Question - restoring sun-discoloured ABS plastic?

[TerraHertz]

A beige-coloured plastic case on something I'm cleaning up has some fairly noticeable yellowing due to sunlight exposure. It's particularly annoying where there were stickers, that left patches of the original lighter colour plastic.

Some people here seem to be wizards at restoring old equipment, so I wonder if anyone has any ideas for how to remove the yellowing? I can easily live with the staining if I can't find a way to fix it without risk of making the case look worse.

It's this: https://www.eevblog.com/forum/testgear/new-toy-tek-tla614-logic-analyzer/

[krivx]

The vintage computer crowd use Retr0Bright http://retr0bright.wikispaces.com/

[G7PSK]

I have had some success with T-Cut which is a polish with a fine abrasive used in the car industry for buffing paintwork.

[robrenz]

That retrobright looks like it works real well especially on textured surfaces. The yellowing on the buttons of my Tek 7603 restore came off with just a light wet sanding on 6 micron diamond film. Silicon carbide paper would work just as well. Then a polish with plastic polish will give the final shine. So if you have something that would be easy to sand and polish it may be worth a try. The discoloration on the Tek buttons seemed to be on the surface only.

[David_AVD]

Some of the guys on the Aussie Arcade forum have cleaned up old gaming consoles with good results I believe.

[TerraHertz]

Retrobright - COOL! Thanks for the reference. Very interesting to read their work on the causes of the yellowing. I'd assumed it was due to UV-induced breakdown of the ABS plastic chains. But no....

Sanding is not an option since the surface has a fine texture, that I don't want to damage. Even just rubbing hard with a solvent-wet tissue to remove old sticker residue tends to 'shine' the surface in patches. The number of things I've put aside, waiting till I get around to setting up my big compressor and grit-blasting cabinet, grows.