With all of the parts removed from the coin door, I thought it would be wise to give them a thorough cleaning before reassembly. The coin acceptors on this machine are gray plastic and looked somewhat brown-ish. Because hands touch this area when inserting a coin, I figured it was simply accumulated grime I could scrub off. Scrubbing them in soapy water did remove some of it, but there was still a distinctive brown hue left on the plastic. This reminded me of something I read about recently…

If you’ve ever seen beige or gray plastic age over a number of years, it does sometimes develop a brownish hue. Some chemistry geniuses at the English Amiga Board figured out this is caused by a breakdown of atomic bonds in the plastic. Bromine is added to plastic during the manufacturing process to act as a flame retardant and it eventually finds its way to the surface. UV light tends to accelerate the process. I’m no chemist, so that’s the best explanation I can provide. You can read the real theory behind it here. I found it fascinating.

The same geniuses who figured out what was causing this problem also figured out how to reverse the process without damaging the part. Simply coat the part in a solution they developed and expose it to UV light for a number of hours. I’d never tried it before, but I’ve been curious to see how well it would work. The solution itself is easy to make and the developers have given out the recipe for free on their wiki.

I mixed up a small cup of the solution and dropped in one of the coin acceptors. I then put it under a black light to provide some UV exposure per the instructions. Here are the treated and untreated coin acceptors side-by-side after 12 hours: (I adjusted the contrast and brightness to make the difference stand out more)

Front side

Back side

So, Retr0Bright does work. Awesome. 🙂