How to remove yellowing from an old Atari case

[andym00]

This is why I advocated keeping everything on a windowsill indoors. The "wet" behaviour of the streaking is consistent with standard "blooming".

 

Hmmm, but I thought glass blocked UVB and let UVA pass, and that UVB was responsible for acting as the catalyst here ? Or something equally complicated which is unimportant given I failed Chemistry catastrophically.. Should have just listened, word for word

 

Anyway, not important really.. I had fun, caught the sun massively, spent the last 2 days drinking beer whilst nursing them, and have super soft fingers now, and more to come still as I probably destroy more innocent computers

 

I will have some fun with the 64 then (if nothing comes of it's overnight Peroxide bath), and see just how mental I can get it, and just how wrong it can go > In the name of experimentation..

 

I guess I was a little too impatient, and over-flushed with success from the VIC + Atari's.. So far, same methodology, same weather, same treatments worked out for the VIC, 65XE, XL (now it's feint bits have vanished with a run through the dishwasher), and the 400 came out trumps, just need to do the flap and clamp now I've got into the madly engineered shielding inside..

 

Sad the 64 let me down, but it wouldn't be the first time

 

Still, all good fun

[flashjazzcat]

This is why I advocated keeping everything on a windowsill indoors. The "wet" behaviour of the streaking is consistent with standard "blooming".

 

Hmmm, but I thought glass blocked UVB and let UVA pass, and that UVB was responsible for acting as the catalyst here ? Or something equally complicated which is unimportant given I failed Chemistry catastrophically.. Should have just listened, word for word

 

I never even took the exam in Chemistry. But if it didn't work through glass, I'd have a lot of yellow machines.

 

Anyway - occasional bloomed machines are rites of passage in the world of Retr0Briting.

[31336haxx0r]

The dissociation energy for a carbon-bromine bond is 288 kJ/mol. That makes about 4.783E-19 Joules per single bond. The energy E of a photon is E=h*c/{lambda}, where {lambda} is the wavelength, h is Planck's number and c the velocity of light in vacuum. Solving for {lambda} yields

 

{lambda}=h*c/E.

 

Putting all constants and the above calculated dissociation energy yields {lambda}=415.572 nm. As humans can see up to approximately 400 nm, you don't even need UV light to split that bond and glass windows are fine. Well that is if I dind't make a mistake in my calculation.

[andym00]

The dissociation energy for a carbon-bromine bond is 288 kJ/mol. That makes about 4.783E-19 Joules per single bond. The energy E of a photon is E=h*c/{lambda}, where {lambda} is the wavelength, h is Planck's number and c the velocity of light in vacuum. Solving for {lambda} yields

 

{lambda}=h*c/E.

 

Putting all constants and the above calculated dissociation energy yields {lambda}=415.572 nm. As humans can see up to approximately 400 nm, you don't even need UV light to split that bond and glass windows are fine. Well that is if I dind't make a mistake in my calculation.

 

That makes perfect sense then, even at this time in the morning, and answers why the glass makes no difference.. Thank you

There's a million and one questions still, but I'm not going to ask them.. Apart from one, which is why people had luck with UV lights when their filters block most of the light > 400 nm ? I assume they must just let through some light in the violet region 400-420 nm, which is enough to get things going ?

 

Anyway, I'll stop asking questions and just dismantle, clean, paint and stick it in the sun

[TheNameOfTheGame]

Hello,

 

Wonderful thread. I have a few questions. I am following the basic recipe for retrobrite: hydrogen peroxide, xanthan gum, glycerin and oxyclean.

 

1) I found a clear 'developer' at the local Sally Beauty that is 40 volume water and hydrogen peroxide *but* it has one other ingredient: 'phosphoric acid'. Wikipedia say one of its uses is "...used as a pH adjuster in cosmetics and skin-care products". http://en.wikipedia....Phosphoric_acid

 

I am trying to keep the formula as pure as possible. Here in the usa the pharmacies only sell 3% hydrogen peroxide and the regular 'creme' developer has a host of other ingredients.

