Quote:
Originally Posted by 28RPU
Question: A few years back I got some plastic dash board items for a 67 Ford "rechromed" as they were chrome before. The company in Texas that did it (beautiful,by the way) told me they put the plastic in a vacuum chamber and pipe in powered aluminum dust to simulate chrome plating. Was he doing it a different way back then or are they many methods of doing it? I dont see how you can "plate" plastic since it can't attract the metallic particles.
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Vacuum metallization is a process for applying via vapor deposition a thin layer of aluminum to a plastic. It is typically used for automotive lamp reflectors, even in cheap plastic flashlights.
Its main feature is its very high reflectivity, approaching silver, but it is very fragile and is also sensitive to environmental and chemical vapor exposure. It works reasonably well in sealed (tyvek vented) automotive headlamps, and is currently how most reflectors are finished for the last 20 years.
Chrome plated plastics are done as I described earlier. The plastic is first etched to create a porous surface to bond to, and it is treated with a tin/paladium catalyst to make it electrically active for the copper plating strike.
It is triple chrome plated, essentially the same as a metal part like zinc or steel.
If it is truly chrome plated, the primary reason the chrome peels is due to failure of the interface between the plastic and the copper. This is usually related to improper etching of the plastic resulting in the "wrong" porosity size and density of the etched surface.
Also, plated plastic is also sensitive to differential thermal expansion rates between the plastic and metal finish. They expand and contract at different rates during temperature changes, and this exerts additional stress on the bond interface.