Retrobrighting Vintage Casio's Keys? (SA-21)

[timbr]

Hi all, 

 

since I'm starting a little collection of vintage toy/cheapo keyboards, I recently bought an old SA-21 (from the 1990s) as 'new-in-box' item on *bay. 

 

Of course, it is anything but new. Though it is unscratched, as far as I could see, it is clearly used (used batteries from a different retail store chain inside). The (private) seller won't take it back, and I'm not sure it would be worth the return postage anyway. 

 

Two things are really annoying: 
1) The batteries are rattling when I move the keyboard. 
2) All the keys are heavily (and evenly) yellowed. 

 

Two related questions before I get to the subject matter: 
Is the batteries rattling phenomenon a known issue? They don't rattle sideways, but the battery compartment seems to be too wide in diameter. I would have expected there to be at least some kind of padding that prevents them from rattling.

 

In the same vein, is key yellowing a known issue? I would expect a keyboard sitting in its box not do develop that problem, disregarding the duration of storage. 

 

Now, having come across the idea of 'retrobrighting' old plastic housings, I was thinking of trying to apply that to the yellowed keys.
For those who might not know, 'retrobrighting' is basically bathing (or otherwise covering) plastics in Hydrogen Peroxide (plus some additives) and leaving it in the sunlight or under UV light for a day or so. This should be able to reverse the yellowing. There are numerous YT videos about it and there used to be a wiki on http://retr0bright.wikispaces.com, no idea where it went, but pages (up to ca. 2012-14, oder ones work better) still accessible on archive.org.

 

I have seen several examples of successful retrobrighting of computer gear, but I have never seen it applied to keyboard keys. 

However, I'm not sure this process is suitable for the kind of plastics the keys are made of, and whether the phenomenon in the keys is caused by the same flame retardants and Bromine in the first place. 

 

Anyone ever tried 'retrobrighting' vintage keyboard keys? Any successes or failures? Any other thoughts?

 

TIA

[Chas]

Hi @timbr,

 

Welcome to the wonderful world of collecting vintage/ toy keyboards! Be warned, it's a rabbit hole that can go very deep - don't ask me how I know...!

 

To answer your questions:

 

1. Batteries rattling around: Most low end keyboards that take batteries normally hold them into place via two means - the tension of the springs and also some compressible foam attached to the back of the battery cover. With age, this foam often dries out and disintegrates, meaning that when in place the battery cover no longer applies pressure to the batteries below it. It is possible to replace this stick on foam with a modern equivalent, and one such example that I've seen used is draught excluder tape that can be bought in rolls from a home improvement store. 

 

Another possible cause for the batteries rattling around could be that some of the cheap non branded batteries are slightly smaller in diameter than branded batteries, causing them to fit more loosely in the battery compartment. If you can, try some branded batteries to see if that solves the problem.

 

2 Yellowed keys: This is an issue with many plastic items as they age, very common with the vintage white/ beige computer and keyboard cases, as well as the keys themselves, and can also affect older musical keyboards. Often it is caused by prolonged exposure to UV light  (sunlight) causing the surface of the plastic to yellow, sometimes it can be caused by chemicals within the plastic themselves and/ or the plastic degrading over time. Some plastics are more susceptible than others, and some respond to retrobrighting better than others also. Among my large collection of Casio/ Casiotone keyboards, some of the keyboard keys appear to be completely unaffected, whereas others have yellowed considerably. The worst for me is my 1980 CT 201, and its selection switches have also yellowed as well. When I took it apart there are parts of the keys that were covered by the housing (and hidden from UV light), and you could see the original bright white coloring that they were  when new. My dilemma is that with it being such a vintage keyboard, as well as historic by being the first Casio(tone) musical keyboard model released, should I "restore" it back to original, or do I keep it as it is and accept it as age related patina? Asides from the yellowing giving it a vintage charm, there are also some scuffs along with wear and tear on parts of the housing, so though I might be able to make the keys and switches look new, I can't do the same with the the casing. Decisions decisions!

As to your SA-21, that model being many years newer doesn't look anywhere near as old and as vintage as a 1980 CT201, so I can understand that yellowed keys won't have the same charm. There's no reason as to why you can't try retrobrighting them, though as with any chemical process, try it out on a small discrete area first to see if A: It will actually work, and B: to ensure you don't get any unwanted/ adverse reactions. The SA-21 should be a fairly simple model to take apart and you should easily be able to separate just the while keys from the rest of the keyboard. IIRC, they'll probably all be on a strip with the black keys being on a separate strip. You'll also be able to test out the retrobrighting on an area of the keys that are hidden under the casing to check for adverse reactions. Oh yes, I've also seen some people have success with whitening plastics by just leaving them outside in direct sunlight - no chemicals needed. However, whichever method you choose to use, be warned that over time the plastics can yellow again, and some people have experienced the plastic becoming more brittle after treatment.

Out of interest, could you share some photos of the keyboard so we can see how much the keys have yellowed?

Hope this helps!

Edited September 10, 2022 by Chas

[Jokeyman123]

To get this retrobrighting right-and i have done it to restore a few musical instruments-just the peroxide alone might not work  (I use the kind of jell one might use on your hair-I considered bleaching my hair to match my keys, but then my teeth already matched my older keys-before I bleached them😋 now i'm being silly-but back to  my point-I needed to set these out in the sun, with the peroxide paste-and it needs to be made into a formulation that is thick enough not to drip on anything else-i always mask off everything-and not too thick that the sun will dry it out before it works. Even a few hours in our now martian-level sun did it. (No offense fellow space creatures)...

I also recall needing to pay attention to the percentage of peroxide in the brand i bought-too little won't work, too much-might damage the plastic, bleach can penetrate if it is too strong a formula. I think I used something like 20% solution. 

[timbr]

The keyboard, the box (below), and a blank sheet of copier paper for comparison. 

 

Sorry, but I don't have enough time for a more complete response atm. Hope to come back to it later today.

[CYBERYOGI =CO=Windler]

AFAIK Casio's aren't overly light sensitive, but by design the keys may be rather ivory colour than plain white to mimic the key colour of traditional pianos. One reason for the rumbling batteries and yellow keys inside your SA-21 may be leaked batteries, those acid vapours decompose the foam rubber strips (also damage LCDs) and can yellow the plastic. A hint for this would be when the inside (which gets barely exposed to sunlight) is as yellowed or even beiger than the outside of the keys.

 

However my TrendLine MC3700 (bought used, likely a Medeli product) does have extreme sunburn from the previous owner, i.e the white keys are discoloured deeply orange and the coloured buttons brownish (no, it's not nicotine). I haven't dared to use bleach yet because I feared things to crumble apart. The old eBay photo on my website does not show the actual condition of the thing.

 

http://weltenschule.de/TableHooters/Fujiyama_KS-37.html

 

I also own a big green DJ toy keyboard "Synth Mixer" (likely made by Potex, bought used on eBay) which has some of the keys noticeable yellowed. Also the homecomputers and game consoles (Atari 800XL, NES etc.) I had on the desk in 1990th became definitely beige instead of grey.

 

And also the beige of my main PC (Highscreen Colani bigtower, very modded with 2 mainboards inside) and its Chicony keyboard turned beiger by sun over time. But I can not use bleach there because the case has printed logos and is painted inside with EMF shielding paint, and I have additionally hotglued dozens of LEDs and connectors with thin wires into the back of the case front.

Edited September 13, 2022 by CYBERYOGI =CO=Windler