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Removing Yellowing from Plastics - Part 3

@ cosam

The 133tne55 it has given us allows us to forgive a slight lack of investigative journalism; they don't let facts get in the way of a good story...

I am totally humbled by the fact we have achieved over 5 MILLION hits on Google, now that's something...........

@ Tezza

You should now have Organiser access to the Wiki mate.
 
Just for fun, here are some "soundbites" from sites and blogs that I posted on EAB after Googling Retr0bright...........

From The Null Device....

With the unabashedly 133t name of "Retr0brite" (or perhaps "Retr0bright".....) (You'd better believe it!!)

From Reddit....

I wonder if it works on Grandmas?
The yellow staining on your Grandmother has little to do with the existence of plastic, but more to do with the lack of it.
Good God! I love the Internet.
This is the exact line crossing moment for when concern for your old electronics turns into unvarnished geek obsession.


From Cracked.com....

Hah! Now I can pawn my old computers off as new!

From Gamesforum.ca.....

Think of it as "designer chemistry"

From Blog.makezine.com.....

Commodore restoration! I bow.

From Hackaday.com.....

I can’t tell you how eternally useful this will be, I’ve wanted to restore that snes for years, and no site has offered anything short of destroying the plastic..

This is like something off an Anarchy BBS from the 80’s. Or the scene in the motel in Terminator when they start making pipe bombs.


From Neogaf.com....

Haha.. Now they just need to make a TV-shop commercial for this.

From Racketboy.com.....

NON BELIEVERS, BEHOLD!!! (This was a quote from Eastside that did the SNES in The Gallery)
wow...Win !!

From Macresource.com....

It's a bunch of old computer nerds who just happen to be chemical engineers. I'm going to have the brightest Laserwriter on the block!

From rllmukforum.com.....

Yeah its cool that there's people out there who give enough of a shit to put the time and effort into researching a solution to a fairly trivial problem huh. Its class that it can be reversed.

:mrgreen:
 
Fantastic work! I really can't wait to try this out, I have a VIC-20 and an IBM 5152 printer lined up for the treatment :)
 
I have an old Commodore 64 "dirt brown" case I'm going to treat in the next few days. I'm going to do one half using the Xanthan Gum/glycerine (Loren's recipie) and the other using Arrowroot.

This time it will be exposure under a UV light, not the NZ sun

I'm sure both will give good results. Lorne has already done some comparitive work and I'd also like to get a feel for the pros and cons of both formulations.

Tez
 
Some white paint yellow like plastic. I don't know wich component of the paint do this yellowing.
 
@ fneck

Paint is a whole new world; the resins they use for some oil-based paints are notorious for yellowing. Linseed Oil is widely used for these types of paints and they are dried with manganese, cobalt and cerium-based driers (usually the carbonate salts). The problem with Linseed Oil based paints is that the oil is polyunsaturated and cross links as it dries to form a resin or varnish. It also means that there are spare carbon double bonds that can oxidise.

In short, I doubt it will have much effect on paint; you could try it though....

I think I really do need to get out more.....:mrgreen:
 
I've been wating to try this stuff for some time, so I went looking around of 30% peroxide, no luck.

So I went online, man this stuff is not cheap, 30% peroxide is easily $100 for 2 litres, plus you have to pay extra courier fees due to hazarous materials etc.

:eek:
 
I've been wating to try this stuff for some time, so I went looking around of 30% peroxide, no luck.

So I went online, man this stuff is not cheap, 30% peroxide is easily $100 for 2 litres, plus you have to pay extra courier fees due to hazarous materials etc.

:eek:

I guess it depends on how many cases you want to do. Bulk H2O2 is cheaper, but it doesn't need to be 30% to be useful. I've done all of my trials with 6% H2O2 bought over the counter, for use as a hair bleach. Weaker strength simply means you need to wait a bit longer to get the full-deyellowing.

That longer treatment time is offset by the safety factor. 6% H2O2 can be harmful if splashed in the eyes or (when activated) has contact with the skin for any length of time but it's a lot less hazardous that a more concentrate solution.

I've found for a typical case and keys, if you use a paste on the case and a soak with the keys, then you can get by easily with 1 litre 6% H2O2 with some to spare. I've recently found a cheaper supply of this at $8NZ per 500mls. That's $16 NZ ($8 US) per computer for the H202. The price of two good cups of coffee here. The price of other ingredients is negligible.

Tez
 
I have an old Commodore 64 "dirt brown" case I'm going to treat in the next few days. I'm going to do one half using the Xanthan Gum/glycerine (Loren's recipie) and the other using Arrowroot.

Just an update on this.

Well, things haven't gone quite as planned. Firstly, the UV blub I had arranged to get from someone else turned out to be infra-red, not UV (duh!). That being the case I looked for a florescent bulb (with holder) but this was going to come to well over $100. Given things are tight right now financially, I couldn't justify that.

Ok, so I fell back on the good old NZ sun. The good old UNRELIABLE NZ sun. Not too much UV gets through when the sky is covered with thick clouds and it's raining occasionally. Some de-yellowing has occured on the Commodore case but not a lot happened in the gloom of yesterday. I'm looking to buy a UV source off our local auction site, so I should have one in the next few days or so.

One of the purposes of this particular trial was to see for myself the difference between Xantan gum and Arrowroot in ease of paste production and effectiveness.

I used my own Arrowroot reciepe and Lorne's modified Xantan gum one.

