Discoloured Plastic

[Farmerpug]

What causes some pieces of white plastic in cars to turn yellow? The 305 has a few parts which have turned yellow, but when i removed one of the sun visors i could see the plastic behind is clean, the other 305 has clean plastic.

 

 

Is there any way to clean this?

[chaseracer]

UV exposure?

[jonathan_dyane]

Cigarettes

[UmBongo]

There's a product called Retrobrite that is used to restore discoloured plastic on Commodore computers.

 

The main ingredient is hydrogen peroxide.

 

According to youtube you can make your own.

[UmBongo]

As to why it happens...

 

Some plastics have a bromine based flame retardant added to them, organobromine, which is carbon bonded with bromine. Over time oxygen reacts with organobromine bonding with the carbon and freeing the bromine causing the "Yellowing" effect we all know and love. UV light simply acts as a catalyst.

[gtd2000]

We have programmable thermostats for each room in the house (underfloor heating) and they've all significantly yellowed too - it's a smoke free house as well....looks like we've been smoking 60 a day!

[PhilA]

Did this at the weekend to test.

 

 

Bottom left key stuck in the solution for a while.

It's a mix of hydrogen peroxide and Oxiclean powder (half a pint to half a teaspoon) and then with the plastic immersed, it's left in the sunshine. Ultraviolet light activates the reaction. On an overcast day you're probably looking at about an hour ortwo to get results. Check on it periodically because it will also begin to bleach the colorants put in the plastic to make it beige or gray. Rinse it off with water. Don't get the stuff on your fingers either...

 

Cheap and cheerful way of cheering up old plastic. It's a surface reaction. Some plastics begin to yellow again quickly, but most of the ones I've tried have cleaned up and stayed white.

 

Phil

[Station]

I didn't think this would ever work - I have an old Transformer 'Jetfire' which is yellow, will give it a go.

[PhilA]

Take care if it has any color other than white plastic. The peroxide will bleach them out and ruin the color. Like a bad hairdo.

You can mix the stuff up into a gel and leave it to sit on the affected areas though.

 

Phil

[pshome]

Tinkered a lot with this on the Tagora's ... as you know, they are made of brittle plastic that turns yellow and brown while you look at it.

After playing with varios recipies and mixtures ended up using 12% Creme Peroxide, like this: http://www.ebay.co.uk/itm/171513674000 .

You can apply it with a brush and it wont run off. It needs UV light to actually work. Just put the part  into the bright sun or use a UV neon light http://www.ebay.co.uk/itm/151446243993. Cheap UV bulbs didn't work, just not enough UV radiation. Be patient, it needs 10 to 20 days to work depending on how yellow or brown the part was.

 

Interestingly, it doesnt bleach it to pure white, actually restrored the original beige.

 

Tagora plastic door panel, treated just the right half of it to better see the result.

 

 

 

same procedure on the golden Tagora

 

[AlabamaShrimp]

I didn't think this would ever work - I have an old Transformer 'Jetfire' which is yellow, will give it a go.

I've got two that have gone yellow. Post some pics if it works

[Farmerpug]

Ill give this a go and see if it works, thanks for the tips,

UV light sounds about right but would smoking have caused it to happen quicker, the other 305s i have including the one which has sat in a field for well over 10 years dont have any yellowed trim.