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.