So I read an article on Oozing Goo the other day,
and decided on a whim to change the color of my 2001 32oz USA Lava Lite Black Starship Lava Lamp from clear to red. Just like the article said, I pried the tabs up one by one, my heart pounding the whole time. I had bought a vile of Kroger brand Red no.40 food coloring the day before, and added 1cc of dye to my Lava Vase.
However, I took the extra precaution of permanently re-sealing the cap by painting a ring of acrylic nail fortifier inside the cap and on the lip of the bottle. Later, after re-crimping the cap back onto the bottle, I applied a liberal amount of the stuff under the rim of the cap, further ensuring that my lamp will never, ever leak.
After waiting a whole day for the nail polish to set, I plugged it in, and whola, it is beautiful. BTW, the lava really is a true black; it looks purple because my webcam is crap.