Yes, I understand, fiber only. I really love the bottles. If I decoded the boxes correctly, it looks like this was produced in 1974. Which explains it's sitting in a warehouse, for the last 40 years. I don't think, I have ever used anything like this. I remember a pro using Pakosol. The marketing people at Kodak said this even improved mounting, this, in a 1950s Popular Photography magazine. I'm wondering if the formalin was added to act as an antimicrobial? It would also act as a hardener, I presume. Definitely improved handling, and cracking, of over dried, single weight service photos. I will try it next summer, I don't want to vaporize this in the house, even with ventilation. I've breathed too much stuff as it is.
Mike