Again at lunch I was annoyed by saltcellars having tops clogged by moisture, and this is a very dry place. They ought to make saltcellars with plastic caps to keep moisture out. I used to have some that had a very small rubber stopper in bottom that was opened by pressing a button on top. At least once a month I have to put salt on a plate and give it a short burst in the microwave to dry it while cap was washed and dried.
You didn't say how big the Zild saltcellars are, but the salt boxes had to be big enough to hold at least ten pounds of salt, to have room for a couple cups of yeast culture, and hold enough heat to do the job.