I found both pastes to be easy enough to make up. I found timing in relation to blending is important with the gum, just as timing in relation to heating is important for the Arrowroot. I tried Lorne's 5 seconds for the Gum but found I actually needed longer to mix it. In the end though, it does form a good paintable paste, although less thick that the Arrowroot. I found with these trials that if the Arrowroot is too thick initially good vigourous stirring when the activators is added, indeed thins it to a nice paste.

With only 6% H2O2 I found almost no foaming at all when I added dissolved Oxy to the Gum Mixture.

There is a big difference between the two pastes as regards drying out. The Arrowroot dries out fast and "sets" on the case in large flakes (as Lorne also observed). The Gum/glycerine takes a lot longer to dry out and seems to remain sticky. Whether or not activity is occuring underneath the Arrowroot flakes is not known.

i'm supposing some activity must occur as my previous cases dried out in the same way after about 20-30 mins. I reapplied from time to time but the total time "wet" then was probably no more than 2-3 hours. This may have been enough to do the job under the strong UV levels in the sun (well over 100x stronger than most UV tubes) but I would doubt it.

Anyway, yesterday I reapplied both the Arrowroot and gum/glycerine paste every 3 hours or so. As I said, not much happened due to gloomy light and the odd shower. There was a slight de-yellowing though with no noticable difference between the two paste mixtures.

Today the sun is out and I've made one (and only one) application on the "only sightly-deyellowed" case. I'm not going to re-apply today. I want to see if there is any noticable effect in de-yellowing between the gum and the paste. I wasn't going to do this "drying" comparison today..I was looking for just a straight efectiveness comparison. However, I'm out of paste and Hydroxide to make it with. (I used a lot of my RX-8000 yesterday trying to get the final streks of yellow out of that too), so I just had enough for one more go with the C-64.

My hypothesis is that the Arrowroot paste needs more applications that the Gum/glycerine paste to be as effective under sunlight. If at the end of the day the Gum/glycerine case is considerably less yellow, it will support that hypothesis. If not, perhaps they BOTH need reapplication frequently when outside.

Tez
 
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So I went online, man this stuff is not cheap, 30% peroxide is easily $100 for 2 litres, plus you have to pay extra courier fees due to hazarous materials etc.

You're not in the US, so this link may not be directly useful. But these folks are selling 35% peroxide for $52/gallon including shipping. I bought a gallon and am playing with it and some old yellowed Atari stuff (pictures at some point, I promise). Regulations apparently prevent international shipment, though.

http://www.rebekahspureliving.com/peroxide.html

One of the nice things about the higher-concentration stuff is that you can mix the gel and Oxy with water alone, and add the peroxide as a last step. A 2:1 ratio gives about 12%, for example.

I find that doing this with an electric hand mixer works really well. Dissolve the Oxy first -- my brand (Oxi-Clean) tends to foam a little as it dissolves due to the fine powder, so let it sit for a while. Then toss in the xanthan gum and blend for a few seconds and you get a nice bubble-free gel. I didn't bother with the glycerine. Finally just before application, mix in the peroxide with a whisk. The liquid will diffuse through the gel just fine, with no worry about whether the oxy powder dissolves evenly. This also has the advantage of keeping the dangerous component in the garage, and away from pets and children.
 
I find that doing this with an electric hand mixer works really well.

Yes, I used a hand-mixer for my Xantan Gum/Glycerine paste this weekend.

If I was using high concs of H2O2 I probably wouldn't use a hand-blender as I'd be worried about splashes. I guess this would be less of a hazard if you are putting in the H2O2 last.

Tez
 
I've been wating to try this stuff for some time, so I went looking around of 30% peroxide, no luck.

So I went online, man this stuff is not cheap, 30% peroxide is easily $100 for 2 litres, plus you have to pay extra courier fees due to hazarous materials etc.

:eek:

In Canada, H2O2 over a certain concentration (IIRC the figure is 8%) is HIGHLY regulated to the point of paranoia.
 
Druid6900 said:
In Canada, H2O2 over a certain concentration (IIRC the figure is 8%) is HIGHLY regulated to the point of paranoia.

Which is weird since in the US you can buy D2O and U-238 among other interesting things. Oddly not even that expensive. I browsed the place that sells the aforementioned items but they oddly didn't carry H2O2 like I thought they would. How odd.
 
I'm trying the de-yellowing on my first Mac 512K parts. I'm not sure how they're supposed to look, as I've never had a Mac 512K before. Is the spacebar supposed to be a different color from the rest of the keys?

I own a Mac 128k that has been kept protected from UV light through the years so well that it is largely the stock beige color with virtually no yellowing. What this means is, unlike most Mac 512k and 128k keyboards you see on EBAY, my Mac's spacebar is the same color as all the other keys. That is the way it is supposed to be, and a discolored spacebar is a sign that the keyboard has been exposed to UV light.

After looking at your photos it appears that you soaked your poor spacebar for too long. It has turned platinum! The button side is the correct color. The original Macs were a light beige tone. Platinum tones didn't come until several years later, when the Mac SE and Plus Platinum arrived on the scene.

Question...

Do any of your chemical experts know if the addition of baking soda would accelerate the de-yellowing process or otherwise intensify the effect? You see baking soda and H202 everywhere now, and it's commonly recommended for whiter teeth. Obviously we are not into "whitening" here, but I am curious what kind of chemical reactions are going on with H202 mixed with baking soda (also mixed with Oxi).

Thanks.
 
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