How do I change the color of my lava lamp?

I'm afraid that lava lamps are not made to be changed. They are sealed with a bottle-cap like lid that once opened may be very difficult to reclose. The stuff inside is an oily and toxic mixture of stuff which the manufacturer describes as "solidified globule of mineral oil, paraffin and a dye as well as paraffin wax or petroleum jell, preferably Ondina 17 with a light paraffin, carbon tetrachoride, a dye and the paraffin wax or petroleum jelly." I dropped a lava lamp once and it broke and was a terrible mess to clean up. I suppose you could try popping the lid off and adding food coloring.  more