Removing yellowing from Amigas with peroxide

[Merlin]

OK Guys, here's some intersting info, I came across this as I read up about a dust explosion on the HSE's web site (I'm a safety manager by trade) and it threw up the fact that the company concerned made a chemical called TAED, which is the active ingredient in the "oxy action" products, see below. I found this in the Wiki for TAED.

TAED is an important component of detergents and bleaches. Its is an activator for "active oxygen" bleaching agents. Such active oxygen bleaching agents release hydrogen peroxide during the wash cycle. Such agents include sodium perborate, sodium percarbonate, sodium perphosphate, sodium persulphate, and urea peroxide. The released hydrogen peroxide is an inefficient bleach below 40 °C, except in the presence of activators such as TAED.

The activation process entails a reaction of the hydrogen peroxide with TAED to release peracetic acid, which is a fast-acting beaching agent.:[1]

(CH3C(O))2NCH2CH2N(C(O)CH3)2 + H2O2 → (CH3C(O))2NCH2CH2NH(C(O)CH3) + CH3CO3H

Now, guess who has some 35% H2O2, is calling at Maplin's on his way home to buy a UV bulb, and is going to test the 35% stuff with some Vanish Oxy Action added to it? Stay tuned.....

Science Abuse Rules !!!!

[Zetr0]

Zetr0: Temps the idea of adding a webcam to this project at merlins house

You know my friend, if you end up in my back garden smoldering yet looking fresh and white, I believe we can constitute that maybe that was "too much" Oxy Vanish

still while your over we can have barbeque's

[Yoto]

I´m already imagining it....

" But i was only trying to bleach my Amiga!"
"Yeah right...! Save it for the judge!"

[Merlin]

*ahem*

Apart from being a Safety Manager for nearly three years, I was also an Industrial Chemist for 25 years before that, I think I know what I am doing.....safety always comes first.

[Magno Boots]

I've tried the oxy and peroxide mix previously.

You should see a massive amount of foaming at first until it dies down. It will stabilise but will still release many bubbles (like cola in a bottle).
Mind you, I did add a full scoop to the liquid.

I didn't leave it long enough to find if the mixture actually worked well.

Keep us posted.

[Merlin]

@ Magno Boots

Was that with or without UV light? The UV is another magic ingredient it seems.

Overall, the best conditions for success seem to be:-

1. Hydrogen Peroxide, higher strength the better;
2. TAED (Tetra Acetyl Ethylene Diamine), the ingredient in the "oxy cleaners" to catalyse the reaction below 40 degrees C;
3. UV light over an extended period (or lots of it in a short burst )

I have a very yellowed A500 that I collected from DuneInfo; I intend to use some of the uber yellowed keys for my testing and I will take before, during and after pictures so that we can work out the optimum conditions for a quick result.

Thanks for the tip about the foaming, I will start with small volumes of peroxide and "Oxy" so that I don't spill it all over the place.

Hmm... we carry acetylation reactions at work when we make polymers, I wonder if I can synthesise neat TAED with Ethylene Diamine and Acetic Anhydride or similar, and what catalyst might I use.......I feel some research coming on......

[Zetr0]

"hmmm.... might need to fill out that warrenty card on that UV bulb my friend"



In all truth I am VERY excited, I m looking forward to seeing how well this works and how often the solution can be re-used before exhaustion

@Magno

my friend, what was the H2O2 concentration in your solution?

[laser]

Originally Posted by Yotoxionomai

@zipper
Bleach is good to eat thru organic material, and its corrosive so i guess it could speed up the yellowing process, having the opposite result! ( But a test surely wont hurt)

See also:
http://www.vintagecomputing.com/index.php/archives/189

nice SNES article but the author can't find the solution at the time the article was done
he recommends pinture

btw,


I have yellowed plastics from computers and other things here that never were exposed to the sun, or to the UV light but are now yellowed

my conclusions:

UV light = myth

some heat can accelerate the process I think ...cause anybody can check that on any old CRT monitor were the site of the plastic was exposed to the heat is notably more yellowed than the others plastic' sites never exposed to the heat

also

bad plastic= yellowed in a short time...it doesn't care if UV light or heat
good plastic = never yellowed or yellowed in a long time

btw, my commodore 64 C is white like new....and it's 20 years old but my datassette also 20 years old is ugly yellowed

so...what kind of heat or UV light can affect my datassette but not my commodore 64?

pics soon

[Zetr0]

@laser

you did actually read that article that was posted or guess from the pictures?

depending on the mix of flame retardant chemicals added to the plastic will determine how quick the plastic takes for these chemicals to react to heat & UV.

now remember UV is everwhere, you dont need direct sun light, infact florescent lighting is perhaps worse than direct sun light.

