I have been able to print cyanotype images on glass using several type of Polyvinyl Alcohol(PVOH). I have used the Poval R-1130 as a base subbing which provides tenacious adhesion to glass and a much more suitable interface for other PVOH grades that do not have silane in them. Once the intial R-1130 is dry and hard I apply another coating of Kuraray Mowiol 4-88, boric acid, and a fumed alpha alumina dispersion. This second coating readily accepts and holds a cyanotype coating much better than a plain PVOH coating.
I am still working on the formulation that provides a consistent reliable print, some issues of very fine cracking/crazing of the coating occurs which I am hoping to fix and tweaking ration of the mixture to best optimize. Also working out ways to get a clean consistent coating which is necessary for consistency in image density.