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Removing yellowing from plastics - Part 2

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Lorne

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As I said earlier in one of these threads, to clean or not to clean, that is the question.
QUOTE]

I'm with you Merlin. If a computer is dirty, and you clean it with dishwashing liquid (or in the dishwasher like Tezza !), that's the same thing as we're doing.
We're just using a different liquid to clean away the dirt that's settled on the computer over the years.
Some like dirty computers, some like clean ones.
I like clean ones.
 

gerrydoire

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My Apple IIe

My Apple IIe

I have an Apple IIe that is grosely yellowed, like the case was put into a easy bake oven.

Interestingly enough, the cover, the portion that is not exposed to the light which is the very bottom part that slips under the front of the case is no where near as yellowed, which tells me light exposure does the most harm.
 

Lorne

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Interestingly enough, the cover, the portion that is not exposed to the light which is the very bottom part that slips under the front of the case is no where near as yellowed, which tells me light exposure does the most harm.

I noticed the same thing on my Osbornes and on my Televideo monitor. The inside doesn't yellow, just the outside. I used the inside colour/shade as a target for what the outside colour/shade should get deyellowed to. It's gotta be the UV rather than the O2, that causes the yellowing.
 

Merlin

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That's not too surprising, since the UV light excites the bromine molecules and would make them migrate through the plastic more than if no UV was present. It also would make the bromine much easier to attach an oxygen molecule to it.
 

tezza

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I have some yellowed Atari 130XL keys submerged in a H2O2/Oxy mixture out in the full New Zealand summer sun (highest UV levels in the world) as I type.

Hopefully there is a lot of bromine excitement going on!

Tez
 

Merlin

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If you look closely, you may be able to see bubbles form on the keys as the reaction takes place; there is a cracking photo in one of the threads on EAB that tonyyeb took of a key with bubbles all over it.

Here it is:-

picture.php


Cool, eh? :mrgreen:
 
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tezza

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Yep, that's exactly what's happened to mine. I'm into day 3 of a-3 day de-yellowing key cycle. It's working fine. I'll post some pics when everything's done.

Tez
 

gerrydoire

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If you look closely, you may be able to see bubbles form on the keys as the reaction takes place; there is a cracking photo in one of the threads on EAB that tonyyeb took of a key with bubbles all over it.

Here it is:-

picture.php


Cool, eh? :mrgreen:

I find it all amazing, brings back the natural beauty of the plastic..
 

tezza

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Experiences with yellowed Atari 130 XE keys

Experiences with yellowed Atari 130 XE keys

Some more de-yellowing experiences.

This time severly yellowed Atari 130XE keys left in the sun in a 6% hydrogen peroxide solution (with a 1/6th teaspoon laundry booster well stirred in).

2008-01-15-atari130xl-keyboard-de-yellow-process.jpg


The jar was left out in the sun for 3 days. The first couple of days the solution was quite active. By day three the mixture was almost spent as evidenced by the lack of bubbles. Each image below was taken at dusk with a flash.

Below are the keys laid out on a bench. The photo was take with a flash that really brings out residual yellow if there is any.

2008-01-15-atariXE-keys-spread.jpg


As can be seen the process hasn't ENTIRELY de-yellowed the keys. It's certainly gone a long way though as shown by the space bar, which was too large to fit in the jar hence wasn't done.

There is no evidence whatsoever of any pitting, fading of letters or damage to the plastic.

I figure the job wasn't 100% because of the relative weakness of the H202 (only 6%). It's also a little patchy perhaps because they were all jammed in a jar and the light intensity around each one wasn't consistent. I was originally going to lay them out in a shallow tray but couldn't find anything to stop them floating.

I'm going to make up a new mixture tomorrow and give them all another day or two. I have a feeling they just need a little more processing with a fresh mixture and all traces of yellow will be gone.

We shall see.

Tez
 

Merlin

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@ Tezza

Tonyyeb over at EAB found that Blu-Tack (the sticky putty stuff used to hold posters up) was ideal to make the keys sink in the solution and was re-usable. The "A" key in that photo above was weighed down with it.

That's a nice result on the keys considering; I am pleased you saw the reaction working then slowing down as the bromines were processed, it's a bit like a zip, eventually you get to the end.

I hope that this helps.
 
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tezza

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@ Tezza

Tonyyeb over at EAB found that Blu-Tack (the sticky putty stuff used to hold posters up) was ideal to make the keys sink in the solution and was re-usable. The "A" key in that photo above was weighed down with it.

Blu-tack, yes I know it. It's sold here.

The next project is to de-yellow an Apple IIe platinum case and keys. I'll give the blue-tack method a go. I'm assuming you stuff it inside the keys to make them heavy, rather than applying it to the bottom edges and trying to stick them to the bottom of the container?

