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Post by archimed on Feb 26, 2009 12:43:47 GMT -5
This has to be the coolest thing I've seen in retro computing/gaming in several years. A bunch of people in a thread over at the VC forums have been working on a solution for our ubiquitous yellowing cases. Sounds like they finally cracked it with the help of a professional chemist who looked into the problem more theoretically. Their results (so far) are really, really, impressive. The thread: www.vintage-computer.com/vcforum/showthread.php?t=14369UPDATE - post #5 at the above link has the 'best known' recipe for grey/white plastics that have went yellow. Do NOT use this process for dark/black plastics, just in case there is some bleaching. Read the entire thread before attempting it on your Mac 512
The official wiki that has some photos of the "retr0bright" process: retr0bright.wikispaces.com/The recipe is super simple - I don't think it has anything that you can't find easily locally. I plan on trying it out on a TRS-80 CoCo3 and NES that have yellowed over the years..
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Post by relayer on Feb 27, 2009 9:19:45 GMT -5
I'd be very interested in trying that on my original VIC-20. It's a very old piece (made within six months of the US introduction). Got quite yellowed after all this time. It was originally bright white with a smooth shiny surface.
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Post by David Murray on Feb 27, 2009 13:47:23 GMT -5
Wow.. this seems too good to be true. I would say half of my collection could benefit from this treatment.
On the UV lamp aspect, it wasn't mentioned whether it needed to be UV-A or UV-B. One type is easy to find, such as a fluorescent black light. They are also relatively safe to use. The other kind (like the ones used in EPROM erasers and water filters) are hard to get and dangerous to use.
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Post by relayer on Feb 27, 2009 15:00:40 GMT -5
Reading the details on the wiki page, it seems UV-A works as it causes the Bromine to get active and seek out an bind with the oxygen in the plastic.
That's how it yellows. Luckily enough, the same UV energy will re-activate the Bromine. However, the Hydrogen Peroxide in the mix to restore the plastic will provide Hydrogen for the Bromine to bind with. It's a much tighter bond and won't re-yellow as easily as it did before. Most "black lights" you buy for the glowing things around the house is UV-A.
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Post by David Murray on Feb 27, 2009 15:38:49 GMT -5
Then what is the purpose of the "oxy" detergent in the solution. You'd think that would just be providing more oxygen for the bromine to bond with.
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Post by David Murray on Feb 28, 2009 11:59:57 GMT -5
Okay. I'm ready to give this a try on my yellow VIC-20. I bought some hydrogen peroxide and some oxy-clean. I also bought a large fluorescent blacklight. The only thing that bothers me is that nowhere on the page does it say how to create this "gel" and since the VIC-20 case is a little large to just submerge in something, I'm going to have to try something else. My plan is to keep it under the blacklight and I've put the solution in a spray bottle and I'm going to just periodically spray it to keep it wet. I've covered half of the VIC-20 so I can see if it made a difference.
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Post by David Murray on Feb 28, 2009 19:17:39 GMT -5
Well, I did this for 30 minutes and there was no visible difference. I suppose I'll have to figure out a way to immerse it.
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Post by relayer on Feb 28, 2009 23:40:21 GMT -5
Then what is the purpose of the "oxy" detergent in the solution. You'd think that would just be providing more oxygen for the bromine to bond with. According to the Wiki, the Oxy stuff speeds up the process that breaks down the hydrogen peroxide. This releases Hydrogen molecules that form a stronger bond with the bromine than the freely available oxygen. In the end, the oxygen that bonded with the bromine is replaced by hydrogen. They chemical concept is explained it great detail on the Wiki. Interesting reading. As for mixing the stuff, you might have to look at the forums associated with it. There are recipes people use to make the gel stuff. Otherwise, you need to blend the liquid in a blender as detailed in the wiki, and create enough to immerse the item in. And the whole de-yellowing process takes a day or two.
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Post by mika73 on Mar 1, 2009 5:15:00 GMT -5
Funny things happends for Vic20 ;D
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Post by archimed on Mar 2, 2009 14:47:05 GMT -5
Well, I did this for 30 minutes and there was no visible difference. I suppose I'll have to figure out a way to immerse it. Immersion isn't likely the problem - I'm guessing a couple of things: (a) that you used low power peroxide (they recommend getting commercial strength - 10% or up to 30% solution), (b) that 30 minutes is not long enough. Some people put their machines out in the sunlight for 10 days. This point is the *best known technique* right now.. which I'm sure will be improved over time: www.vintage-computer.com/vcforum/showpost.php?p=90439&postcount=5Looking forward to seeing your results in the future. When I find some Xanthan gum and glycerin locally, you bet I'm going to dip all of my machines!
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Post by David Murray on Mar 2, 2009 22:05:05 GMT -5
Archimed, the picture of the C64 case on the main website said it was done in 8 hours. And it was a drastic difference. So I would have thought 30 minutes would have been enough to see some kind of change, even if miniscule.
But. You are also right about the peroxide. I always assumed if you bought a bottle of H2O2 that every molecule of liquid in the bottle would be H202. But, apparently mine is only 3% strength. So Yeah, I may have to find some higher strength version. While I'm at it, I might as well find that Xanathan gum too..
The sad part.. I mean really sad part, is when I got up in the attic and started looking for some of the computers that were really faded I realized I had thrown them away years ago. I had gotten frustrated with the ugly looking plastics so anything that I had multiple of, I threw the faded ones out. So my VIC-20 is the most faded unit I have, and it isn't really all that bad compared to a lot of them.
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Post by schism on Mar 3, 2009 16:18:26 GMT -5
If anyone is interested this made hackaday
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Post by David Murray on Mar 3, 2009 18:15:27 GMT -5
If anyone is interested this made hackaday Yeah.. but it also made slashdot. Millions more read slashdot than do hackaday.
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Post by racob on Mar 3, 2009 22:30:25 GMT -5
David: Can't help to notice your "Spotless" bath tub..I wouldn't even consider putting some other chemicals in it.
On this topic, there is a thread in English Amiga Board where the "peroxide" thing was mentioned being used to take out the yellowish color. However , there is also a "big" caution about how dangerous it is ...make sure to protect your eyes from any contact with the solution...
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Post by David Murray on Mar 4, 2009 8:55:06 GMT -5
David: Can't help to notice your "Spotless" bath tub..I wouldn't even consider putting some other chemicals in it. The two chemicals in question, if anything, would only make the tub cleaner and more sterile. So I can't see any harm. It rinses right down the drain.
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