Is there a way to use only part of a can of urethane insulating foam
spray, and save the rest to use later? I find if you don't use it all
right away the nozzle and dispenser tube permanently clog.


Do like I do and take extra ones from the existing cans at the Borg. That
leaves the can unsaleable and it gets returned to the supplier.

If they can't make a product that will allow you to use more than 20%, they
deserve returns.