It’s damn annoying that some of the “disposable” pepper grinders (the kind made by spice manufacturers and sold at grocery stores) can’t be easily opened so they can be refilled and re-used when they are empty. I recently found myself with an empty disposable pepper grinder at the same time that I couldn’t locate my salt grinder. I thought I could wash it and fill it with sea salt, but … the grinder top is designed to be very difficult to remove.
Here’s the trick: Put the empty grinder container in a cup full of very hot water. Near boiling is good. A cup of water microwaved for a few minutes works fine. Soak the plastic top in this very hot water for several minutes. This makes the plastic just a bit more flexible, which should allow you to pull the plastic top off the glass jar. Just hold the glass jar in one hand and the plastic top in the other and pull them straight apart. Make sure everything is clean and completely dry and then you can re-fill it. To put the top back on, after you’ve refilled it with peppercorns or sea salt or whatever, just put the jar on the counter and press the top firmly onto it.