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How to remove yellowing from an old Atari case


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#51 Merlin OFFLINE  

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Posted Fri Jan 30, 2009 7:41 AM

@ mimo

Don't be; I am a safety manager at a chemical plant and I don't want injuries to happen....besides, you can't "overcook" it if you use 10 to 15% as it isn't strong enough to attack the polymer.

Wear gloves and safety glasses / goggles when you do this, please!!

#52 Allan OFFLINE  

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Posted Fri Jan 30, 2009 7:53 AM

All I can find is 3% in a grocery store. What type of place would carry something stronger?

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#53 poobah OFFLINE  

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Posted Fri Jan 30, 2009 8:09 AM

Would the 3% grocery store stuff work given a longer UV exposure time?

#54 mimo OFFLINE  

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Posted Fri Jan 30, 2009 8:12 AM

All I can find is 3% in a grocery store. What type of place would carry something stronger?

Allan


I found it at a hairdressing supplies store in the UK, it is just peroxide for bleaching hair.

#55 mimo OFFLINE  

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Posted Fri Jan 30, 2009 8:17 AM

Would the 3% grocery store stuff work given a longer UV exposure time?

Quote from Merlin

You should be able to get 20% H2O2 easily from 'Sally' hairdressing trade suppliers, as it is used to bleach hair. You will also find up to 35% strength used in swimming pool chemicals and as a pet urine neutraliser in kennels. Lorne found it as something called "Urine Rescue".

Lorne used 35% but 20% would give the same effect. Weaker solutions just take a bit longer, that's all.


How much longer I have no idea, but it may be better to hunt down something a bit stronger, maybe from a drug store?

#56 Allan OFFLINE  

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Posted Fri Jan 30, 2009 8:23 AM

Would the 3% grocery store stuff work given a longer UV exposure time?

Quote from Merlin

You should be able to get 20% H2O2 easily from 'Sally' hairdressing trade suppliers, as it is used to bleach hair. You will also find up to 35% strength used in swimming pool chemicals and as a pet urine neutraliser in kennels. Lorne found it as something called "Urine Rescue".

Lorne used 35% but 20% would give the same effect. Weaker solutions just take a bit longer, that's all.


How much longer I have no idea, but it may be better to hunt down something a bit stronger, maybe from a drug store?

Thanks Mimo. I'll look around.

Allan

#57 mimo OFFLINE  

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Posted Fri Jan 30, 2009 8:49 AM

This may help, I got mine from the UK franchise of Sally
http://stores.sallybeauty.com/

#58 Merlin OFFLINE  

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Posted Fri Jan 30, 2009 9:00 AM

Some larger pet stores may carry it as well; it's called Urine Rescue (ewwwww....) and that is 20% strength.

Drug stores carry 6% strength as it is used as an antiseptic.

Edited by Merlin, Fri Jan 30, 2009 9:03 AM.


#59 harpo OFFLINE  

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Posted Fri Jan 30, 2009 9:12 AM

OK,
I will chime in here. Professionally, I have BS and MS degrees in chemistry and worked with polymers (plastics and such) for many years. I have not tried this protocol on my own cases that are yellowed yet, because I am just getting back into my old system while teaching my son some computer programming skills (what a great system for teaching programming :) ).
IMHO, the chemistry that is presented is valid for the mechanism of the "ageing/yellowing" phenomenon and how to reverse it.
When using the materials described be aware that if you don't follow the protocol TO THE LETTER you are out on your own and working with some potent chemical materials and can not be certain of the results you will obtain. I will reiterate what others have said, concentrated hydrogen peroxide is an EXTREMELY powerful oxidizing agent and can cause burns to the skin (I know from first hand experience), explosions when mixed with reducing agents (think rocket fuel), or damage to other materials it comes in contact with.
The 2% hydrogen peroxide you get at the pharmacy is not concentrated enough to accomplish this reaction. You need to use concentrations in the 12-15% range. You can start with the peroxide available at a beauty supply for bleaching hair but be careful to dilute it properly. If you do not know how to calculate the dilution ask for help! And "if a little is good, more must be better" DOES NOT apply here. The purpose of the EDTA from the Oxy is to act as a catalyst. A catalyst is an agent in a chemical reaction that reduces the energy required to get the reaction going. You want the catalyst to be "pushing" the reaction, not excess concentration of the peroxide. That is the beauty of the protocol developed. If you use the concentrations and the materials described you should get undetectable amounts of oxidation of the base polymer and only reaction with the bromine compounds. The other thing to remember is that the UV is VERY important. The UV breaks the weak bonds in the peroxide causing the formation of the active radicals. If you have an old "Black Light" pull it out and use it. Otherwise wait until you have a nice sunny day. And as soon as the yellowing is observed to be gone, remove the piece and rinse it thoroughly to get rid of all traces of the EDTA and OXY.
My feeling is that those individuals who have observed degradation and roughening of the surface of their plastic cases probably used too high a concentration of peroxide. If you stay on the dilute side and use the catalyst and UV so that only reaction with the bromine is favored, you should get an outstanding result.
As far as slowing the recurrence of the yellowing, I would suggest using a very light coating of ArmorAll or other surface protectant. It will slow the absorption of oxygen onto the surface and also reduce the amount of UV penetration slightly. It will have that slippery overly shiny feel and appearance that all surface protectants leave, but it will work to slow the recurrence of this phenomenon if that is foremost to you.

