Removing Yellowing using H2O2, TAED & UV

[alexh]

It is just over a year since the widespread news that you could reverse the yellowing of Amiga (and other retro computer) keys using a mixture of high concentration H2O2, TAED (Oxy cleaner) and UV light.

I was wondering if anyone had any tips, techniques for a first timer?

What is the best concentration of H2O2 to use?
How much TAED to use?
How long to leave them in there?
Do the keys float? If so do they need to be weighed down?
How long to rinse them for afterwards?
Any possible side effects?

I want to perform this on my A500+ keyboard as a test because it is easy to get replacements, then my new Amstrad CPC6128 Plus if the results are successful as it's keys will be almost impossible to get replacements for if I screw up.

Obviously safety is my primary concern and I have got some safety specs, gloves, a metal tripod for holding the UV bulb.

[Zetr0]

@Alexh

where the hell have you been?!

Retr0 Bright Wiki (includes gallery and recipes)*
Where it came to be
Retro-Bright Support

some times I wonder if you live under a rock my friend!


*this got slash dott'ed a while back.... you must be the only netizen that DOESNT know...

[alexh]

Originally Posted by Zetr0

where the hell have you been?!

What do you mean? Re-read the first 6 words of my post!

My post is for practical advice from EAB members who have actually performed this technique.

The Retrobrite site is good, I had read it, but I'm not to sure about the paste idea for keys.

[Zetr0]

with the Gel version there should be a HUGE warning label..

DO NOT ALLOW TO DRY OUT!!!

if you do the concentration H2O2 will increase running the risk of it getting to high and it will beging to destroy the polymer bonds. best thing to advise is to reapply avery 45 - 60 minutes

[8bitbubsy]

This is a thread for Merlin *Waiting for him to appear from the vague mist*

[rkauer]

Originally Posted by alexh

It is just over a year since the widespread news that you could reverse the yellowing of Amiga (and other retro computer) keys using a mixture of high concentration H2O2, TAED (Oxy cleaner) and UV light.

I was wondering if anyone had any tips, techniques for a first timer?

What is the best concentration of H2O2 to use?

9 to 12% is the best. Not too much strong, which can cause blooming effect on organic pigments (used in the A500 and other beige plastic)

How much TAED to use?

Only a tea spoon pre-diluted in hot water. Nothing more.

How long to leave them in there?

Pending on the yellowing and if you will expose the jar (liquid solution) to direct sunlight or to an UV bulb. Speed is not a desired feature, the more time the process takes (read: slow reaction), better the results as you will have control over it.

Do the keys float? If so do they need to be weighed down?

Simple answer: put the small parts in a glass jar, they will not float.

How long to rinse them for afterwards?

Just enough to not smell the H2O2 any more.

Any possible side effects?

Besides the blooming effect if you use a too strong solution, just the fact that after treatment the pieces will start yellowing again after some months. Use some varnish/lacquer matching the treated surface to insulate it from air.

I want to perform this on my A500+ keyboard as a test because it is easy to get replacements, then my new Amstrad CPC6128 Plus if the results are successful as it's keys will be almost impossible to get replacements for if I screw up.

Obviously safety is my primary concern and I have got some safety specs, gloves, a metal tripod for holding the UV bulb.

Good luck!

[Merlin]

Shazam!! Merlin appears.....

Alex, here are afew helpful hints.

1. If you have a dishwasher, put the parts in on a cool cycle first. This will ensure that they are clean and the surface is better prepared.

2. Keep the H2O2 between 10 to 15%, this is the ideal mix that gets the quickets results without attacking the ABS polymer.

3. If you are making the gel version, cover the parts with cling film after applying the gel. This reduces or stops evaporation and the effect that Zetr0 warns about.

4. Check on the parts every couple of hours. I wouldn't go more than 2 hours without checking the parts.

5. Heat is bad. Keep the UV at least 12" away from the parts or you risk heating them up and causing distortion, particularly on long or thin parts.

