I've had surprisingly good results using BBQ lighting fluid (check it's naphtha first!) but it's best to recrystallise with something cleaner afterwards.
OTC lime can be found in aquarium stores as "Kalkwasser" - why the German name, I'm not entirely sure. Many general household stores carry white spirit but the same caveat applies as the BBQ lighting fluid - especially as nowadays there's this crappy "environment friendlier" white spirit replacement which is heavily cut with water and detergent.
Artists' supply stores (or, I should say, shops) stock low-odour white spirit which is pretty good albeit expensive.
If you're a fan of the DIY approach, it's reasonably easy to make your own calcium hydroxide by heating calcium carbonate (chalk or limestone, but not blackboard chalk) to about 1300°C.
Best of luck