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Discolored "Sea Foam Green" WE 500 on eBay restoration discussion

Started by AliceWonder, March 25, 2023, 06:58:49 AM

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AliceWonder

Obviously it's an aqua, but describing it as "sea foam green" was kind of creative...

I'm not going to buy it, but it's very tempting to find a discolored 500 like that (but cheaper) just to learn how to restore the original color, as an aqua 701b/702b is on my want list and I understand most out there are discolored.

https://www.ebay.com/itm/304703911352

MMikeJBenN27

If you find a way to restore the color on hard plastic, that would be a boon to us, as peroxide only seems to work on the soft plastic, and many of us, myself included don't want to use sand paper.

Mike

TelePlay

Quote from: MMikeJBenN27 on March 25, 2023, 01:52:02 PMIf you find a way to restore the color on hard plastic, that would be a boon to us, as peroxide only seems to work on the soft plastic, and many of us, myself included don't want to use sand paper.

http://www.classicrotaryphones.com/forum/index.php?board=24.0

Peroxide is a chemical treatment that does nothing more than further damage the chromophores mixed into plastic when molten to create a color.

Removal of the top, thin layer of damaged plastic is the ONLY way to restore discolored plastic, hard or soft.

Removal is accomplished by paper or chemical solvent sanding.

The board link above is replete with "how to" procedures posted by members who have successfully restored discolored plastic, even after it has been further damaged by trying to use plastic peroxide.

There is no chemical method/treatment that will recreate (restore or re-synthesize) the original fragile chromophores (easily damaged by UV radiation from sun light) imbedded in the plastic



to create a color other than removal of the damaged thin, top layer of plastic.



http://www.classicrotaryphones.com/forum/index.php?topic=23386.msg234545#msg234545






FABphones

Below are two 'Before and After' examples of phones I have colour restored using the Chemical Sand method.

The first example is ABS, the second is Polystyrene.

http://www.classicrotaryphones.com/forum/index.php?topic=20761
and
http://www.classicrotaryphones.com/forum/index.php?topic=22402

A collector of  'Monochrome Phones with Sepia Tones'   ...and a Duck!
***********
Vintage Phones - 10% man made, 90% Tribble
*************

Stormcrash

Quote from: MMikeJBenN27 on March 25, 2023, 01:52:02 PMIf you find a way to restore the color on hard plastic, that would be a boon to us, as peroxide only seems to work on the soft plastic, and many of us, myself included don't want to use sand paper.

Mike


Peroxide should absolutely work on "hard plastic" ABS. That is what most of the retro computers and games consoles are made of that people retrobrite using peroxide. I would actually worry that it might really damage Tenite soft plastic considering Tenite can be surface melted with rubbing alcohol a much weaker solvent.

That said retrobrite does usually seem temporary (though it seems some like Adrain on Adrian's Digital Basement might have luck using 303 Aerospace protectant to protect and rejuvinate the plastic surface), and there were a few reports on this forum that after retrobrite the surface would no longer melt with acetone

One thing I still want to investigate personally is a technique mentioned on this forum of leaving the part out in the sun and that the natural light radiation will undo the yellowing. A few days wouldn't be enough to cause sun fading and given what I've learned about interior light/glass I almost suspect that the outdoor UV-C that windows block it what can trigger the breakdown of the yellow bromides (Adrian has had luck using peroxide and very blue near UV light to retrobrite indoors with no heat using a similar principle)

FABphones

The thread linked below details my experiments with Peroxide (on both ABS and Bakelite).

http://www.classicrotaryphones.com/forum/index.php?topic=22587

Image below shows the result on a blue ABS shell which had turned green.

Chemical Sanding remains my preferred method.
A collector of  'Monochrome Phones with Sepia Tones'   ...and a Duck!
***********
Vintage Phones - 10% man made, 90% Tribble
*************

TelePlay

What you are referring to is the bleaching of once light colored plastic that has turned yellow due to the damage of chemically synthesized chromophores that were imbedded in the plastic to reflect all light, make it look white.

This is the same as adding bleach to a load of white sheets to remove the yellow tinge. Works on white but not colors.

It is impossible to restore, to re-synthesize damaged chromophores, the uniquely created chemicals placed in plastics to absorb some wavelengths and reflect others, to create a specific color in ABS, Tenite or any other colored material.

Never saw a "colored" computer housing/keyboard.

Here's a pink 500 bezel that was treated with peroxide by another member. It destroyed the bezel. The damage was so deep it could not be removed by sanding. It is impossible to control the exposure of peroxide on plastic due to each plastic part being made from differing batches of plastic, inconsistent concentrations of peroxide over different areas of the plastic (in this case the lower center of the bezel was subjected to higher peroxide concentrations) and the length of time for peroxide exposure.

You can bleach white all you want but bleach/retro bright/ peroxide (all oxidizing agents) will never restore discolored (color) plastic. It may seem to work to brighten up lighter colored plastics but only removal of the discolored layer exposing the original plastic colors, exposing the plastic layer with the original, undamaged chromophores, will restore discolored plastic to its original color.

Chromophores are complex molecules created using dozens of different organic chemical reactions to create a compound that wii selectively absorb and reflect different wavelengths of visible light and once split, broken apart, damaged by UV radiation when within the plastic, they can not be fixed/repaired/restored by using any oxidizing agent (bleach or peroxide), which is simply a bleaching/oxidizing chemical reaction, they can only be removed. It takes a long chemical process to create a chromophore before it becomes the desired compound to make a specifically colored plastic, is mixed into clear or white plastic to create a colored plastic.

Fixing the damaged molecules already inside the plastic is not only chemically impossible but attempting to do so with an oxidant will also affect existing undamaged chromophores leading to unexpected and inconsistent results.

Restoring discolored plastic is not an easy task and their are NO short cut chemical processes that will work on colored plastics.


TelePlay

I must add the decision to color restore a phone's plastics requires evaluation of the plastics.

While most discoloration is due to environmental reasons (UV light and atmospheric chemicals and cleaners) over time, these causes result in a thin surface layer changing color which can be removed relatively easily.

However, some plastics mixtures change color due to instability of the components used to make the colored plastic over time - the color changes all by itself. This type of color change is deep if not all the way through the plastic and difficult to impossible to remove.

The easiest way to check which applies is to look at the inside of the housing. If the interior is the original color, the discoloration is due to environmental agents, is a thin layer and can be removed relatively easily.

If the interior is discolored the same as the exterior, the color change is due to unstable original compounds, is quite deep and will be very difficult to impossible to remove.

=============

As noted above, plastics subjected to retro-brite can become surface hardened to the point where solvents will not dissolve the treated plastic.

This is a known and reported artifact of discolored plastic. In the discoloration process, the destruction of original chromophores, the surface also becomes hardened, hardened to the point that pure acetone will not dissolve discolored ABS plastic.

It is also known that if using pure acetone on a cloth to remove discolored ABS, after removal of that discolored plastic the acetone will more quickly dissolve the underlying undamaged, original colored plastic - the cloth will begin to stick to the undamaged plastic (a good way to know when the discolored plastic has been removed).

I proved this by taking a few plastic chips off of a severely discolored 302 Tenite housing and placed them in a vial of pure acetone in 2018. While the inside of the chips saw the undamaged plastic dissolve off the chips in a month or so, the hardened exterior (about 3/32 thick) did not dissolve, the damaged, hardened plastic remains intact after 5 years in pure acetone.

If restoring plastic that has hardened, the best approach is to start with 320 grit dry sandpaper to score and remove most of the hardened layer.



MMikeJBenN27

Maybe I didn't do it right, as it certainly hasn't worked for me.

Mike