About yellowing


21 Jun 2020, 18:18


I just want to share an observation I made today. It’s about a 1987 FK-555, a 1994 Model M and an AEK2.

Some years ago the M hadn’t yellowed at all, the AEK2 only a little bit and the 555 a fair bit more. Now, the last three years or so the M and the 555 have been stowed inside two different cardboard boxes. Since then, I have been using only the AEK2, so it has been sitting on my desk all that time (I cover it with a cotton towel when I don’t use it). All three keyboards have been in the same room. Today, on the M the space bar still hasn’t yellowed. Looks like it isn’t made of ABS. The AEK2 looks the same as when I got it, so no further yellowing. But the 555 suddenly looks like yellow or green curry. It didn’t yellow those few years I used it before I switched to the AEK2. It yellowed after I stowed it away. I can’t measure the difference, but I trust my memory, and I have a photograph on which a bit of the 555 can be seen. It definitely wasn’t that yellow/greenish a few years back.

A bunch of other AEK2s and an AEK where way darker than the one mentioned above already when I got them. They can get really dark. More brown than curry, though.

For a moment I thought maybe the lack of light caused the yellowing. On the other hand, there a plastic bags and pieces of bubble wrap in the boxes. Maybe they emit something that makes ABS yellow. Maybe it’s the cardboard. Or maybe it’s just coincidence.

I don’t mind the 555’s heavy yellowing a lot, it wasn’t new when I found it. But boy, those blue Alps are gorgeous to type on! What a cultural loss they’re not being produced any more (same goes for oranges).


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21 Jun 2020, 19:22

There was a keyboard on ebay about a week ago that I thought had an interesting brown case and nice white keycaps. When I looked at the big pics in the ad, I realized it was just badly "yellowed."

I don't think that lack of light causes yellowing. Heat definitely does. UV does. I'll be somewhat amused if you say that you're a doctor and your "yellowed" 'boards are next to an X-ray machine or something. Are the keyboards in separate boxes or in just one big one?

I'm sure that there's a more comprehensive thread on this topic someplace here. I'll try looking for it in a bit. I'm interested. I also recently did some rest0bright-ing and I have some thoughts.

I've got to get my hands on some more Alps boards/keys. I'm really liking typing on this Matias keyboard, but I wouldn't mind something slightly heavier.

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21 Jun 2020, 19:31

While UV is often cited as the prime reason for yellowing of our beloved keyboards' plastics, heat is also another big culprit.

If keyboards were stored in an improper environment, ie without climate control, then heat and humidity could've played a part in its yellowing.

Also, I believe if there's already significant degradation to the ABS composition, especially if it's used bromine for fire resistance, it can't really be stopped. It's possible the 555 might've been retrorbrighted before. Retrobrighted plastics will become yellow again after a while, sometimes not that much time, admittedly.

My FK-555 which has been sitting in a box in my closet for years now is just fine, but it was never yellowed. Even when the air conditioner broke in the middle of summer once, it was still fine, though keyboards I had retrobrighted had reyellowed in that period of time.


21 Jun 2020, 20:19

The FK-555 and the M were in different boxes, but the M was alone in its box, the FK-555 shared one with an FK-2000 (2002?) and an M0118.

The FK-555 was never retrobrighted, that’s for shure. There is no X-ray machine, and the FK-555 didn’t get more heat or UV than the other boards. It just never seemed to continue yellowing, and now did quite a lot while in the box.

I wonder how long it takes ABS to yellow after it gets a dose of UV or anything.

@hellothere: I think the AEK2 is the most easy to find Alps board. It has later dampened switches, but with a bit of lube and optionally with click leaves they’re really nice. The AEK2 is a great chassis for own projects, I think. The case is solid and the PCB has some nice details: An additional key on the num pad I use as full stop over a Teensy (can be combined with shift!) and the Apple keys are switched parallel. It’s actually just one key. I use it as Alt Gr, so I have that on both sides. Very useful.

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