Whitening a yellowed IICI: first step.

[Macbuk]

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Waiting for a better work with a lens to remove yellowing around the graphic sign "macintosh IICI", clean with water and apply a clear polish coat. I'm also waiting delivering of a daystar 040 i've bidded for on ebay.

 

[register]

What kind of treatment did you give the surface to remove the yellowed film on the surface ? Exact desciption of the procedure, tools and cleaning agents would be welcome.

 

[Macbuk]

Hi there... i'm writing from italy so i'm not sure to use the correct technical terms. Basically for this first step i used

- 180 grit sandpaper

- 300 grit sandpaper

- 150 watt "square plate type" orbital sander with 4 mm poliuretane soft layer between plate and sandpaper.

- 20 minutes of work including all 5 faces (i've left unaltered the bottom)

I guess i've removed about 150-300 micron of chemical modified plastic with 180 sandpaper. Then i refined the surface with 300 sandpaper in order to hide and avoid any sign of mechanical work. Grooves and fissuration were treated succesfully using the edge that sandpaper makes surrounding poliuretane along the border of sander square plate.

Surface is now a little smoother than original but it still retains part of the original plastic texture, i guess, because of the original "particled" polymer. Next fase i already tried on a severely yellowed mac LC implies the use of a clear coat polish like the one used to remove scratches and make car shining. I still have to address the "para-serigraphy" yellowing with a lens.

My apologies for english spelling.

 

[bmacsys]

Hi there... i'm writing from italy so i'm not sure to use the correct technical terms. Basically for this first step i used
- 180 grit sandpaper

- 300 grit sandpaper

- 150 watt "square plate type" orbital sander with 4 mm poliuretane soft layer between plate and sandpaper.

- 20 minutes of work including all 5 faces (i've left unaltered the bottom)

I guess i've removed about 150-300 micron of chemical modified plastic with 180 sandpaper. Then i refined the surface with 300 sandpaper in order to hide and avoid any sign of mechanical work. Grooves and fissuration were treated succesfully using the edge that sandpaper makes surrounding poliuretane along the border of sander square plate.

Surface is now a little smoother than original but it still retains part of the original plastic texture, i guess, because of the original "particled" polymer. Next fase i already tried on a severely yellowed mac LC implies the use of a clear coat polish like the one used to remove scratches and make car shining. I still have to address the "para-serigraphy" yellowing with a lens.

My apologies for english spelling.

Don't apologize. You speak good English. Great job on the IIci. I have had luck using a solution of bleach and leaving the Mac in the sun to make mildly yellowed cases come back to life.

 

[bigD]

I have had luck using a solution of bleach and leaving the Mac in the sun to make mildly yellowed cases come back to life.

How concentrated is your bleach solution? I'm thinking of trying this myself.

 

[bmacsys]

I have had luck using a solution of bleach and leaving the Mac in the sun to make mildly yellowed cases come back to life.

How concentrated is your bleach solution? I'm thinking of trying this myself.

I probably went 40% bleach. I rinsed then used a bit of Comet for a little abrasiveness, rinsed and bleached again. Let dry in hot sunshine. Worked good.

 

[flyingtoasteroven]

Sounds effective, but I don't have the guts to use sandpaper. I recently came into possession of a crap IIci case, so I'm going to test my old method for keys: straight in the dishwasher. Obviously this will only work if I get all the electronics out.

OK, technically the whitening will work whether or not I destroy the board.

 

[Temetka]

Great job on the IICI. It looks brand new.

You english is pretty good. Far better than my italian (or lack thereof).

 

[tmtomh]

Very nice whitening job! It's impossible to restore the original color without altering the texture, but as long as you don't make it shiny-smooth it will like nice when whitened.

Question: you say you want to put a polish coat on it at the end? Is that because the sanding has left it feeling gritty and you need to put a sealer on it?

M

 

[Macbuk]

Hi all.

As said, after have it refined with 300 grit paper it has lost any sign of sanding procedure but the surface has become more... i would say "velvety", something far remembering soft-touch surface used on black macbook.

However it hasn't become completely smooth nor shining because of "particled" polymer composition. After a closer look to the surface of an original mac (i've some of them in very good condition, you can take a look over them clicking on my signature link) i've noticed dircct light (sun or camera flash) reflecting into something like a thin clear layer but i've some concerns if it has been acquired because of age and/or cleaning procedures over time.

This is the main reain reason why i've already tried on a mac LC the use of a car like scratch remove polish with excellent results. The aim isn't to obtain a shining awful surface; is indeed to obtain a surface virtually indistinguishable from the original. I havent done yet because of serigraphy problem that requires time, patience and precision.

Regards.

 

[register]

Did anyone try to paint a case in platinum grey? Is a colour code available to get an exact match of the colour as well as the gloss? What kind of chemical base of the paint would be compatible to the ABS plastic of the case (acrylic, polyurethane or else, what solvants to be used)?

The coloured Apple sign pops out easily using a pin to push gently from inside the case (there is a small hole allowing some trapped air to escape when the Apple sign is mounted). So one could paint after dismantling the machine without the need to mask any details. A good paint job could restore the original coulour without changing the texture, and would not yellow any more.

Only problem would be the writing of the Mac's nameplate. This could be fixed with a laser cut sticker on transfer film. The result would not be the original, not rising the value from a collectors point of view, however.

 

[Macbuk]

A good paint job could restore the original coulour without changing the texture

Unfortunately a paint job thick enough to avoid rapid wearing, even if you use solvent-diluited paint mixture, will change the texture. Furthermore a paint job will generate unremovable paint collection along grooves. You have good chances to irreversibly ruin your mac at a closer look. But if you had a cheap LC, i guess it might be worth a try.

