The problem was solved shortly after that workshop and the blades were reworked to meet the 1 mil specification. Sorry, I thought I had posted that. The film and plate coaters did not have the problem due to size. I showed one prototype of each (film and plate) coater at the workshop you attended.

Film and plate coaters are identical except for 2 things. The plate coaters are narrower in order to fit one plate, but the film coaters are 1/4" over width to allow for sheet film widths plus selvedge. And, the plate coaters allow the doctor blade to sit as high as the thickness of the plate + the desired undercut. So, a film coater will allow 2 mil - 20 mil undercut but a plate coater will allow that plus the thickness of a glass plate.

I coat 3 - 4 4x5 plates at one time using a plate coater. I've shown the coater and the results here and I believe in the video on APUG.