 

Is the phosphoric acid going to have adverse effects? badges, ink, attacking plastic? I am no chemist so I have no idea. I appreciate any advice.

 

 

2) For the UV lighting..there seems to be 3 types of uv lights, uv-a, uv-b and uv-c. http://en.wikipedia....iki/Ultraviolet

Ultraviolet A UVA 400 – 315 nm 3.10 – 3.94 eV long wave, black light

Ultraviolet B UVB 315 – 280 nm 3.94 – 4.43 eV medium wave

Ultraviolet C UVC 280 – 100 nm 4.43 – 12.4 eV short wave, germicidal

 

From reading the thread most are using uv-b I think. Is there an optimal wavelength for this process so I can decide which light to get?

 

 

3) Is UV light reflected by mirrored surfaces? I want to make a lighted box enclosure with mirrored interior surfaces that will bounce the radiation around evenly, but I am not sure if this would be affective with UV.

Edited August 15, 2012 by TheNameOfTheGame

[flashjazzcat]

Dunno about the UV questions, but don't let the Peroxide near an XE badge - the paint WILL peel off. Perhaps that's down to the phosphoric acid.

[TheNameOfTheGame]

Yea, thanks for that, I am definitely gonna use the extra-clingy saran wrap on the badges like some people in the thread have done.

 

Dunno about the UV questions, but don't let the Peroxide near an XE badge - the paint WILL peel off. Perhaps that's down to the phosphoric acid.

[+wood_jl]

I used a fine artist's paintbrush to carefully paint around the badge (right up to it but not on it) with good results. I had masking tape itself pull some paint off a badge when I taped it once.

[flashjazzcat]

I had masking tape itself pull some paint off a badge when I taped it once.

 

Blu-Tac's pretty good, surprisingly enough.

[andym00]

Dunno about the UV questions, but don't let the Peroxide near an XE badge - the paint WILL peel off. Perhaps that's down to the phosphoric acid.

 

I'm not sure I noticed much difference even though I just slopped it on all over the badge.. But then I haven't paid a lot of attention to it's original colour really

 

Anyway, another Vic-20 on the boil today, along with a 1530/C2N and those god awful white Commodore joysticks.. This whole process has had the unfortunate side-effect of totally rekindling my love affair with the beautiful beautiful VIC-20 I feel like 12 when I look at the beautiful white thing again!

 

The XE family are pretty sexy too when they're all nice and shiny, before I get banned for too much VIC loving;)

[kogden]

I'm probably going to attempt to retr0brite my 400 and 800XL this weekend. Depending on the results, I may try the 600XL and 130XE soon as well.

 

Will the peroxide effect the clear smoked plastic on the XL's? Any danger of blooming with the black plastic? It's noticeably yellowed too.

 

The XE family are pretty sexy too when they're all nice and shiny, before I get banned for too much VIC loving;)

 

The XE is ok looking, nothing special. I prefer the XL's. The XE and ST were designed to be super-cheap to produce. It shows. The Atari 600XL is much sexier than a VIC-20 IMHO. Not saying the VIC is ugly, the Atari is just prettier. In a computing looks contest, I'd say the DEC PDP-8/e or the Cray-1 win.

 

However, if you go near somebody's Cray-1 or PDP-8 with a bucket of peroxide and they're likely to kick your ass! LOL

Edited August 17, 2012 by kogden

[Tezz]

I used a fine artist's paintbrush to carefully paint around the badge (right up to it but not on it) with good results. I had masking tape itself pull some paint off a badge when I taped it once.

You could try masking the badge with decorators masking tape, it has less "tack" to it to prevent lifting a painted surface. I've been using it whilst decorating recently. I've got several XE's and ST's in storage that need retrobriting, I hope to get some time to do them in the near future.

[kogden]

Well, I got some 40vol (12%?) peroxide and some brushes today..... got weird looks from the girl behind the counter at Sally Beauty Supply in town. She actually asked her boss if she could sell it to me LOL

 

OK, I'm going to assume using 12% peroxide as a mouth rinse and/or not wearing gloves is a bad idea. I'm no chemist, the only thing I know about peroxide is it reacts nicely with silver and in high concentrations can be used as a rocket fuel.

