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Removing yellowing from plastics - Part 2

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tezza said:
Yesterday and today I tried out the de-yellowing process on a Vic-20. It worked a treat!!. I found a simple food thickener made a great paste, and hydrogen peroxide solutions of only 6% (hair bleach strength) are sufficient. I've documented the experience in my blog.
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Thanks for that. I don't really have anything of significance to de-yellow, but your use of relatively easy-to-obtain ingredients inspires me to try it out.
 
carlsson said:
Wow, it really looks nice. Perhaps the strength of the hydrogen peroxide depends on which kind of catalyst you mix it with, or simply the strength of UV?
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I must admit, given that the peroxide was a low 6% and it was a cloudy day all day with no clear sunshine (so less UV than normal), I was pleasantly surprised at the result. I'd expected it would need a second day (and another mix) but after 8 hours it was about as de-yellowed as it could be!

It will be interesting to see how the other cases go.

If Merlin, or anyone with some chemistry background and a knowledge of this process, is reading this it would be interesting to know if the sodium percarbonate in the Oxi-magic IS the same as the tetra acetyl ethylene diamine in the Oxy mentioned earlier in this thread, or if it is another compound that catalyizes the same reaction (and is perhaps stronger?) ?

Tez
 
tezza said:
Hi,

I thought it was probably better to use this old thread rather than make a new one.

Yesterday and today I tried out the de-yellowing process on a Vic-20. It worked a treat!!. I found a simple food thickener made a great paste, and hydrogen peroxide solutions of only 6% (hair bleach strength) are sufficient.

I've documented the experience in my blog.

Cheers

Tez
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That was one uggly yellowed vic20.

So when is somebody going to complete this project and come up with a UV resistant non glossy coating that will keep systems you just cleaned from turning yellow again in a year?
 
Unknown_K said:
That was one uggly yellowed vic20.

So when is somebody going to complete this project and come up with a UV resistant non glossy coating that will keep systems you just cleaned from turning yellow again in a year?
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Since the process neutralizes the bromide radicals in the fire retardant, theoretically, it shouldn't yellow again.
 
A couple of other cases

A couple of other cases

I've recovered enough from New Year's eve celebrations to continue my de-yellowing binge today.

My Atari 130XL

2009-01-01-atari130-case-before-and-after.jpg


This was another complete success like the Vic-20

My cheese-coloured RX-8800

2009-01-01-rx8800-case-before-and-after.jpg


Acceptable, but no where near as even as the Vic-20 and Atari130XL.

Check out the full details and reflections in my latest blog.

Tez
 
I might try that with my 1040ST (same color plastic as that 130xe) because it is yellowed and now with a non yellowed mono monitor the yellowing REALY is starting to bug me.
 
Maybe it has been mentioned before, but don't regular solariums emit UV light of the right wavelengths? If not, perhaps the lamps can be exchanged to ones that do, in case people already own half or full body solariums in their homes.

As for sunlight in the winter, I think the amount of UV light varies over the year and place, not to mention you rarely have a full day of bright sunlight in the winter. At least not over here.
 
carlsson said:
Maybe it has been mentioned before, but don't regular solariums emit UV light of the right wavelengths? If not, perhaps the lamps can be exchanged to ones that do, in case people already own half or full body solariums in their homes.

As for sunlight in the winter, I think the amount of UV light varies over the year and place, not to mention you rarely have a full day of bright sunlight in the winter. At least not over here.
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I'm sure solariums would have the right light. They are not common in homes here in NZ...we get more than enough UV! In fact solariums are regarded as a health hazard here.

We sometimes get bright sunny winter days in New Zealand. The blog entry about that was more for when it might be best for me.

I once spent 2 months in the UK during winter. I'm don't think I saw the sun once! :)

Tez
 
Tezza,

The sodium percarbonate will react with TAED to form peracetic acid and sodium carbonate, then will degrade further to produce peroxide molecules; it's essentially a peroxide donor and will make your H2O2 solution stronger. Peracetic acid is also a powerful bleach in it's own right.

