After having bought a defective lava lamp (the story of which is amply detailed in the problems subforum), I decided to try the homebrew approach to Lava Lamp appreciation...I'd keep the globe, base and coil and replace the FUBAR liquid and wax of the original.
All in all, I must have been pretty lucky: in less than 36 hours worth of trials, on and off, I managed to get my first working, flowing lava lamp :-)
It's white wax in a greenish/blueish fluid, giving it a ghostly feeling, plus it has a small " eye" in the wax that lasted several cycles, so I decided to call it "Casper" after the friendly ghost.
What I used:
LIDL's blue tealight candles (well...the blue tint was minimal, plus I mixed in a solid pink one).
Unispec electric motor and machinery cleaner as a perc source. Very pure, as it proved.
Iodized table salt (I know it's a no-no, but so far it works OK...)
Reused the globe, coil and base from an existing lava lamp with bad fluid and wax. Had to fit with a 30W reflector bulb (instead of 25 W) to get it to warm up sufficiently, though, but it seems unnecessary after a while.
My Mk I goo turned out not to be dense enough and turned transparent and feather-light upon heating. So I just took it out, warmed it up and added another finger-worth quantity of perc for the Mk II goo.
Now the goo stayed down...a bit too much.
After experimenting with the fluid, a mixture of 3 parts water, 1 part windshield cleaner, 4 teaspoons of (iodized, oh woes!) kitchen salt did the trick. Of course, a lot of extra perc must have leeched out during the adjustments, but now it seems perfect, so perhaps over-specifying the goo wasn't such a bad idea...
And now it happily flows....but I probably must add some soap and remove some wax because the bubbles are very large and there's probably too much wax in it.
But, I take, this wasn't too bad for a complete rookie :-)