The Golden Ticket: Zinc-Cadmium Restoration
Pop the hood on any muscle car and you will see a lot of different coatings. One that always grabs your eye is the golden Zinc-Cadmium plating. This brightly-colored plating is designed to protect the substrate metal from oxidation by acting as the sacrificial anode that gives itself up in order to save the base metal. The OEMs used several versions of Zinc and Cadmium plating, depending on the use of the part.
Zinc Plating—This type of plating was widely used on 1967 and later Mopars, as well as some others, due to Zinc being more durable. Zinc plating comes in several colors: Zinc Dichromate (the classic iridescent yellow\gold), Black Zinc, and Clear Zinc (silver colored). Zinc tends to have more shine and requires less maintenance than Cadmium plating. Zinc plating is currently done at several plating shops across the country.
Cadmium Plating—This is what you find under the hood of most muscle cars. Cadmium plating is duller than Zinc plating. The classic yellow-gold color is iridescent with green and red highlights. True Cadmium plating is very dangerous because several highly-toxic chemicals are involved, and is considered to be a severe environmental hazard. Cadmium plating is mostly reserved for aviation equipment today. Just like Zinc, there are different colors of Cadmium plating, the most common being Gold or Yellow Cadmium, but also clear, olive green, and black.
Cadmium and Zinc plating was commonly used on hardware such as bolts, brackets, vacuum boosters, reservoirs and valves, and lids (master cylinder, etc), and even door hinges. Determining whether you have Yellow Dichromate-Zinc or Cadmium plating is not easy, the main difference between the two is the shine. Unless you are having the part re-plated, it really does not matter, since they look almost identical. Since re-plating is expensive and not always possible, recreating that look is a great option. To that end, we ordered up The Eastwood Company’s Golden Cad painting kit.
The kit comes with four aerosol cans; Gold base, Red highlight, Green highlight, and Diamond Clear. The process is quite simple. We set our sights on a vacuum power booster from a GM A-body. We practiced on a few scrap pieces to get the hang of it before moving on to the actual part. The key to the process is the red and green highlights. The overall color is gold, but the iridescent nature leads to faint patches of red and green. Applying this in a random fashion is critical to a proper job. Having a plated piece on hand for a reference is a good idea. On our reference pieces, the red and green highlights tended to be more pronounced over bends and valleys, such as the ribs in a lid.
1. This booster came off a Buick GS. It is pretty crusty and in need of some TLC. It functions perfectly, so why replace it? The new booster to the side is for reference.
2. The booster was disassembled from the master cylinder. We also removed the vacuum port and grommet.
3. The first step is cleaning. The booster had some early rust scale formation, which we removed with a scotch-brite pad. This is your basic medium to fine grit kitchen scrubber.
4. Then we blasted the booster with some Eastwood PRE prep spray. This stuff is great for removing oil, residue, and even brake fluid from the metal.
5. The booster was wiped clean and ready for paint. Notice at the bottom right of the booster there is some residual Cadmium plating. It really is good stuff.
6. We set up a makeshift paint booth using a cardboard box. This process generates a lot of overspray, so this is a good idea.
7. First, we laid on the base coat of Golden Cad. If the metal was heavily pitted, we would have primed and sanded it smooth, but this booster was in good shape.
8. You are looking for a nice even finish over the entire part. The paint is a little slow to come out of the can, so start spraying elsewhere or you will end up with some junk on the part.
9. Next, the red highlights. There is a trick to this. You only want to add some highlights, not spray the entire part. For a part like this, the peaks and valleys are a good place to start. Keep it random.
10. Like this. Note on the lower left how the red runs across the rib in a stripe? Whoops. No worries, a little touch up with the gold base will soften that up.
11. Now the green highlights. Same story, different color. The green is used even less than the red, as the green is more subtle.
12. Green tends to show up more in the flat areas, so that is where we concentrated.
13. Don’t forget to do the back side!
14. Before moving on to the final step, you can spray on a mist of gold base to soften the highlights. This works really well.
15. The final step is the Diamond Clear. We laid it on nice and even, allowed it to dry and put on another coat.
16. All done! We assembled the booster with the refinished master cylinder (and Golden Cad plated lid).
Sources:
Eastwood
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