The lava-lamp wax sinks on cooling, so the surrounding liquid must have a density a little less than 0.9. Ordinary alcohol (ethanol) has a density of about 0.8, and a 40-50 per cent aqueous solution would have a density that could be adjusted to just below that of paraffin wax. The solid wax would then sink.
Now you know what to pack for Bora Bora you can get started. When you are done, weigh your bags. Luggage allowance for Air Tahiti inter-island flights is 20 kg/45 lb per person and strictly enforced (due to plane size). Divers may have 5kg extra. Carry on hand luggage is 3 kg/6.6lb. See more absolutely 'must know' info about flying to Bora Bora to ensure smooth Bora Bora travel.
The international weight limit for carry-on bags and personal items is 40 pounds. This includes the bag and all its contents. It is a good idea to weigh your carry-on bag before leaving home. If it is within 3 pounds of the maximum, remove some items. Airline scales will be more accurate than your home scale.