Yeah agreed. I don't think it would make sense for a monochrome CRT to use a shadow mask. That's something color CRT's use and dot pitch is only relevant to those. There has to be separate phosphor for each color, so that's why you have a limit on how many you can have and still keep them separate. Hence the dot pitch.

I don't have exact knowledge of how monochrome CRTs work. I believe they just spray phosphor onto a screen inside the CRT and the cathode only needs to really scan across with varying degrees of intensity to produce different shades of grey. How much detail you can have is mainly dependent on how well you can focus the electron beam striking the phosphors. That's my over simplified view on how it works.

Monochrome CRTs are a much simpler design then color ones so resolution is mostly governed by the electronics driving the CRT and not so much the CRT itself. Barring possible voltage limitations of the CRT itself, I'd imagine if you had capable logic driving the CRT, you could probably drive much higher resolutions on a compact mac CRT then what the original hardware provided. You're not limited to a dot pitch like the color CRTs.

Also, you happen to know what the specific monitor it was that could be used as a CRT donor for a compact mac? Might be something I could consider later as my Macintosh SE does have burn in. (I wouldn't say it's really bad, but it's noticeable. Only thing I really see is the faint outline of the desktop. Slightly more prominent is burn in of the menu bar.

If it ends up being cheaper then buying a replacement CRT that came from a compact mac, that's what I'll probably go with if I'm sure I'm getting the right thing.