Retrobright: The Yellow Strikes Back

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kbdfr
The Tiproman

05 May 2015, 16:50

Black is so undifferentiated…
Some 20 years ago, a neighbour and friend of mine started replacing all his furniture with black stuff. Painted the doors black. Replaced all curtains with black ones, and so on.
Ever had breakfast sitting on a black chair in front a a black table with black plates, bowls and everything, cutlery with black plastic handles? Even candles on the table were black, and he and his wife both wore black :x

They even ended fitting the whole flat with black carpeting. Fortunately that was about the time I moved, so I suppose I escaped black wallpapers. Does black window glass exist? If so, they surely have some. And probably black light bulbs.

But well, perhaps I'm wrong and now they have only aluminium stuff :lol:

mr_a500

05 May 2015, 16:53

Maybe they went black because their beige walls and furniture kept yellowing. :D

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Chyros

05 May 2015, 18:52

I generally prefer white to black keyboards. Partly because of the colour, and partly because most keyboards that come in black are just really vulgar and tasteless, almost to the point of being obscene (like almost all modern black, backlit keyboards).

Some old keyboards in black are really great-looking though. Black Focus FK-2001, yummy ^^ .

mr_a500

05 May 2015, 23:51

I think white with black is a nice combination (as long as the white isn't yellowed) like this:

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...and I can tolerate a beige case when the keys are black, like this:

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Incidentally, aluminium with black keys colour scheme isn't entirely modern, as you can see - 1981 TI-99/4A and 1982 Kaypro II:

Image

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Yes, this post is a shameless flaunting of my keyboard photos. :mrgreen:

(at least I resisted the urge to post all my keyboards with blue or brown keys)

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Redmaus
Gotta start somewhere

05 May 2015, 23:57

Brown keys you say? :roll:
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mr_a500

06 May 2015, 00:00

Yeah, dark brown... like this:

Image

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You got a problem with brown keys? :)

Wow, that Xerox is either super-yellowed, or somewhere in the US where they love yellow lighting.

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Chyros

06 May 2015, 01:01

Some more details about the process, for those who are interested. Sorry if I get too technical in the end xD .

ABS is basically a "mixture" of three polymers, those of acrylonitrile, butadiene, and styrene. Of the three, it's the polybutadiene phase that's most vulnerable. Exposure to UV leads to a discolouration of the ABS as well as a considerable loss of impact strength. Once this degradation has started, it can be reversed as well as combated, but will over time always return.

When exposed to UV radiation, the methylene bond in the trans-butadiene structure is photolysed, which yields an allylic radical. This species can then react in several ways, either forming more radicals, or reacting with molecular oxygen to form oxygenated species, such as hydroperoxides, esters, and unsaturated carbonyls. The peroxide species are susceptible to decomposition under the influence of UV to form more radicals, accelerating the process. The carbonyl materials are responsible for the yellowing, and are also capable of engaging in cross-linking reactions with the rubber component of the material, which results in destruction of the elastomeric properties of the material and a concomitant embrittlement and loss of impact strength.

Sauces:
-Piton et al., Polym. Degrad. Stab. 55, 1997
-David et al., Polym. Degrad. Stab. 84, 2004
-Pickett et al., Polym. Degrad. Stab. 85, 2004
-Rajan et al., J. Appl. Polym. Sci. 124, 2012
and others

Once the material has been degraded like this, it has become susceptible to attack by oxygen as well as UV. Hence, even in dark rooms, materials will form which cause yellowing, as well as generate more radicals. If your board is yellowed, you can temporarily make it look nicer, but it will never be fully stable anymore.

(in other words, forget the bromine rubbish :p)

mr_a500

06 May 2015, 01:09

Fascinating... and tragic. So, as expected, there's no hope. Keep those plastics away from the damn sun!

Every time I see an eBay auction showing a vintage computer sitting in the bright sun, I think, "idiot!"

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Redmaus
Gotta start somewhere

06 May 2015, 01:37

mr_a500 wrote: Fascinating... and tragic. So, as expected, there's no hope. Keep those plastics away from the damn sun!

Every time I see an eBay auction showing a vintage computer sitting in the bright sun, I think, "idiot!"


Right. I don't mind retrobrighting every few years or so though. Is there a place where I can see your whole collection a_500? I like the look of these boards and my only board with spherical keys is the one you saw in my previous post.

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Mal-2

06 May 2015, 03:38

mr_a500 wrote: Every time I see an eBay auction showing a vintage computer sitting in the bright sun, I think, "idiot!"
Unfortunately, good lighting is necessary to get good pictures. This can either be artificial or natural, and most people don't own a bunch of photo-quality artificial lighting.

