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Removing Yellowing from Plastics - Part 3

lumpydog

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Well done lumpy. Certainly my 6% works well enough given enough UV. Good to know the indications are you can go even lower. Did the increased oxy concentration help with very low concentrations of H2O2 I wonder?

Did you find the immersion technique expensive? Over the counter stuff has a significant markup?

Tez



Tez:

I'm not sure about the increase in the Oxi-Clean helping to offset. It works though! The over the counter stuff is about $2 per litre. I've spent about $30-40 on the stuff, but it's worth it to me... I've cleaned 2 Macs + Peripherals and 2 HD20 cases.

Lumpy
 

Lorne

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@ Lumpy

As Lorne freely admits, has has a patience problem; he basically wants it finished during the commercial break..... :mrgreen:

:lol:

Preferably during half of the commercial break, so I can do other things in the remaining time.


@Lumpy:
Yes Merlin is correct: the MSDS on my stuff says not less than 30% and not more than 40% hydrogen peroxide. I'ts a carpet cleaning product named Urine Rescue that is manufactured by ProChem. They have a few branches across the US, and distribtors all over, that sell it for about $ 21 for a one gal jug.
I might try the liquid solution again, and immerse a whole case in the liquid, but dilute it considerably from the 30-40%. I seemed to get more even (no blotchiness) results surrounding the part in the liquid. I have found Apple plastics to be a pain in the butt - they don't seem to want to de-yellow evenly. They are, so far, the only manufacturers plastic that I have seen come out this blotchy.


And yeah guys - the response is wild.
Unbelievable !
Well done.
 

tezza

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I have found Apple plastics to be a pain in the butt - they don't seem to want to de-yellow evenly. They are, so far, the only manufacturers plastic that I have seen come out this blotchy.

I've only treated one Apple. The IIe Platinum. The case came out very even indeed, even with the quickdrying Arrowroot paste. It looks beautiful. I can't say the same for some of the keys though, which were soaked. Some of the larger ones did come out blotchy (or streaky).

My Platinum was made in Singapore. I could be wrong, but I suspect it's not so much an Apple problem but more a "local plastics" problem. Many of these computers were manufactured in plants all over the world and the plastic used probably varied from plant to plant.

Tez
 

Terry Yager

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It's gone mental - everything from consoles to Lego, from Land Rovers to Alfa Romeos, old telephones, fruit machines, the list goes on; it's absolutely EPIC!!


We iz teh L33tne55!!!

See, I just knew there would be a market way beyond a handful of nut-job vintage computer collectors. You coulda been rich!

--T
 

Terry Yager

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@ Terry Yager

This is what I mean by a hand blender or stick blender :-

5g-big.jpg

OK, yep...that's definitely a hand blender, even in Americanese.
This is what I mean by a liquidiser:-

31V8JGWSZDL._SL500_AA280_.jpg

And this device we call a blender. I don't own a mixer, so I can't show a pic.

--T
 

KyPinGuy

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See, I just knew there would be a market way beyond a handful of nut-job vintage computer collectors. You coulda been rich!

--T

It's entering the pinball restoration hobby now - we have TONS of yellowed plastics in our machines that we want to restore. A lot of our plastic is PET instead of ABS - any chance that anyone has testing on non-ABS plastics? I would assume the flame retardant exists in most plastics, especially those near electrical equipment. Also - has anyone tried this on clear plastic?

I'm going to try and experiment with some parts over the next week or so. I'll respond back here, in case anyone is interested.
 

Merlin

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@KyPinGuy

I have some fruit machine reel tapes coming my way for testing, I'll post the results here.

PET (Poly Ethylene Terephthalate) is normally used for clear applications (like the large plastic lemonade and cola bottles) and the flame retardants used in these aren't usually bromine based as the colour can be a problem. For PET I would have expected them to go for something like phosphorus based retardants or chemicals such as potassium perfluorobutane sulphonate, which impart flame retardant properties but still allow for the plastic to remain crystal clear. I reckon the same will apply to Polycarbonate and HIPS (High Impact Polystyrene) which was used for later computer keyboards.

By all means give it a try and report back, but I am doubtful if it will work. Retr0bright was developed specifically to target the brominated retardants used in ABS in the 80s and 90s; plastics technology has moved on a lot since then.
 

Lorne

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Lorne mate,

There are some interesting comments about the transparency of the gel; I noted that when I was using Kelzan D Xanthan Gum, I always got a near crystal clear gel.

I just receievd my free sample (9 oz) of the Kelzan Xanthan Gum. I'm looking forward to trying that stuff. I had to tell them what the application was when I asked for the sample (rather than purchase the 50 lb bag it comes in), so I sent them a link to the Wiki.
They sent it out, and I got it in two days. They must like the application, and see the potential (in future sales).
 

tezza

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I just receievd my free sample (9 oz) of the Kelzan Xanthan Gum. I'm looking forward to trying that stuff. I had to tell them what the application was when I asked for the sample (rather than purchase the 50 lb bag it comes in), so I sent them a link to the Wiki.
They sent it out, and I got it in two days. They must like the application, and see the potential (in future sales).

Does the opaqueness differ between different Xanthan Gum manufacturers? When I get home I'l have to see just what Xanthan Gum I used on the Commodore case. It made up to a very clear gel, at least when it was on the case anyway.

