Introduction
I've been hunting for my old computers in the loft. I've found 3 Amigas, 2 Commodore C128s, a Dragon 32 and an Atari 800XL. Some of the computer plastics have yellowed with time. Apparently it is UV (sunlight) that causes the discolouration, though my computers have been boxed neatly in the loft and not seen the light of day for over 20 years.
The computer and the two drives are supposed to have the same colour schemes in the above photo. The computer has gone somewhat yellow.
Investigations
It was quickly suggested that I try Retr0brite. This does exactly as its name suggests: makes retro things brighter. Thing is, it's more a formula than a product, you can't buy it as such. You can search for it on youtube, and one of the first videos I found explained what we're trying to do, and a ready-made product that can do the same job, available from chemists and hair salons. Thanks to "The 8-Bit Guy" for posting that. Links tend to change or disappear, so it's best to use your search engine to find retr0brite on youtube. Note the zero in retr0brite.
So What Are We Trying To Do?
The objective then is to apply a solution of hydrogen peroxide to the computer plastic that has discoloured. It then needs to spend a fair number of hours in UV light, so we need to stop the hydrogen peroxide from evaporating. Now as the videos explain, you would need a lot of hydrogen peroxide solution to soak a complete computer case, but you only need a little bottle if the hydrogen peroxide is mixed with a cream, such as in hair lightener.
At my local chemist I sheepishly asked for some hydrogen peroxide based cream, whilst trying not to make it sound like I was building something dangerous. Indeed, hydrogen peroxide was used as a fuel in the 2nd World War to power German U-Boats and the jet fighter ME 163, albeit in rather more concentrated form.
The strongest they had was some 30 volume Bblonde Maximum Cream Peroxide, which is actually 9% peroxide. In the video I watched, made in America, they used 40 volume (about 12%), they like to live dangerously. I bought the 75ml bottle, costing £1.69, about 2 Euros or just over 2 US dollars. Prices as at September 2017.
Bear in mind that this stuff is a bleach and can therefore burn. Wear plastic gloves and eye-goggles for safety. Some people spread the peroxide with their gloved hands, I chose to use a paintbrush.
The Process
Firstly we need to isolate the plastic parts that we want to improve. We shouldn't just apply the product to the whole computer as the product could get into the electronics or mechanical parts, it's pretty gooey, and we'll be wanting to clean it all off at the end.
Using my Atari 800XL as an example, the upper case is the only part I'm intending to clean. There are 6 screws on the underside that are holding the top in place. I removed those. The keyboard is also screwed to the top part of the case by 4 screws, with a ribbon cable running to the main board. There's also an earth wire connected to one of the 4 screws. I removed the 4 screws holding the keyboard in place, each of which has a locking washer on it.
This nicely freed up the upper part of the case. There are further tiny screws holding the dark brown smooth plastic that surrounds the keyboard, but I chose not to disassemble it any further.
I tipped a little of the hydrogen peroxide cream onto the top, and spread it evenly with a quarter inch (remember inches?) paintbrush. I just wanted to lightly cover the top surface of the light brown plastic. I also note that the bottle is dark plastic so as to prevent UV light from reacting with the hydrogen peroxide until you're ready. Next I wrapped the top surface with cling-film to stop the cream from evaporating, and placed the case on a wooden chair in the sunlight in my conservatory. If it had been a nice calm summer day I'd have put the case outside, bit it was fiercely windy.
Some people have what is called a "black light", a UV fluorescent tube or standard bulb, great for parties but otherwise largely pointless. I don't have one of those, but the sun does a fine job, even if it's occasionally cloudy. I suppose a tanning bed would work, albeit a rather expensive way of doing the job, but you would likely get results quicker.
The next part is to wait. I actually did this process 3 times over 3 days, leaving the case out for a total of about 15 hours. This really depends upon how much discolouration there has been. I don't believe that over-doing it will lighten the plastic beyond its original colour, it only seems to bleach the discolouration.
Each evening I removed and discarded the cling-film. I then wiped away the remaining hydrogen peroxide cream with a paper towel, and carefully rinsed the case with water, taking care not to get water under the darker plastic surround. I could then see the progress that was being made. The next morning I would renew the cream and wrap the case in cling-film for another sun session.
After 2 days I could see just a little discolouration to one end of the case so I went for a last session. By now I have used about half of my 75ml bottle., but then I've done 3 applications where maybe I could have just used the one.
The Keys
Now I didn't try this, and therefore don't know whether it's possible on the Atari 800XL, so I take no responsibility if you try. I have seen this sort of procedure done with PC keyboards, which are, on desktops at least, easily replaceable. If you do try it, take a photo of the keys in place first, or write them all down.
I did hear of a situation where a schoolteacher took all the keys off the school BBC Micro B and put them back in alphabetical order as an "improvement". One of the lads in the class did tell him that wouldn't work, but did he listen?
You can clean discoloured keys by carefully prising them off the switches, giving them a good wipe to get rid of the usual gunk that accumulates, before coating the keys in the hydrogen peroxide solution, and then either put them in a sealable plastic bag or wrap them collectively in cling-film. Then give them a good sun-bathe or time under the black light.
And finally...
Reassemble all the parts. That's 4 screws for the keyboard, with their locking washers, with the earth cable connected to one of them. I did notice that my Atari 800XL still had the original protective plastic on the name plate and the cartridge doors. I'll take that off and spray a touch of my WD40 Silicon Special Edition onto the metal cartridge doors to keep any moisture off them and make them all super-slick.
Lastly the case top is re-attached to the computer with its 6 screws.
The case looks all the one colour now, there is no yellowing that I can see: colour-blindness is a blessing in that respect! Compare this with the top picture in this blog showing the yellow discolouration.
The disk drive and tape drive are made of the same material but don't appear to have discoloured. This surprises me as I would likely have had to use all 3 devices at the same time, and in the same places. Anyway, I'm grateful because I don't fancy taking the tape deck or the disk drive to pieces.
Here's the product I used, other hair-colour modification products are available. I am suitably impressed, and may try it on an Amiga 1200 next. Apparently this procedure works on consoles, trainer soles, and action figures too.
Do go check on youtube for other retr0brite videos to see the process in more detail, and please be careful with hydrogen peroxide, especially if you follow any videos that direct you to make up your own cream mix. It does bleach hair, and such kits always come with plastic gloves to protect your hands. For good reason.
Thanks retr0brite!
Post Script
I also applied the cream to the Atari 1010 tape deck as that was looking a bit yellow on top and that cleaned up nicely with 2 day sessions in the conservatory with just the one application.
On the downside, the bristles on my paintbrush that I used have now got blonde highlights!
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