If it's reacting, it's the right stuff, simple as.
 
Yellowing

Yellowing

It seems that we're all hell-bent on de-yellowing our troves.
But other, perhaps more respectable collecters, like coins, value the patina that has built up over the ages.
Furniture antiques are faked by stressing a reproduction so that it appeas the stresses have come from a life of hard wear.
No one trusty a shiny antique.
So what are we doing with removing the yellowig ?

patscc
 
patscc said:
It seems that we're all hell-bent on de-yellowing our troves....
.....
No one trusty a shiny antique.
So what are we doing with removing the yellowig ?
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Well, I guess that is a point of view. Some folk might prefer yellow cases. It might add charm or make the items appear like treasures of antiquity. For me though, as someone who wants to show off the collection one day, I'd like them to look as if they have just come out of the box.

I guess it depends on the individual. De-yellowing is certainly not compulsory. :)

Tez
 
On the contrary, I'm quite confident collectors prefer coins in shiny mint condition. While de-yellowing won't make a computer mint condition, it makes it look less ugly. Compare to paintings: many collectors prefer a professionally cleaned painting over one that is full of dust and cigarette smoke. Of course we shouldn't paint our vintage computers in the original colour, that would definitely make it worth less in the future. The question is whether this bleach process should be equalized to careful cleaning or crude painting?
 
Good question, Carlsson; I like to think of it as elegant Chemistry, deceptively simple in it's approach in that it looks easy to do, but if you were starting from scratch, would be really hard to figure out unless you understood it. It's restoring, so my view is it's the same as cleaning up a painting.

If your cleaned up item gets the "How the Hell...??" reaction from people, then that's what I was aiming for.
 
carlsson said:
On the contrary, I'm quite confident collectors prefer coins in shiny mint condition. While de-yellowing won't make a computer mint condition, it makes it look less ugly. Compare to paintings: many collectors prefer a professionally cleaned painting over one that is full of dust and cigarette smoke.
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I certainly feel this way about vintage computers I acquire. I won't even consider buying a computer if is all yellowed unless it is very rare and I think Merlin's de-yellowing procedure would work on it. Another deal-killer is a computer with "missing keys".
 
It's a personal preference. I like my old computers to have that 'lived-in' look, but I certainly wouldn't artificially distress a new-looking one just to make it look antique.

--T
 
carlsson said:
The question is whether this bleach process should be equalized to careful cleaning or crude painting?
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From my experience with it now, I would say the latter (careful cleaning). The cases don't appear bleached, or pitted in any way. The only difference is that they are back to the original colour. If it was cream/white originally, it turns cream/white. If it was light grey originally, it turns light grey.

You actually have to see it to believe it. It's quite astonishing really!

As I said in the blog, the procedure didn't "totally" de-yellow my RX-8800. More time and I'm sure it would have though. It certainly didn't damage the plastic, or even the brown "label" part, which I painted straight over.

If anyone is considering this and has doubts, I'd advise getting hold of a junk case and giving it a go (paint just half of it so you can compare). This is what I did, and it gave me the confidence to process the real units.

Tez
 
Druid6900 said:
Well, I wouldn't bleach a yellowed computer and then sell it, but, I would sell it and offer them the option, at an extra charge.
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Well, I've now done a couple of Osborne 1s, and I'm going to put one of them on EBay, to see what it'll fetch.
I'll note that it has been de-yellowed to look like it's original light grey and blue, through a non-destructive, non-abrasive chemical process. (I won't be mentioning anything about Urine Rescue).
 
Lorne said:
Well, I've now done a couple of Osborne 1s, and I'm going to put one of them on EBay, to see what it'll fetch.
I'll note that it has been de-yellowed to look like it's original light grey and blue, through a non-destructive, non-abrasive chemical process. (I won't be mentioning anything about Urine Rescue).
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I wouldn't mention de-yellowed, I would just say, refurbished, people don't need to know the hows, unless they ask.
 
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