I love Stiffen Stuff but I get SO frustrated with it not wanting to spray after awhile. I have even tried putting it into another spray bottle to see if that would help, it didn't. I have ran it under hot water, doesn't help.
I keep a good stock of it, everytime Michaels has a 50% off coupon I get 10-12 bottles. Once one bottle starts going crappy on me I'll switch to another bottle & end up pouring the old bottle into the one that is working at the time as it runs low lol. Its the only "fix" I've come up with so far