6. Above all, have patience; these parts have taken at least 10 years to yellow; a few hours extra to remove it won't hurt. Rkauer is spot on with his comments.

7. Protect yourself; wear rubber gloves and safety glasses. These are dirt cheap from DIY shops and you don't get another pair of eyes. 10% H2O2 will sting like a mofo if it gets into cuts in the skin. If you get a splash on your skin, rinse it under the tap for 10 minutes to ensure it's removed.

8. Blu-Tak or plastercine is ideal for weighting keys down so that they don't float.

9. If you use a jar, DON'T screw the lid on tightly!! This process evolves gas (oxygen) and pressure will build up and possibly burst a jar or bottle. If you need to use a jar, pierce a hole in the lid to allow gas to escape.

10. Once the reaction has finished, the solution can be safely disposed of down the drain, as the H2O2 will ahve decomposed to water; TAED is biodegradable so there's no risk to the environment.

If you have any other questions, please ask.

[alexh]

Originally Posted by rkauer

after treatment the pieces will start yellowing again after some months.

That quickly?

Originally Posted by rkauer

Use some varnish/lacquer matching the treated surface to insulate it from air.

Anyone got any experience of this?? The type to use?? The last thing I want is for my keys to look like they were painted with a clear coat.

[alexh]

Originally Posted by Merlin

If you are making the gel version, cover the parts with cling film after applying the gel.

Is there any advantage over the liquid solution?

Originally Posted by Merlin

Blu-Tak or plastercine is ideal for weighting keys down so that they don't float.

I was thinking something similar but I was not sure if it would react with the solution.

[Merlin]

@ Alex

If you clear coat the parts with an acrylic lacquer once they are restored, they won't go yellow again, as oxygen cant get to the surface. What rkauer means is that the case may eventually start to discolour again, but this could take years. A good UV protective car polish like Turtle Wax, Armor-All or Autoglym could also be used to seal the surface.

The gel is only of benefit if you are treating large parts, such as a monitor, printer, etc. where a large bath of solution would be expensive. The gel is also handy if you don't have a large enough container for, say, an A1200 case.

The solution doesn't react with Blu-Tak or plastercine. Tonyyeb proved that very early on in our tests.

Also, don't go mad with the quantity of Oxy; TAED isn't soluble above 1.5 grammes per litre and adding a lot of Oxy will create foaming. I would suggest 1/2 teaspoonful per 5 litres of liquid as a start. You can always add more, but if it's foaming all over the place, you can't take it out!!

Next!!

[amiman99]

Hi, Recently, I have de-yellowed few Amiga and Atari cases with "Clairol Professional" Pure White 30. You can buy it in USA in beauty supplies. No need to mix any other chemicals, you also need a good paint brush.

My Atari ST was brown not gray and I was able to turn it gray again.

The A500 was yellowed also and it looks like new again - the Commodore logo was peeling abit.

The A1200 case was yellow also and I was able to turn it white again. No damage to the logo on top, but the serial number on the bottom was washed out.

The trick is: Apply thick coat of the "Clairol" and leave it in the sun for 30min, then reapply another coat every 30min until discoloration is gone, it took me from 10AM to 6PM in one weekend. The temp outside was about 80-90deg F, high humidity.

When done, wash it in water and allow to dry.

My next project is C64C, the newer model, its quite yellow now.

I hope it helps.

[Merlin]

@ Amiman99

Good stuff! One thing to watch though; Lorne over at VCF found a peroxide cream hair treatment and he found that it attacked the surface of some plastic parts. We took the formula apart based on what was on the label and MSDS sheet (yes, really!) and we found that it contained a terpene solvent that was attacking the plastic surface.

It's always useful to test this sort of stuff on some scrap parts first if you are unsure.

Oh, and we want before and after photos; we loves our hardware pr0n, we does.....

