I got the canada balsam and xylene. The canada balsam is the synthetic variety but also in xylene as used for microscopy. Rather thick stuff, almost like liquid honey.

I tried to glue a (polyester) filter between 2 old 6x6 slide glasses. Was a terrible mess. I think the balsam is too thick. But what is about the right viscosity? Can you thin it too much? (probably if too much xylene it will set to quick)