#60 Kilack OFFLINE  

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Posted Fri Jan 30, 2009 10:42 AM

For those asking where you can find higher concentrations of Hydrogen Peroxide. I found Swimming Pool suppliers often carry it ( @30% or 35%) 5 litre containers and it is cheap.
Then you just need to get distilled water to dilute it a bit, don't use tap water... and no splashing around with it, that stuff will destroy your sight, rubber gloves and eye safety wear are a must.

#61 Merlin OFFLINE  

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Posted Fri Jan 30, 2009 11:39 AM

@ harpo

Many thanks, kind sir, for the validation of the chemical process we have worked so hard to perfect in the last 4+ months; it has been a massive co-ordinated effort on a global scale, with people from the US, New Zealand, UK, Brazil and lots of others to test and perfect this. It's TAED (tetra acetyl ethylene diamine) by the way; a lot of people get it confused eith EDTA (ethylene diamine tetraacetic acid) - the two chemicals are somewhat different.

I am honoured that someone with possibly more chemistry knowledge than I is able to follow and validate the reasoning behind what we have achieved; you would not believe the amount of cries of "Heresy!" and trolling we have had to endure to get to where we have.

We are writing a Dummy's Guide to this process and it should be on a web page in a week or so. Stay tuned....

#62 mimo OFFLINE  

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Posted Sat Jan 31, 2009 3:39 AM

Here is the latest. Atari 400 from Dr Clu to replace my broken 400 case. It was slightly yellowed (looks worse under flash photography)
To give an example I only treated the main part of the top case. I left the cart flap untreated as a guide to what had happened.
You can see from the second shot that the main case is much improved.
8 hours under UV light, but at some point during the night it dried out. I will do a bit more on this case as I think it can go a bit less yellow.
400_before.jpg 400_after.jpg

#63 Merlin OFFLINE  

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Posted Sat Jan 31, 2009 5:34 AM

Good stuff mimo, once you have finished it, can you write your process conditions up here please?

Are you also a member of Atari Forums? If so, it may be worth posting some of your results over there; simbo trolled me something shocking about our work when I first posted it over there. Mind you, he couldn't back it up with a scientific argument.

Thanks

mmmmmmmmmmm........ hardware pr0n................:)

Edited by Merlin, Sat Jan 31, 2009 5:37 AM.


#64 mimo OFFLINE  

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Posted Sat Jan 31, 2009 9:27 AM

Good stuff mimo, once you have finished it, can you write your process conditions up here please?

Are you also a member of Atari Forums? If so, it may be worth posting some of your results over there; simbo trolled me something shocking about our work when I first posted it over there. Mind you, he couldn't back it up with a scientific argument.

Thanks

mmmmmmmmmmm........ hardware pr0n................:)

Yeah, I'm a member at Atari Forums, although I very rarely go on there.
I'll dig out an ST and do the process on that.

#65 Merlin OFFLINE  

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Posted Sat Jan 31, 2009 9:53 AM

I don't think simbo was having a go from the old "Amiga vs. Atari" point of view, it's just that I don't think he got the science part of it and when I tried to explain it, it all got a bit ugly. It's their loss anyway....don't go out of your way with this, eventually someone with a foot in both camps will point it out to him.

#66 atariksi OFFLINE  

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Posted Sat Jan 31, 2009 10:35 AM

Some larger pet stores may carry it as well; it's called Urine Rescue (ewwwww....) and that is 20% strength.

Drug stores carry 6% strength as it is used as an antiseptic.


So, ideally you want 20% (or less) H2O2 else plastic polymers will be affected or does that "magic" % depend on the plastic?

@ Mitch

Sure.

I used a polypropylene washing up bowl. If you make the gel version by adding corn starch, arrow root or xanthan gum to thicken the brew up so it's like hair gel, you can paint it on and just lay the part on a polythene sheet. Tezza at VCF used cardboard when he did his VIC-20 case.

...


Is the gel version safer to use than liquid version or is that also harmful to touch, smell, etc.?

#67 atariksi OFFLINE  

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Posted Sat Jan 31, 2009 10:50 AM

OK,
I will chime in here. Professionally, I have BS and MS degrees in chemistry and worked with polymers (plastics and such) for many years. I have not tried this protocol on my own cases that are yellowed yet, because I am just getting back into my old system while teaching my son some computer programming skills (what a great system for teaching programming :) ).
IMHO, the chemistry that is presented is valid for the mechanism of the "ageing/yellowing" phenomenon and how to reverse it.
...


But the whole plastic cover is aging not just the cover. So I suppose you are removing the surface yellowing by attacking the Br molecules.

