be warned, it may run a bit TL;DR.we recently found a lava lamp i got my mother between '92 and '94, not old, but old enough that the lava had yellowed and the top had cracked, it does not have a…Continue
I tried to top off a lamp with fluid from a lamp that was made just three months earlier than the one I was trying to fix. The specific gravity of the liquid was not identical and the lamp quit working. I had to use pickling salt to readjust the gravity and it was quite a chore to get it right. In regard to sealing the lamp, you might try simply putting some plastic wrap over the top with a rubber band to secure it. That would be a quick temporary fix and probably a better seal than the one you are using. See ya!
Welcome to the Goo! Hope you make some nice friends and learn a lot about lava. You better get that evaporation under control by at least some temporary measure until you can get another cap. Hate to see another vintage lamp die an unnecessary death.