Retrobrite Experiment

Master X

Member
Jan 11, 2024
74
100
41
Lodi, WI
My retrobright experiment starts tonight. For those of you who are not familiar with this process I clipped this from wikipedia.

Retrobright (stylized as retr0bright or Retrobrite[1]) is a hydrogen peroxide-based process for removing yellowing from ABS plastics.

Yellowing in ABS plastic occurs when it is exposed to UV light or excessive heat, which causes photo-oxidation of polymers that breaks polymer chains and causes the plastic to yellow and become brittle.


The purpose of this is to see what will happen to a clear dome or lense that has yellowed from UV over the years and see if this can be reversed. All the sanding and the polishing in the world can't get the yellow out of the plastic.

I'm using 1 Gallon of hydrogen Peroxide 18% aqueous solution along with a heater on a temperature controller for the water. This is inside a UV box I built based of Odd Tinkering's video.


The control will be a Jetstream clear center lense that has for lack of a better word turned yellow.

I'll check back tomorrow to see what the results are.
 

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So the results are in, and I'm quite pleased with the way the lens looks now. The photos show the yellowing is mostly eradicated. This of course isn't a permanent fix as continued UV exposure from the sun will fade the lens back to yellow even faster. But if your lightbars are purely for display in a room and not exposed to sunlight then this should last for quite some time. I still have to wet sand and polish and UV clear coat the lens but I think this is doable even for the larger clear lenses that have yellowed.

I should mention the Aqueous solution is 12% hydrogen peroxide and not 18% as previously stated. After sanding, polishing and coating I'll upload the results.
 

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So the results are in, and I'm quite pleased with the way the lens looks now. The photos show the yellowing is mostly eradicated. This of course isn't a permanent fix as continued UV exposure from the sun will fade the lens back to yellow even faster. But if your lightbars are purely for display in a room and not exposed to sunlight then this should last for quite some time. I still have to wet sand and polish and UV clear coat the lens but I think this is doable even for the larger clear lenses that have yellowed.

I should mention the Aqueous solution is 12% hydrogen peroxide and not 18% as previously stated. After sanding, polishing and coating I'll upload the results.
After wet sanding and applying UV clear coat I think it turned out pretty decent. Now I need to see what will happen on an outer Jet series clear dome.
 

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Here is a better comparison of the Large dome and the center dome. I will try to do the large dome next.
 

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After sanding and polishing the domes are finished, at least as far as I can go with them. There is some crazing on one of the domes but not very noticeable unless viewed at the right angle. Is it worth to retrobright? I would say yes if you want to remove the yellowing without using invasive procedures. It took about 5 gallons of 12% hydrogen peroxide to fully submerge the domes to retrobright.
 

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