Tag: sun

It’s a process used to restore old Yellowed plastic back to its original state. Or at least it’s a way to try to. Read on and I’ll explain.

(Here is my understanding of the ABS plastic Yellowing process. There may be slight inaccuracies for which i apologise. Please do your own research on the subject. Further enquiries may be needed to satisfy your curious minds!)

Anyone who has any dealings with items built in the 80s/90s such as me will have come across an issue, especially related to anything built with ABS Plastic, and that would be the common phenomena of “Yellowing”.

If you own a game console or toy with white ABS there is the good chance that all or at least some of it will have turned a shade of yellow,

ABS plastic – otherwise technically known by its scientific name of “Acrylonitrile butadiene styrene” is a thermoplastic polymer. This means that it becomes pliable at an elevated temperature and solidifies on cooling. ABS was a flame retardant material that was regularly used as a casing for computers, gaming consoles and similar items just in case they were to overheat and catch fire. It was also used in Lego bricks for some reason, god knows how these were meant to catch fire though!

The yellowing issue lay with a chemical used in the manufacturing process called Bromine. When exposed to UV light or excessive heat this caused the photo oxidation of polymers within the chemical to break polymer chains causing the plastic to yellow and become brittle.

Come on then, tell us what retrobrighting is..

Retrobright or retr0brite as it is stylised by the guys who discovered the process, is an approach to removing yellowing from these ABS plastics, a kind of bleaching process if you like. The original recipe for Rerobright was discovered purely by chance by the CBM Museum at Wuppertal in Germany in March of 2008. I’m not going to go into the finite detail in this post, however you can read all about it here at the original Retr0brite project site: The Retr0brite Project.

The process can be a little hit and miss, however there are a lot of documented cases of it working very well. There is a downside that the yellowing can overtime return, as this process only really whitens the surface problem whilst those old polymers are still breaking down deep inside the plastic where this treatment doesn’t reach.

The process

I’m only going to touch on the process here, there are many other detailed explanations available on line, that explain the process far better than i could, here is one for example from the “How to Geek” site. How to clean old yellowed plastic on retro computers and game systems.

I will explain the process briefly below, but in no way do i accept responsibility for the way you approach the process. That is down to you entirely and i suggest you read up deeply on the subject prior to attempting this process. You have been warned!

What you need

• The offending piece of plastic
• Clingfilm
• Paint brush or suitable application brush
• Protective gloves
• Eye protection
• 40 volume oxidising cream (Hydrogen peroxide, salon hairdresser strength.
• Sunshine (Hard to find here in the UK) or a UV lamp

For starters make sure the item you want to brighten is clean. Make sure you have eye protection and gloves on as the peroxide can cause skin burns and the last place you want it is in your eyes, believe me.

Lay down some cling film. Place your subject matter on the clingfilm. Apply some cream onto the object you want to lighten and smear it around ensuring the whole item is covered in the peroxide solution, failure to do this can cause blushing and streaking. When you are happy that the subject matter is fully treated, cover the whole item in the clingfilm ensuring there are no holes where the solution can evaporate from.

Next place the item where the whitening can take place. Out in direct sunlight and leave it there for the entire day. Indoors a UV light lamp can also be used. The UV rays that originally caused the yellowing will now react with the Peroxide to reverse the process. This does take time though and in some cases where the yellowing is particularly bad a second or third treatment may be required.

Remove the clingfilm after a sufficient UV exposure and ensure the subject matter is washed thoroughly to remove all traces of the peroxide developer. Again, ensure you have gloves on until all traces of the chemical are removed.

Dry the subject matter or allow it to dry naturally. Hey presto! Job done. And thats basically it.

I’ve covered this subject, as it is something i will be attempting over the coming months. I will address the process in individual posts relative to the item i will be working on at the time.

Thanks for passing by, it’s always appreciated.