Thanks for the responses. I’ll discuss them one at a time:
Linda asks: “Isn’t the problem with the PDMS that gets foggy – not the vat itself? It seems that you would still be replacing the pdms just as often.”
Yes, fogging is certainly one of the problems that the glass vat doesn’t solve. But the PDMS seems to adhere better to the glass, so the failure mode where the rubber peels off of the vat bottom due to a print sticking to it should be less common. And recoating should be easier, since one can remove the old PDMS layer without accidentally scratching the vat bottom.
“Do you think the glass tray has a higher level of optical clarity compared to the plastic used by FormLabs?”
I do, although I have no way of quantifying that. I can say that it’s less likely to get fatally scratched or smudged, which can happen easily to the bottom surface of the plastic vat, and cleaning it is much easier.
"Using regular glass on the bottom is a bad idea. Glass blocks UV light on some level. You need to use optical quality glass or similar material that doesn’t block UV light.
How are your prints coming out?"
That’s a good point, and it’s the main reason why, after some research, I went with (expensive) borosilicate glass instead of cheap window glass, which is more fragile as well. I still wasn’t sure it would work, but I’ve done 3 prints so far and they all came out perfectly, which hadn’t been the case heretofore. The lack of “floaters” seems to have made a big difference - I noticed them in my tank recently after a single print made with a brand-new plastic vat and new resin. So far, after 3 prints with the glass vat, there are no globs of semi-cured resin cluttering up the tank and sticking to the prints. That’s something I wasn’t expecting, but I certainly don’t miss them.