Potato quality pictures will likely reduce the quantity and limit of bids. Thus, what's in the seller's interest (to maximize sale price by taking better pictures) is not in the best interests of the item being sold — but why should they care, they're selling it!

Unless you can convince all prospective buyers — experienced and inexperienced alike — to tolerate potato-grade pictures as the norm, and shun auctions with high-quality photos, I'm afraid a few minutes of UV exposure is just the price to be paid for the equipment changing hands.

andrewjoy

12 May 2015, 20:44

Just started my first test of retrobriting.

I did not want to stain anything so i want for the full breaking bad set-up

Image


just 10% H2O2 see how it works on some WYSE double-shots

quantalume

15 May 2015, 05:41

Just store your stuff in a cold, dark vacuum.

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Redmaus
Gotta start somewhere

15 May 2015, 06:17

andrewjoy wrote: Just started my first test of retrobriting.
just 10% H2O2 see how it works on some WYSE double-shots

I have wyse doubleshots that need a touch up soon, really looking forward to the results! :)

Also, is there any way to make the lettering "bolder"? I feel my wyse doubleshots somehow got faded after cleaning them. :|

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seebart
Offtopicthority Instigator

15 May 2015, 09:14

andrewjoy wrote: Just started my first test of retrobriting.
I'm looking foreward to your results, keep us posted please!

andrewjoy

15 May 2015, 11:00

Its looking good so far, thawing caps in a big tub with a load of it is not the best but it is ok, they need another treatment but the look way better than they did. Now i have a set of only slightly yellowed wise caps ( the thick ones). Funny the other set that was mixed in ( the thin wise caps) cleaned up faster ? The space bar is almost done ! just a few patches to clean up and its almost 100% back. This was food grade 11% H2O2 5l for 11 quid

i need some corn starch ( is that called cornflower in the uk ?) to thicken it up and then just use the bag method . for the smaller caps. Looks like it will work well on my M0110

I was thinking of buying a few UV lamps and making a retorbirting box . lamps on the top and a box made of mirrors

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seebart
Offtopicthority Instigator

15 May 2015, 12:18

hmm sounds pretty good. I think I'll try the mother earth sunshine method this summer, depending how this summer turns out.

andrewjoy

15 May 2015, 12:22

it works but its not ideal or even. The UV is best and the mirrors will get rid of the need for the paste method , if you make the box water tight you can fill it with the H2O2 and get light from all sides.

Am i correct in thinking that mirrors reflect UV , they should do right

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seebart
Offtopicthority Instigator

15 May 2015, 12:26

I was planning on using this gel like stuff:
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obviously I want to avoid the horrid "marble effect". So a bath might be better. I have nill experience in this. But the good old sun is stronger than any light.
andrewjoy wrote: Am i correct in thinking that mirrors reflect UV , they should do right
good question. Not sure.

andrewjoy

15 May 2015, 12:30

apparently that stuff works quite well , but its always best to submerge in liquid if possible.

Also been doing some reading on reflecting UV light, apparently mirrors are crap for it, aluminium is the best common material for reflecting it so aluminium foil in a box will work for my idea.

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Chyros

15 May 2015, 13:53

andrewjoy wrote: Am i correct in thinking that mirrors reflect UV , they should do right
No.

blain.s

19 Aug 2015, 16:19

Sigmoid wrote: Well it's never pointless to look for better solutions, but I honestly don't see the problem. Flame retardant plastics yellow with age, this is a known fact of life. Plastics in general also become more brittle with age. I guess the final solution will be high quality 3d printing or some other way to replicate old cases with 100% accuracy out of brand new plastic (like the solution for cataracts is the implantation of new, artificial lenses)..
Agreed. I was just looking into retrobrite for my A1200 (just dug it out of the cupboard - not looking too good)

There's a Kickstarter for new A1200 cases but it doesn't look like it will succeed.

https://www.kickstarter.com/projects/a1 ... -new-molds

Shame because they'll be available to buy if they get funded and AFIK they're looking into making cases for other Amigas too. Only 24hrs or so left.
Sigmoid wrote: So yea. You can't magically make 30 year old ABS into new ABS. Retrobright is a cleaning method. You take an old, crusty-with-bromide c64, and then blow everyone's mind with your flashy new-looking c64 at the scene parties. If you clean something only to put it away for years, it will likely get yellow again. Heck, NEW-new c64s will get yellow in 4 years. I remember seeing lots and lots of them with that crusty, shiny yellow look back in the day when they were still manufacturing them!
(Also I wonder why you'd painstakingly refurbish something only to put it away for 4 years (then again I never was a collector, I just like old technology).
Looks like I'll retrobrighting my old dear then.

