More on Keycap Shine

Another follow-up post, this one regarding my post yesterday regarding how “greasy”-looking keyboard keys are not, in fact, in need of cleaning, but instead are worn away because they’re made from soft ABS plastic, not hard PBT plastic. DF reader Brian Barefoot Burns wrote me:

Hey, John. Even on keyboards made with PBT key caps, the space bars are usually still made with ABS. The reason is that PBT shrinks more than ABS does during the manufacturing process. For the smaller key caps, this shrinkage can be managed, but it’s so significant on large keys like the spacebar, that even the IBM Model M and similar keyboards that used PBT still had ABS spacebars.

That explains both the visible erosion and yellowing of the space bars on my Apple Extended Keyboard II’s.

Also, there was a discussion on ATP episode 562 back in November about keycap wear, and one of their listeners pointed out that ABS can be made transparent to let backlighting shine through, but PBT cannot. You can make PBT keycaps with clear (ABS-filled) cut-outs for the letters, but that would undoubtedly add cost and complexity. My beloved Apple Extended Keyboard II has no backlighting at all. It’s quite possible that this entirely explains why Apple sticks with ABS despite the shiny-when-worn factor.

It’s also the case that some people’s natural skin oil wears away ABS plastic more than others. That same ATP episode’s show notes link to this extreme (and extremely gross) example. Jiminy. (Poor U, the least-typed vowel.)

★ Thursday, 25 April 2024