 

I've got a couple days to go before I can attempt this due to thunderstorms over the next couple days. So before I go slathering on peroxide.... is the cling wrap necessary if I keep an eye on it? I might be able to get away with less exposure than some. We get REALLY good sun here in South Carolina. It's also nice and humid.

[mimo]

On an XL you can maybe get away with using cling wrap, however, for the tiny cost I would wrap that sucker. It beats having to check that no areas have dried out every 3 minutes.

use gloves, it stings like a bitch if it makes contact with your skin.

wear goggles, really you don't want to be blind an unable to appreciate your good as new Atari

 

You don't need sun, just daylight, it can be through glass on a window sill. No lame excuses about thunderstorms

[atari8warez]

I am trying to keep the formula as pure as possible. Here in the usa the pharmacies only sell 3% hydrogen peroxide and the regular 'creme' developer has a host of other ingredients.

 

 

I am in Canada and regulations here are very close to USA, so you can't find higher concentrations of H2O2 in the pharmacies, however just a few weeks ago, I was able to get a 6% solution from one of those pharmacies and they sell it as hair bleach. Next time you're out just ask your pharmacist they may have a 6% solution.

[flashjazzcat]

Atari 800 cleaned with toothbrush, nailbrush, and CIF:

 

 

And following some light (one hour) peroxide treatment:

 

 

Remarkably, a single hour's exposure on the windowsill has removed the slight olive tinge on the case. I'm calling it a day now, since I don't want to risk blooming.

[IndusGT]

Would any of these work to reverse yellowing:

 

The first one claims to be a deoxidizer for headlights, is this oxidation the same process going on in our ataris?

 

eBay Auction -- Item Number: 130778563732

 

https://www.getwipenew.com/?tag=he|af&a_aid=OF&a_bid=1c771dbb&data1=114

[mimo]

No, no and no.

Just buy a 3 buc bottle of creme peroxide

[IndusGT]

No, no and no.

Just buy a 3 buc bottle of creme peroxide

 

Ok, it's settled then, thanks

[Greg2600]

Since many of these efforts are a few years old now, what is the consensus of the yellowing coming back or not? I see some have gone to using a plastics paint? Are those available in the exact colors, or are they being mixed?

Edited October 21, 2012 by Greg2600

[flashjazzcat]

They do re-yellow, sometimes slowly, and sometimes at alarming speed. However, anti-UV protectants have been found to work well at preventing re-yellowing (although this conclusion is less than scientific!).

[AtariLeaf]

Whats the best way to de-yellow keyboard keys without taking it apart? The reason I ask is, for a coco 3, only some keys yellow and its not just a matter of popping keys out. You take a coco 3 keyboard apart you better have 1000 tiny monkeys to put together a 1000 tiny parts again.

[flashjazzcat]

As long as there's nothing which is allergic to moisture in there and the keyboard is thoroughly (and I mean thoroughly) dry before it's plugged in again, it should be safe to just paint the whole keyboard in peroxide (that's what I do with Atari XE keyboards). After a quick look at a CoCo keyboard being dismantled on YouTube, I'd say remove the back plate, mylar and rubber cups and process what's left as a whole. However, I'm unsure what the peroxide will do to the darker plastic (test it first).

Edited October 25, 2012 by flashjazzcat

[tjlazer]

They do re-yellow, sometimes slowly, and sometimes at alarming speed. However, anti-UV protectants have been found to work well at preventing re-yellowing (although this conclusion is less than scientific!).

 

Yes I had a really yellow 65XE that I deyellowed and after like 6 months it was yellow as urine!

[AtariLeaf]

Yes I had a really yellow 65XE that I deyellowed and after like 6 months it was yellow as urine!

 

I've been reading these kind of experiences a lot on different forums about retrobrite. I may stay away from this "solution" for a while yet. I think we may all have to accept that yellow is just the way these things are going.