An advice if you are trying to make "saltless" lamps: doing so increases wax-glassl stickyness, which will only go away if you just happen to dump the exact type and dose of anti-surfactant agents (pen ink seems to work, as does dish detergent, but especially with the latter it's easier to go overboard and turn all of the wax into a runny mess).
Also if you use wax that is not 100% paraffin, it also has an increased tendency to stick to walls. Using salt has the advantage that it virtually eliminates wall stickyness and so you can get away with much more rough wax mixtures, even in relatively small quantities.