Tez
 

Lorne

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Does the opaqueness differ between different Xanthan Gum manufacturers?
Tez

I haven't tried this new stuff yet, but the other XG I used was a food grade XG, and it was light brown/beige in color. This Kelzan (an industrial use XG) is white. Merlin said it was almost clear after he mixed it, which should mean for more UV getting through to the plastic.



Update: be careful on the de-yellowing/de-browning of patio furniture if it isn't made of only plastic. I tried de-yellowing some patio furniture that used a plastic/fabric web for the seating area, and while it de-yellowed it, I found that after pressure washing it, the fabric is now only threads (instead of a weave of threads). It could have been the H2O2 mixture, the sunlight degrading the mesh, the pressure washing , or a combination of the three. Who knows? If I'd hosed it off instead of pressure washing it, they'd all be OK now. Three of the four chairs look better anyway.
 

Merlin

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@ Lorne

You may find that the colour difference is down to the fineness of the grind of the powder; it tends to get whiter the finer you grind it (a bit like flour).

I used Kelzan D just because that's what I found in the lab at the factory where I work and that was the only xanthan gum they had. There are a range of Kelzan xanthan gums but they are all fairly generic. Some are coated to aid dispersion.

The glycerine will also make a significant difference to the clarity of the gel.
 
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tezza

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I haven't tried this new stuff yet, but the other XG I used was a food grade XG, and it was light brown/beige in color. This Kelzan (an industrial use XG) is white. Merlin said it was almost clear after he mixed it, which should mean for more UV getting through to the plastic.

Right. Yes, mine was a light brown colour. It still lead to quite a clear mixture though.

Tez
 

Merlin

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Hmmm, that could be the solvents at work again; it's hard to tell really.

I've got a sample of Kelzan on order from CP Kelco myself.

:)
 

AndyR71

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Hmmm, that could be the solvents at work again; it's hard to tell really.

I think it's more likely to be a purity thing. I'm using a gum from a local supermarket produced as a cooking ingredient (a gluten substitute) by Bob's Red Mill. As xanthan gum is a product of an edible bacteria, their powder is likely to be a fairly coarse mix of whatever was in the culture when it was dried. For this application (you don't use very much when baking) there's really no need to get a pure extract.
 

Merlin

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@ AndyR71

I don't understand your reply.

My comment about solvents was to Lorne, about his experience of plastic fibres becoming brittle in a garden chair after treating them with a peroxide mixture from a hair bleach product containing terpenes.

Regarding xanthan gum; I don't think that the colour of the dried powdered gum makes any difference at all really. By the way, xanthan gum is a gluten substitute.....
 

Unknown_K

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Don't get too crazy with the UV lamps because that is what caused the yellowing in the first place. I think direct sunlight is probably better then a UV lamp because not only does the UV rays decompose the Hydrogen Peroxide, but the heat from the sun will also raise the temperature of the parts which also helps decomposition. Hydrogen Peroxide decomposes from vibration, heat, and UV rays. Also metals will speed the process up quite a bit (toss some stainless steel in the tank maybe)?

What somebody needs to figure out is how fast the process can go before you are just bubbling away the Oxygen faster then it can stay in solution and react with the plastic you are trying to clean. I think adding that gum to thicken the solution probably just keeps the oxygen from bubbling out too fast as well as keeping it in contact with the plastic.
 

Merlin

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@ Vlad

245nm is short wavelength UV and is the wrong sort for what we need; we need UV in the 300 to 350 region, almost into infra-red. Also, if I thought we needed a bazillion watts of UV I would have said so, by using loads you are also risking degrading the polymer.

This is all about the minimum required to achieve the result, not about going high wide and handsome to prove how much resource you can throw at the problem. If I can do the C64 with 11 Watts of energy saving UV light (about 60 Watts in old money) in eight hours, why do you need more?

@ Unknown_K

We are using TAED in the Oxy as the catalyst, therefore further catalysts aren't required. You are correct in that the gel will slow down gas release and prolong the effect. UV and TAED together degrade H2O2 very quickly, as other on here have found.

TAED isn't soluble in water above 1.5 grammes per litre, more than that is a waste as it won't get used, so we don't need much Oxy at all really.
 

Mac128

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It's gone mental - everything from consoles to Lego, from Land Rovers to Alfa Romeos, old telephones, fruit machines, the list goes on; it's absolutely EPIC!!
I never understood why you didn't feel like the formula could be patented. Clearly, there is a commercial application for the product, which needs only some backers to help develop the formula so that it can be applied safely by even the most inept among us and it could be then marketed to increase awareness and sales. Indeed I am not aware of any product available for such an application. Even without a patent, there still seems to be potential to be the first company to package and market the product. Clearly the variation of plastics out there require different formulations to cover most practical applications.

Having said that, thanks for the generosity. And to everyone across numerous forums who have bravely sacrificed some of their old plastics during initial trials, so that I may have the safest, guaranteed path to success.
 

Yzzerdd

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Regarding patenting, I always thought maybe it was because from the start the formula was pretty well out in the open--open source. Can you patent open source stuff? I'm pretty sure you cant, but dont get me wrong, I dont know what I am talking about. I cant see someone trying to patent something open source, like an OS or anything if it's code was open from the start. How could they prove they had come up with it in the first place, right?

--Ryan
 
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