Cleaning Stained Plastic/Ceramic Chips (BJ v7) (2 Viewers)

[upNdown]

Just to recap, here's a really brief summary of the issue followed by my own tests/results.

The yellowing of ABS plastics is caused by oxygen interacting with one of the molecules in the plastic. The oxygen atom bumps some stuff out of the way, there's a floating free radical, bada-bing, a new polymer is formed. This new polymer is just on the surface of the plastic. It absorbs some visible light (the yellow kind), the rest bounces off, and boom, you have a thin layer of yellow on the surface. Heat / UV can speed this process up, but it will happen regardless.

Retro-briting is the process of undoing this by redoing it. Using hydrogen peroxide, the weak oxygen atom gets busted loose from the peroxide, nudges its way into the yellow polymer, forms yet another polymer (with better bonds!), and essentially bleaches the yellow compound. The new polymer reflects all light, hence it's white. Heat/UV can speed this process up.

So, eventually, this means that it is possible for the yellowing to return as atoms get shared like a cheap hooker. But, at the very least, without direct sunlight and heat, it will take a very long time.

But this also means that it's not the gas (oxygen) by itself which is helping to retro-brite. You can totally submerge the chips in the peroxide with the same (if not better) results.

Method​	Time​	Result​
3% Hydrogen Peroxide	Very Long (24+ hours)	Virtually no change
3% Hydrogen Peroxide + UV Light (UVA)	Long (12 hours)	Very Good (VG) Whitening
3% Hydrogen Peroxide + Heat	Medium (8 hours)	Very Good (VG) Whitening
3% Hydrogen Peroxide + UV-A/B/C (Sun) + Heat	Shortest (6 hours)	Very Good (VG+) Whitening

Things that could REALLY help this process along:

• Using a higher concentration (like 12%) of hydrogen peroxide
• Combining a heat source, that is not the sun, along with UVA light (UVC is not the best for plastics)

Here are some of the variations I performed (all with 3% hydrogen peroxide)

• Sealed glass container in direct sunlight
  • Chips suspended by magnets so they did not touch the solution
  • Chips submerged in the hydrogen peroxide
• Sealed glass container at room temperature for 24 hours with chips submerged
• Black plastic container in direct sunlight with chips submerged (basically no UV, but heat)
• Open glass container at room temperature with direct UVA light for 24 hours

This all kind of needs a formal write-up. But the BIGGEST takeaways are:

• 3% hydrogen peroxide seems sufficient for this process and seems safe for full chip submersion in the liquid
• Heat and/or UV speed the process along; either works well, both work slightly better than either alone.
• 6 hours seems to be where the additional time has a deminishing effect.

What Would I Do in the Winter?
Without a combination heat/UV source like the sun, I would most likely use my UVA lights at room temperature. It would take longer, but the 1 test I ran produced results that I was happy with.

Did You Really Heat Hydrogen Peroxide?
I can just see the headlines now. "East Windsor man blows up house trying to whiten Borgata poker chips. When approached for comment, he was being carried off by men in white coats while yelling at them about the differences between inlays and labels." Yes - I did it heat it; outside on a hot plate. With those loose oxygen atoms, I'm not taking any chances here ... It was heated under an SPF-80 awning in the shade at around 75 degrees.

This is really cool! We should have PCF awards for this sort of thing. You deserve two.
Also:

 

[BearMetal]

Things that absorb yellow light do not look yellow. Things that reflect yellow light look yellow. But the point is made, that the yellow color arises from degradation of the plastic, and you can undo that chemical degradation with UV + hydrogen peroxide.

OMG, that's so embarrassing. Yes, that is what I meant. Obviously we have to have our optic nerves observe the visible light which is reflected back to us to see the color. Black absorbs all, hence we can't see it. I'm going to fix my post.

I actually think I got all twisted around looking at molecule chains to try to figure out what the butadiene turned into and why yellow was the result. But, alas, you're right - its reflected.

 

[BearMetal]

This is really cool! We should have PCF awards for this sort of thing. You deserve two.

Thanks! I hope that this helps some PCFers retrobrite some seriously yellow chips. It was a fun experiment and I really wasn't expecting this to be the solution.

 

[upNdown]

So has anybody tried this on clays? Do you thing the science is applicable? I assume Paulson clay has some plastic in it - maybe it’s as much plastic as it is anything else?
These whites are clean as hell. But they’re in various states of not quite brand new white.

 

[BearMetal]

So has anybody tried this on clays? Do you thing the science is applicable? I assume Paulson clay has some plastic in it - maybe it’s as much plastic as it is anything else?
These whites are clean as hell. But they’re in various states of not quite brand new white.

I don't think that it would work. Plastic, specifically ABS, has a compound called Butadiene (the "B" in ABS) which is what reacts with oxygen to form a new compound which reflects the yellow. Even if Paulsons included plastic in their formula, I would doubt it's ABS.

 

[ChipTalker]

I did some testing to try to remove red color transfer from Sunfly hybrids but did not seem to work from my limited time trying.