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Removing yellowing from plastics - Part 2

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It was a baiting post, not a typo; I have been waiting for you to take me on with the science part.......:mrgreen:

:lol:
 
Just to show how much of an anorak I have become about this topic....

Have you ever seen black bumpers (fenders) on cars, that gradually turn grey then white under sunlight? Well, that's because the bumpers are made of...yes, you've guessed it.... ABS.

The years of direct UV light gradually degrade any free double bonds from the butadiene parts of the ABS down to the hydroperoxide and the manufacturer's don't put enough carbon black pigment into the material to mask this.

The only ways I know to fix that are either black liquid shoe polish or matt black paint; the whitening is irreversible as far as I know, unless someone wants to prove me wrong.....
 
Merlin said:
The only ways I know to fix that are either black liquid shoe polish or matt black paint; the whitening is irreversible as far as I know, unless someone wants to prove me wrong.....
Click to expand...

Not that I want to prove you wrong - I don't. I just want to get your black bumper, black again. I've used an Autoglym product - Bumper care on a number of things.

Bumper Care.jpg

I've used it on old exterior black plastic and rubber, and on the flat black painted exterior trim parts on cars. It brings them right back to black. I even use it on disk drive faces - makes them look like new again. I don't have a black bumper to try it on though. You should give it a shot.

PS: am typing comments on the Wiki at the moment - just need to find your email address, and I'll send them. I'll bet you just can't wait, huh?
 
Merlin said:
Just to show how much of an anorak I have become about this topic....

Have you ever seen black bumpers (fenders) on cars, that gradually turn grey then white under sunlight? Well, that's because the bumpers are made of...yes, you've guessed it.... ABS.

The years of direct UV light gradually degrade any free double bonds from the butadiene parts of the ABS down to the hydroperoxide and the manufacturer's don't put enough carbon black pigment into the material to mask this.

The only ways I know to fix that are either black liquid shoe polish or matt black paint; the whitening is irreversible as far as I know, unless someone wants to prove me wrong.....
Click to expand...

Yeah, that's why I think you cold turn this into a commercial product. There's lots of fadeable plastics in cars, not just limited to old computers. Even if it's too late to patent the now open source formula, maybe you could sell some to the local auto body shops, detailers, etc, or even contract with them to do some piecework for 'em. I'm planning to start experimenting with various junkyard parts (door panels, dashboards, etc) this summer, and mebbe take on some of that kinda work myself if it works out. Then of course, there's the patio furniture, and other items around the household too. A whole lot of people will be willing/able to pay well for that sort of service.

--T
 
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@Terry Yaeger:

While it wasn't viable before because of the cost (using a straight liquid solution that was spent after about 3 days) it is becoming much cheaper.

This paste/gel version is way cheaper than what we were originally doing with the liquid. For example, when we first started I would use 4 gals of H2O2 @ $ 20/gal = $ 80 to de-yellow an Osborne case, while now I now use maybe $ 5 to $ 10 worth of H2O2 to do the same case.

In the last week I've made seven batches, messing with the recipe to see what works best for what (ie: vertical vs horizontal surfaces).
I'll make a few more batches and then post the results, with the associated cost of de-yellowing the items.

PS: I've already done patio furniture - it works great for stuff that's discolored from siting in high sunshine areas. Re: car stuff - you need to be careful with black or dark blue plastics - it doesn't seem to work the same way. I had some undesired results with an Osborne keyboard bezel (dark blue) and a Televideo monitor bezel (black). Experiment (& post the results) first. (Are we allowed to put car part results on a vintage computer forum?)
 
@ Lorne

Thanks for the PM and comments, much appreciated; I'll get on with improving the Wiki later this week.

I am really interested with your recipe experiments, it will be good to compare with the work Tezza has done. It's also interesting that you have costed the difference out of using the gel rather than the liquid, that's a big difference and much more than I thought it would be.

@ Terry Yager

You go ahead son, make your millions from restoring plastics...;)
 
Merlin said:
@ Lorne
I am really interested with your recipe experiments, it will be good to compare with the work Tezza has done. It's also interesting that you have costed the difference out of using the gel rather than the liquid, that's a big difference and much more than I thought it would be.
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Yea, me too. I really have to watch our pennies at the moment and couldn't do any more "experimenting" as such with the recipie despite the relatively low cost.