Tez
 

Merlin

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Blu-tack, yes I know it. It's sold here.

The next project is to de-yellow an Apple IIe platinum case and keys. I'll give the blue-tack method a go. I'm assuming you stuff it inside the keys to make them heavy, rather than applying it to the bottom edges and trying to stick them to the bottom of the container?

Tez

As far as I know, Tonyyeb used it for ballast to weigh them down.
 

Merlin

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Tezza,

It looks like you have your ideal conditions all worked out :mrgreen:

What mixture did you use for that Apple case, and how long did it take?
 

tezza

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What mixture did you use for that Apple case, and how long did it take?

Same as before as detailed in this blog entry. The case spent two days in the sun and got about 4 coverings a day. I'm back at work, so Annette (my wife) kept and eye on it and re-applied a coat when needed. The IIe keys are still brewing in a dish today, on day two of a three day bath.

I'm pretty stoked with the results. I'll post full images of both the IIe and the Atari130 XE once their re-assembled. I've found a few issue people should know about though and will detail these in the next post.
 

tezza

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Keyletter and label fade

Keyletter and label fade

I found there can be some fading of keys on letters and labels with this process. It's minor and it only tends to happen when you overcook things.

For example on the images below. The top one show the case pre-treatment and bottom one after. The lighting conditions are different in each image but you can see the Option key has faded substantially.


2009-01-18-atari130xe-deyellows-key-option-key-before-treatment.jpg


2009-01-18-atari130xe-deyellows-key-option-key-after-treatment.jpg

Similarly, you can see in the photo below that the "N" key has faded also.

2008-01-18-atari130ex-deyellowing-keys-faded-key.jpg

Recall that these keys got a full FIVE days (24 hours a day) in two lots of peroxide solution. I was determined to remove all traces of yellowing. I did, but it was perhaps a little extreme.

Another example can be seen in the IIe case. You can see the label before and after. The label on the treated case is still quite readable but it has faded it a little.

2009-01-18-apple-platinum-deyellow-label-fade.jpg

I saw the process first hand when I inspected the case during the process and noticed one of the flakes of dried paste actually had an imprint of this lable in the flake itself. So something may well have been coming off.

So, what I'm finding is the process works very well, but you need to take some care with keys and labels. It seems to be a case of making sure you don't keep the process going more than you need to and finding a balance between removing the yellowing to an acceptable level, and not overdoing the treatment. With my Atari, in retrospect I would have been better to remove the keys that had already completely de-yellow at the end of 3 days (the select key was one of them), and only treated those that needed further treatment, rather than just keeping them all togther.

This whole thing is a learning process though.

Tez
 
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tezza

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Apple IIe and Atari 130XE de-yellowing process complete

Apple IIe and Atari 130XE de-yellowing process complete

Hi,

The Apple II Platinum and Atari 130XE deyellowing project is now complete. Here are the results:

2009-01-19-appleIIe-platinum-before-deyellow.jpg


2009-01-19-appleIIe-platinum-after-deyellow.jpg


2009-01-19-atari130xe-before-deyellowing.jpg


2009-01-19-atari130xe-after-deyellowing.jpg


Still just a touch of yellow in the Atari keys. This only shows up under the camera flash though. Note the shift keys in the Apple IIe (3 days in solution). A touch of bleaching/streaking there for some reason.

Just this Colour Genie to go now. And that will be it for my collection.

Then again...the spacebar on the Commodore SX could do with a pasting. Come to think of it the Amiga 500 and Atari 1040 aren't as original as they should be. That C64c doesn't look that white. Those System 80 keys are a little cheese coloured, aren't they?

Hmm...I could be here a while yet :)

Tez
 

Merlin

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OMG...you are becoming as addicted to this as Lorne is!!! :crazy: :wow:

This is the second documented case of major addiction to de-yellowing that I have come across. Now lie down on the couch and tell me about your mother.... :lol:

Now that I've created a whole new addiction, I need a name for it; any suggestions?

:mrgreen:
 

tezza

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OMG...you are becoming as addicted to this as Lorne is!!! :crazy: :wow:

Yea. And whose fault is that?? I didn't even mention all the monitors and printer cases. Lemma know your address so I can forward the rehab bill! :)

Naa, just seeking to make the collection look as good as it can. I think the de-yellowing projects will take a break for a little while though. At the retail prices of $14NZ ($7.20 US) a 500ml bottle of H2O2 and with at least two bottles needed for each computer (one for the case, one or two for the keys) there is a cost outside just labour in doing this stuff.

Well worth it though, if you have some old units you want to display eventually. In fact, it's worth doing just one anyway to see the amazing transformation.

Tez
 
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