Dab A Coating Of Petroleum Jelly On Glue Caps To Keep Them From Sticking Thorin Klosowski Jun 16, 2016, 2:00pm 0 If you have any type of strong adhesive, there's a good change the cap's stuck on there tight because you didn't bother to clean off the nozzle the last time you used it. Rockler reminds us that a little petroleum jelly can solve this problem.