Model F (and possibly M) smoother-feeling keys = glossy keystems = most-used?

[quietobserver]

So on my recently-purchased 122-key Model F, which I haven't yet done much on beyond some rudimentary cleaning and some flossing, I noticed that some keys have a definite roughness when pressing them down, while some are a whole lot smoother.

Popping some of them out, I noticed that the ones that feel super-smooth have keystems that look... glossy, while the rough ones look matte.  What's interesting too, is that the keys in the main alphabet/number section of the keyboard are mostly very smooth, while the ones that I find especially rough come from the more obscure keys.  A lot of the keys are still in their original positions since I didn't pop them out yet, apart from the keys that I flossed (the main alphanumeric area, and the directional pad cluster - which I flossed separately so the key bottoms didn't get mixed between these two groups).

Could this mean that the most often used keys get smoothed out, gaining this glossy surface, while the less-used keys remain rougher and therefore feel rougher when pressed?

[jacobolus]

By keystem do you mean the part of the keycap that sticks down into the barrel, or do you mean the inside of the barrel itself?

Anyhow, it’s entirely plausible that use would wear the plastic smooth. I suspect adding some lubricant (e.g. Krytox GPL 201 grease) could also make a substantial improvement here.

I got a very bad condition Model F XT that had some pretty dirty barrels, and pressing the keys is very scratchy. I’m hoping that washing them carefully and possibly adding some lubricant will fix them up; hopefully the roughness isn’t from damage to the plastic itself.

[quietobserver]

Yes, I mean the part that sticks into the barrel.  Sorry I might not be too clear about what's what.

I'm thinking that if it is due to wear and the smoothness is directly related to the smoothness of the feel of the key, then that could also mean that that's the exact area that we should lube, right?

I also forgot to mention that swapping one that is smooth/glossy with one that is rough gives the expected result, i.e. the scratchiness/roughness seems to be linked to the keys, not the barrels.

[vivalarevolución]

Interesting observation.  I have noticed these differences, but I never looked too deeply into them.  After I do my usual full refurbishment of nearly every Model F that comes my way, these differences seem to go away.