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Removing Yellowing from Plastics - Part 4

falvesjr

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How long will it last?

How long will it last?

Hey guys,

I'd read about Retr0bright a few months ago and thought it was a great idea. Thanks to all involved in developing this!

Anyway, I'm coming to a point that I need to make a batch to de-yellow some C64 cases and some 1541 cases. I have skimmed this whole thread, but am left wondering about a few things...

- Do you find that, in principle, a liquid bath does a better/more even job than the gel?

- If I make a tub of H2O2 + Oxy + Water big enough for the parts I mentioned, how long will it last? Will I be able to do several cases, one after another in the same solution or will it stop working after X amount of plastic has been exposed or some amount of time?

- Should I add more Oxy over time?

- Does it make any difference if I use tap water or should I use distilled water?

- Has anyone found a good ratio of H2O2 (strength?) to Oxy to Water for larger batches?

Thanks for your thoughts and any guidance you can give me!

-F
 

Lorne

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@falvesjr:

Granted reading parts 1, 2 & 3 would be quite a chore, but the answers to your questions are contained in those parts.

- A liquid bath probably does a slightly better job than a paste/gel, but it is prohibitivly expensive, and a little more dangerous (it's tough to spill or splash a gel/paste).
- I've found that the H2O2 & Oxy mix will last about two days, and then it's spent.
- If you add enough Oxy the first time, you shouldn't need to do anything other than stir the stuff once in a while.
- No idea, I never diluted the 30% H2O2 that I was using.
 

Tupin

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Got a mixture going, used corn starch instead of xanthan or guar gum, I used most of the container to get it to a stage where the mixture is behaving like a non-Newtonian fluid, and put some on top of an ADB mouse. It is definitely bubbling, and I have a good feeling about this. :p
 

Lorne

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Got a mixture going, used corn starch instead of xanthan or guar gum, I used most of the container to get it to a stage where the mixture is behaving like a non-Newtonian fluid, and put some on top of an ADB mouse. It is definitely bubbling, and I have a good feeling about this. :p

You are aware that by using the RetroBrite process, you are required to take and post before and after photos, aren't you?
 

Tupin

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Took a before picture, I'll take an after picture if it turns out.

It's like all dried up at this point except for a few parts, I'm trying to keep it from turning rock hard by mixing it around a little.
 

Lorne

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Took a before picture, I'll take an after picture if it turns out.

It's like all dried up at this point except for a few parts, I'm trying to keep it from turning rock hard by mixing it around a little.

The paste or gel will dry out somewhat, and reapplication will be required, if the desired results haven't been achieved yet. That's completely normal.
You can also just grab a paint brush and mix what's already on the parts around a bit (and then maybe add some more). I would think you'll need the stuff on the parts for at least 6 hours using 12% H2O2. And if you're doing this outdoors, it will dry out much quicker. There are no hard and fast rules for this - you get the hang of what to do in what situation, after you've done it a few times.
 

Tupin

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I'm going to have to do this again, it did get something off, but it barely brightened it at all. I probably used too much corn starch, I forgot that it would dry up quickly when it set....

I'll post pictures of it when I get it right.
 

Merlin

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You are doing fine, Tupin; stick with it....kitchen chemistry rocks, doesn't it?

:D

@ falvesjr

1. Tap water is fine.
2. A bath of liquid is ideal, but the gel scores over the liquid for large areas.
3. If you make up 10-15% H2O2, you will be able to treat a few cases and a bath of liquid will last 2-3 days tops.
4. 10 to 15% is the "sweet spot" for the H2O2, where you get the quickest results without causing the white 'bloom' effect.
5. Adding more Oxy won't make that much difference; you may speed things up initially, but the liquid will be spent quicker. Slow is good with this process and let's face it, 2 days to remove 20 years of yellow isn't that long, is it?
6. The yellow colour is only a few microns thick, so the area that can be treated is huge, actually.

Does that answer your questions sufficiently?
 
Last edited:

tezza

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I'm going to have to do this again, it did get something off, but it barely brightened it at all. I probably used too much corn starch, I forgot that it would dry up quickly when it set....

I'll post pictures of it when I get it right.

Are you using the sun or a lamp? UV levels in the sun are much higher (at least where I live) and I've found de-yellowing is much faster than a lamp. You just have to be careful the mixture doesn't dry out.

I used arrowroot for my first units and that tended to dry out quickly too, like your corn starch. Reapplication works, but I've found Xanthan gum doesn't dry out so fast, even though it requires careful mixing initially.

Tez
 

Merlin

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Tezza

The difference is that Xanthan Gum skins over slightly and this slows the drying out down quite a lot. Corn Starch and Arrow Root don't have the same property.

No-one has tried it yet, however I believe that wallpaper paste may have similar properties to Xanthan Gum, but may be easier to disperse.
 

Tupin

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I might have to try this over Labor Day weekend in the sun, I have no practical UV lamp source that I could shine over the item being treated.

Glycerin, I can see why it's a needed part. I made and applied the mixture three hours ago and it still isn't dried out. I just coat the entire thing in the gel, but it was hard to do until it set up a bit.

Oh, and I forgot to mention that the last experiment I tried DID remove several brown splotches that were a product of yellowing, it's just not yellow itself.
 

Merlin

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Well, if it's any help, Lorne doesn't need a UV lamp but then again, he does live in Arizona, so lack of UV is not an issue!!

Keep us posted and we will help you until you get the swing of it.
 

falvesjr

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Thanks

Thanks

Lorne, Merlin,

Thanks for the replies! I guess I'll have to try one of the two methods soon and will let you know how it goes. And yes, I'll try to take pics! :D

-F
 

Tupin

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Well, I decided to go back to Retr0bright's early days and just let it soak in 12% peroxide. The mouse is simply just too curved and everything I put on it ran right off. It's not like an Amiga mouse, or even an original ADB mouse.

I'm still thinking I should put some Oxy in the mix, though, as I'm thinking it would take several days to change with just peroxide.
 

Lorne

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Well, I decided to go back to Retr0bright's early days and just let it soak in 12% peroxide. The mouse is simply just too curved and everything I put on it ran right off. It's not like an Amiga mouse, or even an original ADB mouse.

I'm still thinking I should put some Oxy in the mix, though, as I'm thinking it would take several days to change with just peroxide.

You need to go back and read parts 1, 2 and 3, and take notes.
The Oxy is what makes it work.
Put some Oxy in there (not too much), and give it a little stir, otherwise you're just wasting H2O2 (good thing you got the stuff cheap).
 

Merlin

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Yeah, I figured that out pretty soon, mixed in some oxy, and it's been bubbling for hours.

Good; that means the TAED is breaking down the peroxide. Now all you need is enough UV light to vibrate and break off the oxygen atoms from the bromine atoms in the flame retardant.
 
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Tupin

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Bad time for that, it's an overcast and rainy day.

Would putting it directly under a normal lightbulb work?
 
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