In my experience, it doesn’t matter if I insert a nail or a screw into the nozzle of a partially used tube of caulk. The caulk will still coagulate into a frustrating lump that renders the tube useless. To remove the hardened caulk, I use my utility knife to slit the entire length of the nozzle. Then I pry out the caulk lump, and tape the nozzle back together with electrician’s tape.
Nancy Hart Serum, Oakland, CA