Date   : Wed, 07 Dec 2011 22:53:51 +0000
From   : robert@... (Rob)
Subject: Beeb Cleaner?

On 7 December 2011 22:26, Tim Fardell <tim.fardell@...> wrote:
> I'm not saying it doesn't work, but I think it's probably just
> whitening the plastic, as opposed to reversing the yellowing process.
> It'll look better, but you're not necessarily going to end up back at
> the original colour.

When this procedure was first mentioned, I spent a lot of time reading
back through the threads and posts where it was developed.  The
browning is caused by bromine, and which was originally added to ABS
as a fire retardant, rising through the plastic to the surface and
reacting with Oxygen in the air to go brown..  The UV breaks this down
again, and the Hydrogen peroxide/TAED (Oxi) mix supplies a replacement
Hydrogen atom, which doesn't give the brown colour.

http://retr0bright.wikispaces.com/Ultra+Violet+Energy

Of course, I imagine that you can also see some bleaching effect from
the hydrogen peroxide itself, if it's strong enough or left on too
long..

Rob