Howdy. An alternative that may be worth trying before any sprays or chemicals is what I know as "airbriting" or "sunbrighting", which is literally just leaving the plastic out to sunbake for an extended period.
I do not have any experience with "sunbrighting" a M100 but in general I have had very good success in restoring the color of all but the most stubborn yellowed plastics by just baking the plastic in the sun for several days. For example, this last month it took me ~8 sunny cloudless days to complete the de-yellowing of a moderately-heavily yellowed compaq keyboard (including keycaps), though I could see results after the first day or two. In a few projects where "sunbrighting" has not completed the job for me it has at least reduced the yellowing substantially. I have the benefit of the Aussie Sun but it's not that much different to other parts of the world. The technique was recently covered on the Retro Recipes youtube channel at https://www.youtube.com/watch?v=8P1OVj0IcqY In that video there is also some mention of using LED lights to help prevent the yellowing from returning, which I believe may apply to both retrobriting and sunbrighting techniques. Incidentally, the room in which I keep my gear does happen to have LED lights and I have not seen the yellowing return in any of my items - though I have only been dealing with this for a short while. I've recently acquired an NEC 8201A and have been lurking here accumulating info that will be of help when I get around to studying it, but thought I should mention the possibility of "airbrighting" in case it is of use to you or anyone in the same situation. Regards, Ben On Tue, Oct 13, 2020 at 10:13 PM Michael Kohne <mhko...@kohne.org> wrote: > I've got an M100 with a severely yellowed upper shell, and I'm > wondering what remediation possibilities I have. > > I've heard of retrobrite, but I've also heard that it can make > plastics more brittle. For something that's a portable computer, > brittle (even if only slightly more than original) sounds like a bad > idea. > > Had anyone ever tried painting one of these shells? Are there paints > that would hold up to actual use? It'd be like painting the case on a > keyboard, and I'd worry that it was going to chip or rub off very > quickly. > > I poked around the mechanical keyboard community and found references > to using Krylon's Fusion paints, anyone have any experience with them? > > Also, does anyone know what kind of plastic the M100 shell is? I'd > like to find some similar plastics to experiment with before I risk an > M100 shell. > > -- > Michael Kohne > mhko...@kohne.org > > Anything real you do that's important will be scary. Having kids. > Getting married. Donating a kidney. Writing a book. Do it anyway. - > Neil Gaiman >