How to prevent yellowing of equipment on display

Martin Goldberg wgungfu at gmail.com
Tue Sep 21 17:12:21 CDT 2010


Chuck - the yellowing has to do with a breakdown of the flame
retardent in the plastic.  The bromine free readicals involved in the
breakdown look for Oxygen to attach themselves to.  Per the chemical
engineer that came up with the Retrobrite process:

"Retr0bright reverses the yellowing process, it's not a permanent
cure. If the surface of the plastic is still open to the air, it will
yellow again, as the bromine free radical reaction is reversible
(otherwise, we wouldn't be able to reverse it...  )

The permanent fix it is to coat it with clear satin acrylic lacquer to
seal the surface off from the air. No oxygen, no oxidation; simple,
really......"

The chemical reaction of the breakdown process as well as the recovery
process are well documented at the Retrobrite wiki:

http://retr0bright.wikispaces.com/

Hope that answers you question.  I've used the process on several
items myself about two years ago (Apple III case, white bally computer
case) to great success.  So far no degradation of the plastic, and no
re-yellowing.


Marty

On Tue, Sep 21, 2010 at 12:26 PM, Chuck Guzis <cclist at sydex.com> wrote:
> On 20 Sep 2010 at 16:48, Martin Goldberg wrote:
>
>> It's usually the oxygen that's involved in the breakdown.  After
>> Retrobrite, it's recommended to spray them with a light sealant like
>> satin acrylic lacquer.  (Note that this is not a heavy paint on
>> lacquer like people think of with lacquering a piece of furniture).
>> Same thing used in some art communities to protect paper projects,
>> paintings, etc.
>
> Do you have a reference for this?  The literature that I've seen
> pretty much faults the stabilizers and plasticizers as well as
> outgassing of same.
>
> I'd think that if a simple lacquer coating worked, museums could save
> a lot of money by not pursuing grants and holding conferences,
> publishing papers and books and generally agonizing about the
> subject.
>
> FWIW, I've used a product called "Midas Finish Seal Lacquer" marketed
> by Rio Grande (the jewelers' supply house).  It's primarily used to
> seal jewelry finishes for display and can be easily removed.
>
> --Chuck
>
>
>



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