If you really want restore rougher textures you could use 180 sandpaper and an hot iron imprinting its texture on warm plastic even if I find it useless cause i'm sure noone if temporaneously blinded will easily distinguish the original and the reworked texture because the latter is still rough.

 

[trag]

Has anyone tried a base such as lye on their plastics? My thought is that if the yellowing is caused by slow oxidation, the application of a reducing agent might undo some of that oxidation. Of course, it may just remove oxygen (or other negative ions) from other portions of the molecules, but it is worth a try.

Hmmmm. Perhaps an ammonia dip?

 

[beachycove]

Concentrated bleach can indeed work wonders, but it takes a long soak, one has to keep case metals out or it gets eaten, and alas, the treatment seems not to work in every case (or, should that be, "on" every case?). The metal issue affects what you can do with some bezels, e.g., where there is metal attached to the plastics. A little surgery might be needed in these instances.

My best success has been with a Q650 bezel, which came out of the bleach after a week or more looking spanfire new. It had previously been a sorry sight, yellow and forlorn. I have also had good luck with a DuoDock lid, which I renewed a side at a time. It took weeks, but the results were excellent.

I reckon that a minute quantity of the surface can be dissolved at a uniform rate using this method, which, if smelly, is at least cheap. But it has to be concentrated bleach.

There was a post from the UK, I believe, some months ago which described use of another off the shelf product for these same purposes. I can't seem to find it, though....

 

[Unknown_K]

You guys know that old computers will end up being like old coins, if you strip the surface layer off nobody will want to buy them.

 

[Charlieman]

Whitening toothpaste? It contains a mild abrasive to remove light dirt from teeth enamel. Plus a very mild bleaching agent that is not aggressive. Suitable for lightly tanned Macs?

Thinking chemically, we need an oxidising agent that causes less wear than bleach or ammonia. Any agent will probably weaken the case on the outside (10% penetration) but we can't afford to weaken the inside. Any suggestions for a long chain oxidiser that will get tied up by ABS plus filler?

 

[flyingtoasteroven]

You guys know that old computers will end up being like old coins, if you strip the surface layer off nobody will want to buy them.

Interesting you should bring this up, because my primary field is numismatics. It is true that you should never, ever clean a coin as a collector. Now don't get me wrong, ancient and medieval coins which have been under the ground or in the ocean for centuries will have been, in some manner, "cleaned" before they enter the collectors' market. But one must be extraordinarily careful to distinguish between mechanically/physically removing dirt or debris and chemical restoration from any serious oxidation or sulfide formation. Chemical cleaning removes the metal oxides -- it can never restore them. As such it is verboten to clean any modern coin.

Keeping this in mind, I'm not really sure of the real reason computers, specifically platinum macs, get yellowed. It mac be for a similar reason as white house paint, or it may be for a similar reason as plastics. I do know that PVC plastics will form a thin layer of yellowing due to the UV light in sunlight. (Similarly it can form metal chlorides -- don't put your coins in PVC holders such as those intended for cards or paper products) This layer protects the underlying PVC from furthur damage and it can be removed. However, many plastics also contain cheap fillers, and I cannot speculate what happens to them.

Food for thought.

 

[OtakuMegane]

Keeping this in mind, I'm not really sure of the real reason computers, specifically platinum macs, get yellowed. It mac be for a similar reason as white house paint, or it may be for a similar reason as plastics. I do know that PVC plastics will form a thin layer of yellowing due to the UV light in sunlight. (Similarly it can form metal chlorides -- don't put your coins in PVC holders such as those intended for cards or paper products) This layer protects the underlying PVC from furthur damage and it can be removed. However, many plastics also contain cheap fillers, and I cannot speculate what happens to them.
Food for thought.

I don't have the link any more but there was a nice article and discussion somewhere about the Super Nintendos yellowing and the conclusion was it had to do with how well the plastic was mixed with the flame retardants and what sort of fillers might be used. Exposure to open air/UV/etc. interacted negatively with the mixes that were too far off. If the mix is how it should be and without cheap fillers, you won't get any yellowing, or very mild amounts. And of course every time they make a batch it can come out differently, which is why on some SNESs, half is yellowed, half is perfectly fine; the parts were from different batches.

For lightening Macs I just use an even 50/50 mix of Clorox Outdoor and water, give it some good sun exposure and spray it over 3-4 times. Even very badly yellowed Macs I can at least get down to a much more pleasing beige color. Milder yellowing can turn out virtually indistiguishable from the original platinum. The process preserves the texture but does kill some of the sheen. Still experimenting with the best ways to restore that.

One thing to look out for: some Macs have that silver/grey paint that's used as an EM shield in place of real metal. Don't let it be exposed to any cleaners and not even water if you can help it, otherwise it'll crack and peel into a horrid glittery mess.

 

[Charlieman]

For lightening Macs I just use an even 50/50 mix of Clorox Outdoor and water, give it some good sun exposure and spray it over 3-4 times. Even very badly yellowed Macs I can at least get down to a much more pleasing beige color. Milder yellowing can turn out virtually indistiguishable from the original platinum. The process preserves the texture but does kill some of the sheen. Still experimenting with the best ways to restore that.

This is a very aggressive recipe that will whiten the case (definitely) but which will reduce the strength of the plastics. We are looking for a recipe that will whiten the outside of the Mac without attacking the structure of the case.