De-yellowing

[Jules Richardson]

On 08/22/2015 07:48 AM, Tothwolf wrote:
> On Sat, 22 Aug 2015, Jules Richardson wrote:
>> On 08/21/2015 05:28 PM, Evan Koblentz wrote:
>>
>>>> So, how does one de-yellow something?  I have a VT-100 and some other
>>>> gear that could use that process.
>>>
>>> Google for "Retr0brite".
>>
>> I've never tried the stuff - but is it a permanent fix, or does the
>> yellowing gradually come back?
>
> It almost always seems to comes back to some extent. De-yellowing
> treatments only work on the outermost surface of the plastic, and there are
> still plenty of free bromides just under the treated surface which will
> migrate outward. The re-yellowing (which may or may not be much less than
> the original yellowing) also occurs much faster than the original
> yellowing. Unless you can somehow eliminate all the free bromides from the
> plastic, de-yellowing treatments such as Retr0brite are just a temporary
> cosmetic fix.

I thought that might be the case, but thought I might be mistaken given how 
many people seem to rave about how wonderful this stuff is.

Within a museum context, where showing original factory condition is 
probably a desirable thing, have there been any studies to ensure that 
retrobright (or other treatments) don't cause any damage to the plastics 
(e.g. making the surface less resistant to scratches, or the plastic more 
brittle, say)?

Personally I quite like the patina of a yellowed machine anyway - being 
able to see how it sat in a room, or where stickers used to be and such; 
it's a minor thing, but sometimes it does tell a little bit of a story. 
Maybe in 20 years if I ever sell any of my collection I might consider it, 
but for now they may as well stay yellow :)

cheers

Jules