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XMIT
[ XMIT ]

19 Aug 2015, 16:34

Chyros wrote: When exposed to UV radiation, the methylene bond in the trans-butadiene structure is photolysed, which yields an allylic radical.
If this is the root cause then this suggests that all ABS plastics are susceptible to this failure mode. Why, then, is it only common in plastics from a particular era? Are there additional UV resistant additives, coatings, etc. that are in somewhat ubiquitous use?

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seebart
Offtopicthority Instigator

19 Aug 2015, 16:46

XMIT wrote: Why, then, is it only common in plastics from a particular era?
How do you know that? The only logic can be that plastics with specific traits were produced in large numbers that happen to react this way. But since we know the yellowing is quite sporadic even this will be very hard to prove. I bet there are even fluctuations within the properties of the plastics of the same series of keyboards produced in the same year. IBM keyboards being the best known exception. The variables are still quite unknown IMO.

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XMIT
[ XMIT ]

19 Aug 2015, 16:50

seebart wrote:
XMIT wrote: Why, then, is it only common in plastics from a particular era?
How do you know that?
I guess I don't know this for certain. Anecdotal evidence with the Super Nintendo suggests that later models, using modified ABS plastic formulations, were more resistant to yellowing. My question was with regards to those formulations in particular since the failure mode Chyros proposed would be applicable to all ABS plastics.

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seebart
Offtopicthority Instigator

19 Aug 2015, 16:53

XMIT wrote: My question was with regards to those formulations in particular since the failure mode Chyros proposed would be applicable to all ABS plastics.
OK I see. Got it. A universal solution is to ALL plastics seems quite impossible anyway.

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XMIT
[ XMIT ]

19 Aug 2015, 17:15

seebart wrote:
XMIT wrote: My question was with regards to those formulations in particular since the failure mode Chyros proposed would be applicable to all ABS plastics.
OK I see. Got it. A universal solution is to ALL plastics seems quite impossible anyway.
Right. Preventing UV damage is a theme. There are plenty of automotive products that are really just plastic-safe UV barriers. Using those seems easy enough. I'm more interested to know about differences in ABS plastic formulation (and too lazy to research this myself :roll: ).

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seebart
Offtopicthority Instigator

19 Aug 2015, 18:50

The only testing that would even amount to anything is hardware of the same production series (the closer the better) AND where the sotrage conditions history is known. I have read of such long term retrobright tests and even there the results were not predictable. UV damage is not the only factor. BUT I can't prove anything. I've never even tried to retrobright yet once myself. Everything that I have read about it amounts to varied results and some unknown factors.

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fohat
Elder Messenger

20 Aug 2015, 01:54

I have tried it half a dozen times, or so, with a couple of brilliant successes but mostly pitiful failures.

Once upon a time I heard that Apple AEKs and AEK2s used more bromine for fire resistance and it accelerated the yellowing.

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Chyros

20 Aug 2015, 10:10

XMIT wrote:
Chyros wrote: When exposed to UV radiation, the methylene bond in the trans-butadiene structure is photolysed, which yields an allylic radical.
If this is the root cause then this suggests that all ABS plastics are susceptible to this failure mode. Why, then, is it only common in plastics from a particular era? Are there additional UV resistant additives, coatings, etc. that are in somewhat ubiquitous use?
Very good question. Yes. There are a whole bunch of different stabilisers, additives, etc. in all plastics we use. Heck, most or even all of them still contain the catalyst used to polymerise these materials. These all have different interactions with UV, heat, oxygen, etc. etc. etc.

One account of what I've read suggests it's not the trans-butadiene bond itself that absorbs UV, but rather impurities in the material, and the heat and formed radicals from that reaction is what reacts with the trans-butadiene, which would explain why the reactivity is uneven across time. As impurities and additives are more or less unavoidable in the final material during industrial processing, I guess it makes sense that that study I quoted previously doesn't distinguish between "pure ABS" and "industrial ABS".

Regardless, no matter what timeframe your ABS material is from, it should be susceptible to at least SOME degree of yellowing I guess. Considering retrobriting uses UV radiation to perform the process I suspect that when the yellowing does come back it should be worse AND yellow faster after that, so I'm not sure I'd recommend it.

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seebart
Offtopicthority Instigator

20 Aug 2015, 10:32

It is documented that the yellowing returns. Again, the results vary quite a bit.

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