However, there is still a Colour Genie to do, and some System 80 keys. That's in the pipeline.

The Colour Genie is black and white (err..black and yellow). Give what you've said Lorne, would you recommend not painting/masking the black areas?

Tez


Tez
 
@ Lorne

The Wiki has been spruced up some more now based on your comments, thanks. It should read more logically now.

@ Tezza

Are you a member of Atari Age? If not, could you sign up and lend a hand in the sticky about our project, in the 8-bit forum section?

A guy called Maxkillz is worried that he may have damaged his Atari 800. He is using a gel based on 9% peroxide solution and maybe could use some advice and encouragement from you, as his process conditions were similar to yours.

Thanks
 
tezza said:
Give what you've said Lorne, would you recommend not painting/masking the black areas?

Tez


Tez
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Based on my two experiences, I would definately say don't brush the stuff on black or dark blue areas. The two instances I did it, portions of the darker plastic became lighter - not what you want, when you want a dark black against a bright white.

The problem is, I have yet to find a tape that will stick to the plastic long enough, and stop the mixture from creeping under it, after the tape has been soaked a while. I've tried all kinds of painter's masking tapes (even the real expensive ones), clear packing tape and brown packing tape. None of them worked. And don't use brown packing tape on something like a painted metal logo - it's sticks so good that it pulls the paint off the metal placque.
Thankfully, I don't have any more pieces to do, that have dark plastic adjoining a lighter plastic. I do however, have an IBM 5151 display that has white and grey plastic, and I haven't checked yet but I think the two pieces are molded together so I won't be able to separate them.
If anyone has any ideas of what we could use to mask areas off, they'd be appreciated. Whatever we use, it will have to be very water resistant, and sticky enough to hang on to the plastic at the edges, after its been soaked a while.
 
Here's what I've come up with for costs (subject to a slight change once the final recipe is figured out for the solution):

We have come a long way from the beginning when we were using a liquid solution, instead of this paste/gel version.

Here’s the costs based on what I’ve been doing.

Total initial outlay for solution/gel/paste= $ 54
Consisting of:
1 gal of H2O2 (30% solution) @ $ 21
6 oz Xantham Gum @ $ 14
6 oz glycerine @ $ 12
56 oz tub of Oxy laundry detergent @ $ 7.

Conversion rates:
1 gal = 3875 ml
1 gal = 16 cups
1 oz = 6 tsp

Cost of a 200 ml (approx 1 cup) batch = $ 2.22 per batch
Consisting of:
200 ml H2O2 = $ 1.10
2 tsp Xantham Gum = $ 0.78
1 tsp glycerine = $ 0.33
¼ tsp Oxy detergent = $ 0.01

Actual costs would depend on what quantity of supplies you purchased, where you purchased the supplies, and how yellowed the particular unit is.
An Osborne portable computer for example, with let’s say light to medium yellowing (on a light to medium to heavy to severe (like Tezza’s) scale) should require just a one application treatment. Treating the entire case (both halves) including the small vent cover, power supply cover/area, handle piece, and the keyboard bottom case would require probably two, and at most three, 200 ml batches of paste/gel @ $ 2.22 per batch = $ 6.66. The keyboard keys would be treated in a liquid solution (just H2O2 & Oxy) and would require an additional 2 cups of H2O2 (which could actually be used to treat two or three sets of keyboard keys in succession over a couple days) at a cost of $ 1.31 per cup = $ 2.62.

So, the entire Osborne computer could be de-yellowed at a maximum cost of $ 9.28 (note: this example is based on using the 30% H2O2 solution that both myself and Krye have been using).

Costs not included above: drink mixer, UV lights, gloves, safety glasses, rags, stir sticks, paintbrush, elec usage costs for the mixer/UV lights, labour, etc.


Terry Yager’s gonna get filthy stinking rich off this stuff, and then he won’t even be bothered talking to the likes of us !


.
 