Heat on the other hand is a catalyst for pretty much every reaction in the known universe so i can see some scientists perhaps crying over your statements.

also as a note to this, when mixing plastics and chemicals together, its pretty much like porridge or rice pudding, its never 100% even throughout the batch, thus why you can have a pristine condition plastic from the same batch of one that has more of an orange tan than julio iglesias.

[Yoto]

@laser
Thak you laser for your input, but i posted that link because the autor claims to have tested bleach and it seemed to have contributed somehow to yellow the plastic in a different way.
As long for the paint process i recall you posted it as a option too some time ago, cant remember the thread thou...
Anyway if you read the comments below in that same link i posted you will see some people advising the autor to use peroxide too.

[Merlin]

@ all

OK, lets disassemble some of these sweeping statements with a Chemistry hat on....

UV Light = myth
Sorry, that's bollox. If that were so, why would double glazing be made with uncatalysted PVC? They make it that way because the UV affects the catalyst and causes yellowing. In fact, the PVC probably has a quantity of a UV absorber added, which will translate the UV to another wavelength via a Stokes shift of wavelength to another frequency, to reduce the effect of the UV light.

Bleach is good for removing yellowing.
Hmmm, doubtful. Since the bleach will contain Chlorine, this will attach to any antioxidants (free radical scavengers actually) in the plastic.

Bad plastic yellows over time irrespective of daylight.
This has some truth in it; since the plastic is heated as part of the masterbatching process before it is moulded or extruded, the amount of anti-oxidants added and the moulding temperature can have a pronounced effect on the long-term stability of the plastic.

For those who don't know, the term "plastic" means flexible or mouldable; to achieve this, the plastics formulators start with something like Styrene or Acetal Butyl Styrene (ABS) and then add plasticisers, an example of which could be di-iso-octyl phthalate (DIOP). DIOP is a liquid which, when added to the plastic and moulded, flows between the interstices of the polymer chains and imparts a 'lubricating' action between the cross linked polymer chains, allowing the material to become flexible to a degree. Plastic isn't a true solid, it just looks it to the naked eye; if you were to zoom in to a molecular level, you would see a lattice of cross-linked chains of polymer, with particles of colour, antioxidants and plasticisers in between.

The thing to rememeber though, is that although polymer manufacturers strive to cap the polymer chains and make the molecules fully saturated and cross linked, that doesn't happen 100%, so that the amount of free unsaturated bonds in the plastic can absorb oxygen and oxidise the material, causing yellowing.

Adding peroxides and catalysts such as TAED introduces more free radicals in solution as H+ ions, which can preferentially remove the oxygen atoms from the degraded plastic, reversing the yellowing. Once treated, there is always the risk of degradation returning, so I would advise treating the surface with an acrylic lacquer to seal it, acrylics being more resistant to yellowing than some other types.

Right then, drum roll please........

The Kitchen Science Abuse Series: No.1: Reversing Yellowing of Plastics
THE PROCESS WORKS!!!!

The patient: an old Naksha mouse house, I thought I'd risk that first.

The process conditions: 35% H2O2, room temperature, 75W UV bulb, 1/2 teaspoonful Oxy to approx 1 litre of peroxide solution, 2 hours exposure.

See the photos attached, the yellowing is reduced by over 75%, I reckon 24 hours would have it back to as new.

The solution frothed up badly and overflowed the half plastic lemonade bottle container I used for testing, it was a good job I'd placed this and the bulb inside a large jam making pan as a precaution. I need to cut back on the Oxy to a smaller amount which I will work out over the next few days. If you have a weaker peroxide solution, it may not froth so badly but may take longer, however, the process can be accelerated and UV definitely helps.

