Chrome Plating Basics

Taking a shine to chrome plating

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Almost every restoration project requires re-plating various parts. Cars and trucks built from the 1950s to the 1970s featured bright, flashy chrome plating on interior and exterior trim, giving these vehicles their distinctive character. But with age, metal finishes get chipped, pitted and scraped until they must be re-plated to look like new. This process can present some special problems, especially when re-plated parts need to visually match older plated parts on the vehicle.

Chrome Plating

A re-plated chrome part that may not match surrounding components is due to a change in the way parts are chromed. Originally, chrome plating was done with a hexavalent process, which produced great looking chrome but was later found to be toxic to the workers who did the plating. It also introduced deadly chemicals into the environment. A new chrome-plating procedure called trivalent plating was invented to reduce these dangers.

Trivalent is not as tough as hexavalent, but it is less susceptible to discoloration from heat. The biggest problem is that it usually has a darker and slightly brownish tint compared to the lighter, bluish tint of hexavalent. Unless you have two parts side by side, it is almost impossible to see any difference. However, if you are only planning on re-chroming only some of the body trim on an older car, the new parts will not be a visual match to the older pieces.

Hexavalent plating is gradually being eliminated around the world, so it is getting harder to find shops that will do it. A few specialty platers still offer hexavalent plating, but it's getting expensive. If you are re-plating all the trim on a vehicle, then using Trivalent for everything is a more affordable option.

The Process

The chrome-plating procedure is fairly simple. First, parts are cleaned and, if needed, bead-blasted. Old plating can be removed by dipping in a caustic acid solution, or with a "reverse plating" procedure. Once the part is squeaky clean, it is buffed on a wheel with progressively finer buffing compound until the base metal is perfectly smooth. If the base metal is pitted it must be welded up or ground down until smooth. Chrome does not act as a filler material and even tiny pits or scratches will be visible through the new plating job. If you can do the buffing and repair work yourself, you will save money at the platers. Much like a paint shop, the cost of materials is small compared to the labor involved.