Inspired by the 'Back from the dead ,Unyellowing Plastics (Retrobright)' posted by SOTZA. I have to agree the results are amazing, I have used peroxide creme (12%) mixed with a small amount of oxy stain remove. Any areas that may be damaged by the solution i.e. labels, printed lettering and chrome plated areas etc, must be masked with waterproof tape don't use masking tape. Here are a couple of examples: Sanyo M7750K My very nice Panasonic RX-5600 spoilt by a discoloured back: This is my first proper post on the new forum and it was so easy to do, which is great news. But I've just realised this is in the Walkman section! Now moved to Boombox tech section easily.
I used the regular hydrogen peroxide and the one concentrated 12% on a unit and was not able to clean the yellowish discoloration. One of my Sony PS-F5 turned to yellowish color and once i compare it with the other one the discoloration is obvious. I got a cheap mini boombox from eBay to try hydrogen peroxide on it before applying it to PS-F5 but I was not able to clean the yellow color. Any Idea ?
Here's what I use to make the whitening solution: Anything similar should work, I use the small red lid which holds about 75 ml and stir in half a teaspoon of the OXI powder (this is granules I crush it into a powder), this was enough to treat the back of the RX-5600, one application was enough it took about 45 minutes in bright sunlight to work. Sunlight is the key the reaction will only happen with plenty of UV light, you could use a UV lamp indoors but I haven't tried this. I apply it with a suitably sized brush, it will destroy most brushes after several uses. My advice is to experiment on some scrap or unwanted items before trying it anything in your collection. I have done a lot of tests on various types of plastic, it works best on the types of plastic boombox backs are made from, it is only really suitable for white or grey. I have tried it on different colours of plastic that have yellowed i.e. blue that has turned greenish and pink that has turned orange, while it did remove some of the discolouration it also bleached out some the original colour and often left streaks. Also it wasn't very successful on high gloss plastics, this might be because some of them although not painted as such may of had a clear top coat protecting the plastic beneath. This will also not work on most clear plastic, it may well help reduce some cloudiness but can only work on the surface, and clear plastic will in most cases be discoloured all the way through. A warning the solution is quite corrosive and will cause skin irritation, you should wear rubber gloves and some kind of eye protection, it will also remove plastic chrome plating, decals and damage aluminium, so anything like this that can't be removed mask it well with waterproof tape. Once you think you have the required result wash the plastic carefully with warm soapy water. I have also found that the solution is only good for a maximum of 2 hours after you have mixed the OXI in once it starts to become watery it's effectiveness is greatly reduced. Hope this helps anyone interested in trying this.
Wow, very interesting, I may try this on a fewer of my lessers and see how it comes out. Thanks for the tip.
WOW amazing. Panasonics and Sanyos seem to have this issue. Is it due to exposure to the sun? Or an unstable plastic mix? Or just the effects of time?
Yeah the results are good, it's probably a combination of all 3, but sunlight would be the major factor. From what I have read online the fire retardant used in the plastic becomes unstable after pro-longed exposure to UV light and becomes unstable and releases a brownish pigment hence the yellowing, the treatment stabilises the additive and removes the yellowing. The same thing will happen again if the treated plastic is left for long periods in sunlight.