[amiman99]

@ Merlin

I got the "Clairol", because they did not have pure 30% peroxide (I wonder if 40% would be better) also I forgot to buy the Oxyclean. I read on some threads that some people wanted to make a thicker solution, so I said, why not, lets try it. I had a spare yellow A1200 case I could try it on (just got it from EBAY for a Slim CDROM mod). The rest is history.
I'll post some pics of C64C, when the weather clears up, I'll do it.

I still have brown Atari ST bottom part of the case, I'll do that one too. The difference is amazing.

---I just read that more % peroxide would not be better

[Merlin]

Correct; stick to between 10 to 15% or you risk attacking the polymer.

[TjLaZer]

I also used the Clairol Pro 40 Creme developer and it works great.

[mully]

Anyone know where I can get Hydrogen Peroxide 10 to 15% strength in Australia? Hair suppliers, chemists and Google searches here only have much lower strength.

Are keyboards (A1200) best Retrobrite'd intact, or should the individual keys be removed? Removing keys looks tricky but if treating intact won't the liquid/gel harm the underneath circuits?

Thanks.

[Zetr0]

@mulligans flat

the keyboard consists of several parts

• plastic film membrane
  plastic keyboard matrix
  plastic Keys
  metal backing plate
  metal springs

If you remove the backing plate, you can then remove the plastic film membrane you could leave the rest of the assembly as a whole (without removing keys) if you so desired.

However you may have difficulty geting the process to work effectively using say the GEL application between the keys. You may end up at the end of the process with a non-uniform result.

its a case of try it and see =)

you can use lower concentrations of H2O2 peroxide, it will just take a bit longer.... rememeber to wash your plastics first.... preferably in a dish washer at 50c or 60c (dont do this with thin / long plastics as they are likely to warp)

If you were using just a the liquid solution, then anything around or under 8% could take a 3 to 5 days (or even a week) to obtain the results.

with the GEL version I honestly dont know at those low-concentration levels... it would certainly take many applications of it... most likely over a series of days.

being stuck in that situation, (only able to get 6-8% H202) I would apply 6 coats of gel over 6 hours, at the end I would rinse and repeat this the next day....

after a good three days you will notice that this method is working or not.

[alexh]

I'm going to remove all my keys, blu-tac them to the bottom of a small washing up bowl and add a solution of H2O2 + TAED with the UV lamp about 12" above.

Should I do all of them at once? To try and get the same colour level on all of them? Is it a problem to get an even colour if you don't?

[Zetr0]

Originally Posted by alexh

I'm going to remove all my keys, blu-tac them to the bottom of a small washing up bowl and add a solution of H2O2 + TAED with the UV lamp about 12" above.

Awsome! thats the way i'd do it.... caution though, that the bubbling of the H202 can *Rise* keys from the bottom of the bowl, even with blu-tac

heat will drastically alter the time of the reaction, so keep it room temperature (18c)

remember to photo-document your work, at best it becomes yet another shinging example, and at worse a good antithesis of the process to improve it further.

Originally Posted by alexh

Should I do all of them at once? To try and get the same colour level on all of them? Is it a problem to get an even colour if you don't?

Now, TECHNICALLY, as we are using a low concentration of H2O2, it *should not* have the concentration to over-do the plastic. once the optimun de-protination has complete it *should* stop reacting.

This is the prime reasons for using low-concentrations of H202, so what does this mean, well depending on your solution there exists an optimum time for the process to work full... a large window of time where the job is complete and if you leave it too long it may well start reacting with other polymer base compounds (this would take a while).

you cold do them all at once, (if you have the space / solution) or simply in batches using the same solution concentration and time, everything *should* be fine =D

*Over baking/cooking of the plastic, where by the H2O2 begins to attack the base organic compunds of the polymer is normaly only seen when the concentration of the H2O2 is either to high or its concentration rises during the process (i.e. heat / evaporation)

[Merlin]

@ Alexh

That's exactly how Chris (Tonyyeb) treated his keys and it worked out just fine.