| Re: Yellowed interior shell [message #363831 is a reply to message #363829] |
Wed, 05 May 2021 16:12   |
TR 1
Messages: 348
Registered: August 2015
Location: DFW
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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....
Mark S. '73 Painted Desert,
Manny 1 Ton Front End,
Howell Injection,
Leigh Harrison 4bag and Rear Brakes,
Fort Worth, TX
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