Retrobright
But lets start at the basic points.
Old computer cases are made of ABS plastics which contain at that time bromine. The bromine is included as a fire retardant. This element reacts over the time of years with UV light and causes the yellowing.
Retrobrighting describes a method that gives the case its old color back. But beware: this method will not extract the bromine out of the case and it could be that the case will yellow again over the years.
There are several recipes around to produce a fluid that causes that deyellowing. All of them contain hydrogen peroxide. This is the ingredient which causes the effect. You can compare this to bleach your teeth or hair.
Some people found out that there is a liquid, which is 'ready to use'. It is creme developer which is used by hair stylists to bleach hair. There are several products on the market - I used 'Wella - Welloxon Perfect 12% 40 Vol.' but other products should be very similar.
If you want to start such a project please read until the end until you got the right understanding what to do and take your time. If you are in a hurry this project will fail.
Again: Take your time and always work save with gloves, safety goggles and old clothes. The used chemicals are unhealthy and will discolor clothes.
Be aware that the condition of the ABS of your case will be harmed. It could cause that your case look stained, shaded or even not good after doing the procedure so I assume no liability for a good result.
Preparation
At first you need some things to start:- Brush
- Gloves
- Safety goggles
- Glas or ceramic cup
- Creme developer(12% 40 Vol.)
- Cling film
- Old newspapers to cover your working area
You need to disassemble the whole Color Classic, which is described on my page teardown.
Remove logo
Because the hydrogen peroxide would bleach the rainbow color Apple Logo on the front it has to be removed. You can easily stick with a small screwdriver or something similar to the hole from the back and it will flip out. Hold it from the front because when you loose it you won't find a new one - they are very rare.
Laying the field
To prepare your workspace put a piece of cling film under the the Color Classic case.
'Painting' time
Fill a little bit of the creme developer into the cup, then you are ready to spread the creme developer evenly onto the case.
Take care to put it on the whole outside of the case.
Packing
If everything is well covered put another piece of cling film on top of the case.
Flip it to the back so the package is closed and no air is coming into the package.
This is important because otherwise the cream will dry out.
The sun
Now just easily put it into the sun. Have a look on it the whole time and watch out for the bubbles.
I got the problem later, that the bubbles did some ugly shades on the case. Try to stroke them away.
I do this in the hot summer sun at 30°c. In this hot temperature the creme will build some bubbles - take care of the case the whole time so you can brush away bubbles at the time they appear.
If you do this in winter or on a cloudy day you can use a UV lamp too, but these things cost money and it take much longer. If its possible use the sun - it costs nothing.
Time is working for you
At about 45-60 Minutes you will see a clear difference. I let the case sit about 2 hours in the sun.
The time depends on how warm and sunny the day is. The hydrogen peroxide is reacting with the UV light from the sun. Its easy: the more sun, the faster it works.
Its up to you to determine when it looks good and you peel of the film.
After you peeled it of you easily can wash it with cold water and dry it with a towel.
Shades of grey
As I mentioned before: watch out for the bubbles either you will see something like on the photo.
But its not to late - theres a method to get rid of these ugly stains.
Finishing
The get rid of the stains just easy put it back into to sun - now without the cling film. Put the developer cream directly onto the case and spread it evenly. Every few minutes take a little bit of the creme developer and brush it onto the case. Be aware that the creme doesn't dry out.
It took me about 20 Minutes and the stains are gone.
Complete
After the procedure I got a little sun burn in my face but a really nice looking case. The only thing to do is to flip in the Apple logo back in, erasable the computer and you are done.
You see in the photo the whole case. I explained it just for the front but you easily can adopt it for the whole case.