| [GMCnet] Re: Yellowed interior shell [message #363832 is a reply to message #363831] |
Wed, 05 May 2021 18:14   |
Rob
Messages: 651
Registered: November 2013
Location: Victoria, BC
Karma:
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Senior Member |
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The Vintage Apple Macintosh folks also restore their old cases using a
similar method:
https://www.youtube.com/watch?v=_ewI7nMgrB8
Rob
Victoria, BC
76 Royale - Rear Twins/Dry Bath
On 2021-05-05 2:12 p.m., Mark Sawyer wrote:
> Well.... Not sure what kind of plastic the GMC shells are... But if it is ABS, the Starwars reenactors may have you covered:
>
> https://www.instructables.com/Restoring-yellowed-Stormtrooper-armor/
>
> Story I read was there were some Starwars cosplay people that also happened to be chemical engineers specializing in plastics. They got together on
> some Starwars internet forum and actually did some chemical analysis on the yellowed storm trooper helmets(took the helmets into work and ran them
> through some sort of chemical analyzer)
>
> Anyway, they supposedly came up with this method of using an oxidizer and sunlight to undo the yellowing.
>
> Here are the Cliffs Notes:
>
> The yellowing of ABS when exposed to Ultraviolet light is the result of a flame retardant added to the plastic during the manufacturing process. The
> most common of which is tetrabromobisphenol –A, or TBBP-A. When exposed to UV light the TBBP-A degrades allowing Bromine to become a free radical.
> The bromine forms a bond with readily available oxygen and causes the yellow color.
>
> By irradiating the ABS with UV light in the presence of more hydrogen atoms, in the form of hydrogen peroxide, we break the bonds between the oxygen
> and bromine and allow the bromine to bond with the hydrogen, thus reversing the discoloration.
>
>
>
> To me, that right there is the internet at it's finest....
>
>
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Rob -
Victoria, BC -
76 Royale - Rear Twins/Dry Bath
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