#68 Merlin OFFLINE  

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Posted Sat Jan 31, 2009 11:28 AM

Only the areas that get exposed to UV light go yellow. If UV light can't reach the bromine molecules inside the case, they won't react. Simple.

The gel version is a lot cheaper than a bath full of liquid, especially for large parts. If you keep the strength of the peroxide between 10 to 15% you are less likely to get badly burned by it and you should always wear gloves and goggles when handling parts painted with the gel. Safety First!!

10 to 15% peroxide strength is too weak to damage the polymer, but strong enough to treat the bromine molecules. Tezza's 130XE earlier in this thread used 6% so it works at lower concentrations with no damage to the surface.

#69 Merlin OFFLINE  

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Posted Sat Jan 31, 2009 12:54 PM

This is amazing stuff.

I always thought once plastic had yellowed then that was it, that there never could be anyway of removing it.


You should never use words like "never" or "impossible"; they just mean it hasn't been cracked yet. Words like those put blinkers on your creativity.

I like "impossible", it's a challenge to me........ :D

@ atariksi

Don't use the word "but"; have a little faith and try it, you may amaze yourself.....

Edited by Merlin, Sat Jan 31, 2009 12:57 PM.


#70 Albert OFFLINE  

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Posted Sat Jan 31, 2009 1:01 PM

I just read this thread for the first time, and I have to say the results are pretty remarkable (especially for the 130XE and the Vic-20 that have been pictured). I have several machines I could apply this process to myself. :)

Merlin, please let me know when you get your detailed instructions page up and running and I'll post some news about this on the front page here..

Thanks!

..Al

#71 Merlin OFFLINE  

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Posted Sat Jan 31, 2009 1:13 PM

@ Albert

Absolutely, no problem; we have offered our article once complete to other sites and we are happy to do this. By the way, did you check out the C64 that I did the extreme test on to show what is possible, it's a lot worse than the Vic-20 and it was restored in eight hours.

It's here:

http://eab.abime.net...?t=37808&page=7 (I can't figure out this image posting thing on here lol)

I half masked it and treated the left side, for those who may be thinking of smart comments...... :D

Edited by Merlin, Sat Jan 31, 2009 1:14 PM.


#72 Albert OFFLINE  

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Posted Sat Jan 31, 2009 1:41 PM

@ Albert

Absolutely, no problem; we have offered our article once complete to other sites and we are happy to do this. By the way, did you check out the C64 that I did the extreme test on to show what is possible, it's a lot worse than the Vic-20 and it was restored in eight hours.

It's here:

http://eab.abime.net...?t=37808&page=7 (I can't figure out this image posting thing on here lol)

I half masked it and treated the left side, for those who may be thinking of smart comments...... :D

That looks great! At first I thought that maybe it had become too light, but then I found this picture of a nice, minty C64:

http://upload.wikime...Commodore64.jpg

..Al

#73 Merlin OFFLINE  

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Posted Sat Jan 31, 2009 1:47 PM

Nice... the colour once I had completed the treatment matched the inside that had never seen daylight.

The thing is, these bromine molecules are so reactive that they even may have turned the C64 slightly brown due to the moulding temperature, which was probably going to be around 130 to 160 Celsius. As the case cooled from moulding, it may have browned slightly.

It all makes perfect sense, once you work out the physics and chemistry of it.

#74 atariksi OFFLINE  

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Posted Sat Jan 31, 2009 4:33 PM

This is amazing stuff.

I always thought once plastic had yellowed then that was it, that there never could be anyway of removing it.


You should never use words like "never" or "impossible"; they just mean it hasn't been cracked yet. Words like those put blinkers on your creativity.

I like "impossible", it's a challenge to me........ :D

@ atariksi

Don't use the word "but"; have a little faith and try it, you may amaze yourself.....


If was using the word "but" with aging. I don't see any relationship with yellow removal and aging reversal; we can't just assume it's happening. People get plastic surgery done but their aging is not affected by it. It's true, you shouldn't give up by using the word "impossible" unless it's deductively concluded like being logically impossible.

#75 Merlin OFFLINE  

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Posted Sat Jan 31, 2009 5:14 PM

OK, I haven't assumed it is happening at all, as I researched this extensively. I carried out controlled experiments to prove the the effect only happened under UV light conditions. The only logical explanation for the effect is that the bromine molecules are excited by the UV light and the extra energy is enough to break the co-ordinate bond between the Bromine in the PDBEs and the Oxygen that attached to it. Do the experiment in the dark and you get nada, zilch, bugger all, nothing...

Bromine compounds are yellow / brown in colour; the higher the oxidation state, the browner they get. This is why the plastic goes yellow then eventually brown, as more of the Bromine molecules migrate to the surface and get oxidised. By protonating the bromine, we effectively re-cap the PDBE chain and take the Bromine back to it's lowest oxidation state.

This was the theory I postulated as being the mechanism involved and the one that Harpo verified as a fellow scientist as being scientifically sound.




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