If possible go for the glyoxal version, the formalin is pretty bad for you. But if you are on a tight deadline, it'd be quicker to acquire some formalin because it can be found locally. If you have chrome alum around you can use PE's recomendations as well. My poorly communicated point was that for a subbing layer, knox gelatin seems to be sufficient in place of photo-grade gelatin.

Yes you can substitute the tile for paper in the above post. Haha