Think I saw program once lady scientist was manufacturing her own trainers, the foam she used came in a two part solution when doing tests to get correct foam density she just added more of one than the other that creates bubbles in the foam making it softer, think if I was making a saddle I would have a soft top layer then and rest much firmer, needs to be able support sit bones of reasonably heavy rider and recesses to avoid pressure on nerves and other sensitive areas, i cant remember name of chemicals used but packing looked like it was an available product
Well I looked it up and you are correct :wink: density can only be controlled chemically, and the part b is in fact a catalyst for the polimerization, the time this takes is controlled by the catalyst and is critical, if polymerzation occurs faster than gas generation the foam shrinks when it cools after the initial exothermic reaction good luck with your seat