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Yeah, I figger the market can easily support a couple C, mebbe more to do a car interior (dash, door panels, console). Outside is a whole 'nother situation tho, you're dealing with much more than just sunlight (rain, snow, road salt & other road chemicals, ozone & other pollutants (acid rain?)). I think sticking with the old standard, flat-black spray paint will have to do. With fewer people buying new cars these days, there might be quite a demand for detailing older ones.

--T
 
Merlin said:
@ Lorne

The Wiki has been spruced up some more now based on your comments, thanks. It should read more logically now.

Thanks
Click to expand...

Nice job Merlin - very impressive - looks like a very polished article - good summary too !

You could now include some info regarding the cost of the de-yellowing as well (although costs change over time, so maybe not).

I've got some more photos coming for the gallery (including the obligatory original IBM PC of course).
And that's something too !
While the Wiki notes the photos as "Lorne's Osborne 1 experiment", which it was at the time, I now have enough faith in the process to use it on what has been described as "very, very rare", and "the holy grail of IBM 5150's"; a 64K IBM 5150 PC with 1.00 ROMs. I didn't even think twice about using the de-yellowing process on that computer. There wasn't a lot to de-yellow on it, but that says a lot about how far we've come in such a short time.


Suggestion: Post a link to the Wiki article each time you post us that there's an update, so those that come in late in the game, don't have to go hunting for it.

.
 
@ Lorne / Tezza / Krye, etc.

We couldn't have reached the point where we are at now without the massive amount of faith and help that you guys put in, therefore it was only fair that you share in the credit for this project.

I consider myself the "backroom boffin" and facilitator / project manager for the project, however, it would not have received the recognition it has without your valued input.

Thanks guys.

That's a good shout on the updates in the thread Lorne, I'll do that.

We are now at over 200 posts in here too; is it time for us to start Part 3 in the saga?
 
Thanks Merlin,

Good explanation of the science on the wiki. Well done!

However I'm a little concerned about the recipe with regards to Arrowroot. With arrowroot glycerine is certainly not needed, and it definitely (not maybe) needs heating. Also, I used 1/2 the strength of H2O2 mentioned.

Reading the recipie on the wiki at the moment, it looks like Arrowroot can be just substituted for the X gum. This is misleading. Unless you know of others that have tried it as a straight substitute (and it's worked fine) you need to alter the preparation along with the ingredient. if Arrowroot is used the solution ALWAYS needs heating (and just how long and how hot is important) and no glycerine is required as it forms a thick gel.

I'd be happier if you took mention of the arrowroot out of the retrobrite recipe and instead had a link to my modification of the formula. Either that or cut and paste the recipe from my page and insert into the wiki as an "alternative" recipe (Arrowroot variant).

Tez
 
Point taken Tezza; I will amend that later.

Thanks

I think I worked out what went wrong with MaxKillz Atari 800 case; he carried out his process in Florida and the gel dried out very quickly. The result was that although the main surface was not affected, the cracks in the textured surface have gone white. I believe that as the gel dried out, it was drawn into the textured surface through capilliary action, at which point the peroxide content went through the roof, causing the bleaching of the polymer. That's the only mode of failure I can think of that fits what he has experienced.

All is not lost, though; he said that if he wets the case, the white bloom disappears; if he coats the case with a clear acrylic lacquer, it should mask the bloom.

This is definitely something to watch out for if you are in a hot climate and I'll add it to the Wiki later. I think we need a "Problems and Pitfalls" section to warn people about things that could go wrong and how to avoid them.
 
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Merlin said:
All is not lost, though; he said that if he wets the case, the white bloom disappears; if he coats the case with a clear acrylic lacquer, it should mask the bloom.

This is definitely something to watch out for if you are in a hot climate and I'll add it to the Wiki later. I think we need a "Problems and Pitfalls" section to warn people about things that could go wrong and how to avoid them.
Click to expand...

Merlin:
Tell MaxKillz to try some of that Autoglym Bumper Care. I'm almost certain that would solve the problem. It's about $ 10 and he can order it online from www.AutoBodyDepot.com.

A Problems & Pitfalls section is a great idea. I'll come up with a few to put in there.

I've got some more edits ("another" typo) for the Wiki. Will send them later.
 
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