The IBM keyboards used for the PC, AT, and PS/2 used a "buckling spring" mechanism that is not mechanical, as later models use a membrane.

I am typing this on a Model M that is dated "22JJUL88" - I do all of my important typing on these keyboards.

https://en.wikipedia.org/wiki/Model_M_keyboard

I’m fairly certain that Model F and M keyboards are considered mechanical.

It’s not a precise category. But I’d even go so far as to say they are the type specimens for mechanical keyboards.

Yes, most products in the category use Cherry-type switches, but Topres are definitely considered mechanicals and they combine a rubber dome and a spring.

Literally all keyboards are mechanical, what’s the alternative? Organic?

The term is used figuratively, not literally.

Buckling spring keyboards count, rubber-dome and scissors don't. There's no overarching principle here, if there is, it's how they feel under your fingers.

Optical or touch.

Te only thing that prevents me from switching to a mechanical keyboard is I care about my coworkers ability to concentrate.

Cherry MX Browns are reasonably quiet. My local Micro Center has a tester keyboard with a variety of switches that you can try. If you look outside the limited options there, you can find huge selections of mechanical switches that are only slightly louder than membranes. You’re looking for linear or tactile switches and you can find a pretty complete list at https://deskthority.net/wiki/Main_Page in the “Keyboard Switches” section. You can even mod louder switches with O-rings to dampen the noise.

I agree, MX Brown are silent enough to not get notice.

I guess it's a positive side effect of open spaces: there is so much noise around from phone calls and co-workers discussing that it doesn't make any difference.

More seriously, I've a Ducky keyboard with MX Browns (and it's also a weird one with MX Blues (the noisier ones) for the arrows and page UP/DOWN), and I never got any remark for that.

The only story I've heard from colleagues complaining about keystroke noises was for a friend that has a really heavy typing (to the point of cracking the key caps), and even in this case, rubber O-rings did the trick to dampened the noise enough.

Then get some medium stiffness linear switches. Near silent unless you bottom out, and the added stiffness helps with that.

> sometimes older really is higher quality

You can apply this successfully to espresso machines, coffee grinders, furniture and many tools (gardening, woodworking etc). The difficult part is finding them as often you need them immediately.

For me it's stereo receivers/turntables and cast iron pans. Vintage Le Creusets look incredible and they feel so good to handle.