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T O P I C R E V I E W
Posted - 02/19/2006 : 19:47:27Here's a list of various platings/coatings used on the beloved Mopars:
1. Phosphate- inexpensive coating in various shades of gray to black. This is a hot solution dip process that provides a moderate level of protection. Often seen on bolts, nuts & washers.
2. Parkerizing- appearance similar to phosphate, but it is a cold dip process and gives poor long-term corrosion protection. This is what the Eastwood blackening kit is. NOT USED ON ORIGINAL MOPARS!
2. Black Oxide- similar to phosphate, but somewhat more "charcoal-like" in appearance.
3. Clear Zinc- often called silver zinc...this is a base of zinc followed with a clear chromate dip. The chromate dip gives the bluish hue and varies depending on the particular dip. A straight zinc without chromate looks very close in appearance to cadmium.
4. Black Zinc- this is a zinc plating blackened by a chromate process. Can vary in appearance from brown to a rich black color and usually has a rainbow effect as well. Black zinc plating will degrade to an appearance that closely resembles gray phosphate. Careful inspection is required!
5. Zinc Dichromate- sometimes called yellow zinc.. This is straight zinc plating followed by a dichromate dip that creates the red, green, golden colors.
6. Red zinc- a couple fasteners used this color of zinc plating.
7. Galvanizing- this is a plating characterized by a leaf-like appearance. Seen on parts such as headlight cups, side marker brackets, etc.
8. Lead-Tin- a soft thick coating used on fuel filler tubes, etc.
9. Cadmium- used VERY little on post 66 cars. Has excellent corrosion resistance. Has a somewhat duller & grayer appearance than zinc plating. (Testing by dipping the part in a muratic acid solution can be used to determine if it's zinc or cadmium... zinc will fizz like an Alka Seltzer tablet.)
The appearance of the plating is directly affected by the metal's amount of polish and/or texture. This is why you should never sandblast parts before sending them in for plating.