Disclaimer: The following information documents my own use of 'Retrobrite'. Follow these instructions at your own risk. If you apply this stuff to your rare Commodore 65 and ruin it, don't say you weren't warned!
You may have noticed that light colour plastics on old micros can go orange. Is this dirt? No, it's down to exposure to UV light, sometimes decades ago. Can you reverse this? Well yes, with a technique called Retrobrite.
I'm not going to go into the science here, but rather document my own first experiments with it. Naturally I wouldn't want to risk anything valuable with such an experiment but I had a broken Amiga PSU case going spare. It had really bad yellowing (I guess the heat didn't help) so it seemed an ideal candidate.
The ChinnyVision Guide To Retrobrite In 10 Photos
First up you need to wash your plastic and remove any paper labels. The PSU was filthy and I had to get every last piece of dust and dirt off of it. I also had to remove the paper label. Washing in soap and water alone didn't get it off but a healthy dose of isopropyl alcohol did.
One clean Amiga PSU. Look at the bit on the left piece that had been covered for 22 years by a label. That's the original colour! Can we get it back to that colour in one afternoon?
This is what you'll need to Retrobrite an Amiga PSU.
1 Clean Paintbrush
2 Ziplock Freezer Bags
Rubber gloves and appropriate eye protection
Be Blonde 40% Hydrogen Peroxide Solution (available from Superdrug).
Something to work on. I'm using a padded envelope here as it has plastic inside so nothing can soak through.
I'm using Be Blonde which is a hair colouring product which is known to contain exactly the correct ingredients for Retrobrite. Be wary of using other products, they may have additives that could damage the plastic. Be Blonde also has a paste like consistency which makes it easy to paint onto the PSU. It contains 40% hydrogen peroxide which is the strength that has been proven to work best. Be sure to buy the right one as different strengths are available in the same container.
So here we go. Slap on the Retrobrite generously. You don't want it to dry out. Get it in every nook and cranny. Be careful though, it'll burn your skin and bleach anything in sight.
Ouch! I forgot to wear gloves. And people put this in their hair! Don't be an idiot like me, wear gloves! And make sure you wear old clothes as well. It will bleach anything it touches!
Both halves of the PSU are smothered in Retrobrite. The bags are sealed up and left in sunlight. You need to keep an eye on them and keep topping up the paste. The paste must NEVER dry out!
90 minutes later I am still topping up and turning the case every 15 minutes. I'm doing this on a late August day with occasional cloud cover in the UK. Adjust the procedure for your own climate. As I said before you need to keep a close eye on them to prevent drying out.
3 hours after I started I put the PSU case back in the sink and carefully dispose of the ziplock bags. I note my paint brush is now fully blonde! I throughly wash the Retrobrite off of the case making sure it is out of every last corner of it.
The original is on the left and the results 3 hours later are on the right. It's fair to say after just 3 hours the case isn't as good as new, but it has considerably lightened. Unfortunately despite my best efforts, part of the case did show some minor blooming which means the paste did dry out.
Not bad for a first go though. The case is now much closer to the original colour as seen on the label section. Another treatment and it will improve further.
My strong advice with Retrobrite is to not only be very careful but to experiment on spare bits of plastic first. I did this as an experiment and currently have no intention of treating any of my micros, but I did want to see if Retrobrite worked and if it could yield any results on something as orange as my broken Amiga PSU.
I did this experiment 8 months ago and the PSU case has neither changed colour since nor has it become brittle or cracked. So the change to the plastic seems fairly stable.
Try it for yourself at your own risk. Your results may vary.