Retrobrite

WARNING: You are warned that hydrogen peroxide is very nasty stuff and can cause severe chemical burns to skin and can also cause blindness if splashed into the eyes, if handled incorrectly. Usually, you can't buy stronger than 12% over the counter, as this is the maximum strength sold to the public and is used to bleach hair. If you want to try this, I would strongly suggest that you wear goggles and gloves to protect yourself.

Retr0bright Project

Anyone who has dug their old computer or console out of the cupboard or loft for some retro gaming will probably have noticed that it maybe hasn't worn too well with the test of time. The plastics these machines were made of is called ABS and to make it flame retardant (just in case it catches fire after a marathon session) the plastics manufacturers added chemicals that caused the plastic turn yellow or, even worse, brown over a long period of time.

It was originally thought that the yellowing was permanent and that the only solution to this was to paint the plastic in its original colour and cover the problem up. However, a chance discovery was made in March 2008, by The CBM Museum at Wuppertal in Germany (http://www.forum64.de), that immersing parts in a solution of Hydrogen Peroxide for a few days could partially reverse the process. This was initially taken up by the Amiga community in Germany (http://www.a1k.org) and the idea eventually found its way to the English Amiga Board (http://eab.abime.net), where a madcap collection of chemists, plastics engineers and retro hackers managed to perfect this concept and put it on steroids, with help from other forums.

Dave Stevenson from Manchester, UK, aka 'Merlin', the chemist behind the project, explains. "I came across the use of peroxide in July 2008 when Kristian95 told us over at EAB about what people like AmigaGTI were doing with it over at a1k.org. I was intrigued by this, as I am a former industrial chemist. I am also a plant Safety Manager by trade and, purely by coincidence, around that time I read about a dust explosion that had occurred in the UK with a chemical called TAED, which is the booster in the 'active oxygen' laundry products."

"This got me thinking, and after some really 'full-on', serious chemistry discussions with other EAB members, like Rkauer in Brazil, who is a plastics Engineer and my good friend Zetr0 from Kings Lynn, Norfolk, UK, who endured endless phone calls from me, we wrote some epic threads on English Amiga Board about the possible causes of the yellowing and eventually we arrived at the theory that it was the Bromine in the flame retardant that was the cause. We also knew that Ultra Violet light was another major factor. Having identified the culprit, the next stage was to try to develop and perfect a means of treating the plastic and reversing the yellowing quicker, without causing damage to the plastic. Being a former industrial chemist helped me tremendously, in understanding what was going on at the molecular level and to develop a treatment process to reverse the effect."

The problem was finally cracked in late July 2008 with a mixture of hydrogen peroxide, a small amount of an "Oxy" laundry booster as a catalyst and a UV lamp; we believed that this could do the job in hours instead of days. Proof of this concept was demonstrated on EAB by Tonyyeb from Hull, UK, Chiark from Leeds, UK and myself. The original test I did as proof of concept took two hours, as opposed to up to the five days it took for the original tests at CBM and a1k.org. We were on to something!!

Recipes

Merlin's Original Recipe

Items Needed

1. 1 pint (500ml) - Hydrogen Peroxide, 10 to 15% strength (40 vol) (available from hairdressers' supplies, e.g. the 'Sally Beauty' franchise in the UK)
2. 2 heaped tablespoonfuls - Xanthan Gum (available from health food shops or online)
3. 1 level teaspoonful - Glycerine (available from pharmacies)
4. 1/4 teaspoonful - "Oxy" laundry booster

Steps

1. Add the Hydrogen Peroxide and Xanthan Gum to the blender or liquidiser.
2. Mix on high speed for 5 seconds.
3. Add the Glycerine and mix for a further 5 seconds.
4. Let the mixture rest for a minute then mix again for 5 seconds.
5. A smooth, non-drip gel should have formed.

This gel can be put into a dark coloured jar or tub (e.g. a coffee jar covered in tape) and stored, as long as you DON'T add the "Oxy" until you are ready to use it.

Lorne's Variant Recipe

Lorne at Vintage Computer Forums prefers to use stronger Hydrogen Peroxide and his variant recipe is below.

Items Needed

1. 1/2 pint (200ml) - Hydrogen Peroxide, 30% strength
2. 2 level teaspoons - Xanthan Gum
3. 1 level teaspoon - Glycerine
4. 1/4 teaspoonful - Oxy laundry booster
5. 1 teaspoonful - hot (not boiling) water

Steps

1. In a very small ceramic or plastic bowl/dish, dissolve the Oxy in the hot water.

• Lorne found that the Oxy doesn't want to dissolve in the paste/gel very well - this premixture of the Oxy fixed that problem.

1. While the Oxy is dissolving, mix the Hydrogen Peroxide and Xanthan gum in the blender for five seconds.
2. Add Glycerine to that mixture and blend for another five seconds.
3. Let mixture sit for five minutes.
4. Blend for another five seconds.
5. Just before you apply the gel, thoroughly stir in by hand, the dissolved Oxy/water mix.

Tezza's Arrowroot Variant Recipe

Tezza at Vintage Computer Forums came up with a variation of the original recipe, based on another starchy food thickener called Arrowroot. Also, Tezza's recipe doesn't use glycerine. Trials have found the arrowroot-based paste dries out more quickly than the Xanthan gum/glycerine mixture in the recipes above and requires more frequent re-application. However, Arrowroot tends to be easier to find than Xanthan gum and is a workable alternative where this is the case.

The addition of glycerine may help to slow the drying processes but Tezza has not tried this at the time of writing.

Items Needed

1. 1/2 pint (200 ml) - Hydrogen Peroxide, 6% strength (available from most Pharmacies as a hair bleach or antiseptic)
2. 2 heaped tablespoonfuls - "White Crest" Arrowroot
3. 1/5 teaspoonful - "Oxi-Magic" laundry booster (to be added to the gel just before use, like the original recipe. Can probably be replaced by any "oxy-type" laundry activator.)

Procedure

If you use Arrowroot, you will need to heat the mixture. Don't worry, this is safe to do. Tezza suggests warming the mixture up in a microwave oven for about 45 seconds, based on a 750 Watt microwave oven, you may need to adjust the timings based on the wattage of your microwave. He strongly suggests that you do this in 15 second bursts and check the consistency after each burst. It's ready when is appears as a gel. Sprinkle in the Oxi-magic and stir vigorously with a spoon. This will also help thin the mixture so it can be brushed on.

Foaming when adding Oxi-Magic is related to how hot the mixture is and the concentration of peroxide. Usually the foaming is mild but if ithe mixture is hot and higher concentrations of peroxide have been used, the reaction can be vigourous. It would pay to let it cool first.

Other Gelling Agents

Other starchy thickeners such as corn starch, guar gum or even wallpaper paste may work. If you find another thickening agent that gives good results for you, let us know via the discussions tab and we will add your recipe to the Wiki.

Other Ingredients

If you decide to try other ingredients which have not been mentioned here, please be aware that you are out on your own and we cannot be held accountable for the results. Hydrogen Peroxide can react violently with some materials and you are strongly advised to do some reading around and research first. The recipes stated above have been thoroughly tested and are safe to prepare as long as the instructions are carefully followed.

If buying hydrogen peroxide from a pharmacy or hairdressers, check to make sure it has no other additives. All you want is diluted hydrogen peroxide (typically 3% to 12%). Additives may lead to unpredicable results. Lorne has tried a hair bleach product and he found that a solvent called terpene was present in the list of ingredients; when this was tried there was some evidence of the product attacking the surface which was particularly visible on dark coloured parts. A picture of the problem is posted in the Problems and pitfalls section

Sources

https://retr0bright.com/