Photograph and bag everything as you disassemble. Note which finish each fastener had before you strip it. Once a bin of bolts is mixed, the information is gone and you are guessing. Keep original hardware where you can. Re-plating originals preserves the correct head markings, which is worth more than new hardware in the correct finish. Use a plater who understands restoration work. Ask specifically for the finish you want by name. A general plating shop will give you bright zinc on everything because that is what industry orders. Do not blast everything. Aggressive blasting rounds edges, removes casting numbers, and changes surface texture permanently. Match the media to the part, and stay away from date codes and stampings. Research your specific vehicle. Finishes changed by year, by plant and sometimes mid-year. General rules are a starting point, not an answer. Marque clubs and judging manuals for your specific vehicle are the real source, and they exist for most of what is on this site.

04And the honest caveat

Most vehicles are not judged and never will be. If yours is a driver, there is nothing wrong with yellow zinc on everything, a painted manifold and stainless fasteners throughout. It will look good and it will last better than correct. What is worth avoiding is spending correct-restoration money and effort and then losing it on details that were knowable — because the finish on a hundred fasteners is not something you can go back and change once the vehicle is assembled.