[Kristian95]

@Merlin:

Nice result But not much more impressive than what rkauer achieved with 35% H2O2 alone Ok he had to leave it for 72 hours but it all got nicely whitened (Amiga keyboard).

Thus I think it is safe to say that UV and/or Oxy catalyze the process but that H2O2 alone can do the trick just fine

Btw, no frothing with H2O2 only

[Merlin]

Yeah, I know, it's the detergent in the Oxy that causes the foam, I may try and synthesise some TAED at work this week.

[rkauer]

Pure H2O2 causes foam, too. But in a much lower grade.

TAED is good, since it helps the reaction (I'm a plastic engineer, too!).

BrOP flame retardants is the problem, here. It migrate to the surface of the plastic, opening a "channel" for more oxygen reaching the polymer chain, brittling the plastic and giving it that "Julio Iglesias" (argh!) look.

The "natural" process is not perfect, since it don't have controlled parameters. Four entire days for the keys and they still are yellowed (slightly, now).

Merlin's approach is near the perfection, here. Control parameters are always cool.

@Merlin: perfect explanation, m8. I couldn't made it better!

[Merlin]

Thanks Rogerio, not bad for a chemist from the oil industry who has worked in plastics pigments for three years, eh?

I always take the time to understand how these processes work. If I can understand it, then I can explain it.

Watch the sales of peroxide, fish tanks and UV lamps go up now, I should buy shares....

[Yoto]

Great post Merlin that really satisfied my curiosity!Thank you man!

[laser]

Originally Posted by Zetr0

@laser

you did actually read that article that was posted or guess from the pictures?

depending on the mix of flame retardant chemicals added to the plastic will determine how quick the plastic takes for these chemicals to react to heat & UV.

now remember UV is everwhere, you dont need direct sun light, infact florescent lighting is perhaps worse than direct sun light.

Heat on the other hand is a catalyst for pretty much every reaction in the known universe so i can see some scientists perhaps crying over your statements.

also as a note to this, when mixing plastics and chemicals together, its pretty much like porridge or rice pudding, its never 100% even throughout the batch, thus why you can have a pristine condition plastic from the same batch of one that has more of an orange tan than julio iglesias.

yes..Zetro but I haven't fluorescent lamps where I used my C64...in my house there are fluorescent lamps only in the bathroom

check my pic

my C64c is almost white...while the datassette is a bit yellowed..and the PSU is ultra yellowed.....
I can understand that heat can affect the PSU because is warm when is in use...but UV light ?
all these articles are 20 years old and used under idem conditions
I don't know where the UV light can affect this entire case
also UV light not affected the SNES console in the article.....the console was yellowed inside & outside....but inside the console is always in the dark

btw, we must create a gel or a cream based on h202 to be used on that plastics that can't be submerged into h202....examples:big parts of plastics...or plastics than can't be dismantled

any ideas?

[rkauer]

Originally Posted by Merlin

Thanks Rogerio, not bad for a chemist from the oil industry who has worked in plastics pigments for three years, eh?

I always take the time to understand how these processes work. If I can understand it, then I can explain it.

Watch the sales of peroxide, fish tanks and UV lamps go up now, I should buy shares....

Yeah, not bad at all!

I use to have my own plastic plant (as a converter). I made PE films, bags and that sort of things on that era. Don't ask why no more, all I can say it was caused by a family problem... sigh...

Also had a Brazilian patent for a special type of shopping bag, myself. It have a strip on the upper and through one side to "zip" it (useful for people who like to go to beach). I think the patent is no more valid, since the fabric is closed for a couple of years, now...

[Magno Boots]

I'm really enjoying this thread as it relates to something that every Amiga owner needs to know.

I've now had my 1200 keys in a jar of 9% peroxide for three days and have noticed a slight difference but nothing compared to my a600 attempt.

I believe that Merlin has a valid point regarding the vanish oxy as my 600 keys had been previously soaked in this (see post two in this thread) with good results, then popped in peroxide only, resulting in pearly whites.

I think the oxy starts some reaction off initially and the peroxide can finish the job off completely.

Please keep posting your findings

[Zetr0]

!!!AWESOME!!!