Carnauba is a non-toxic hard yellowish to brownish wax from leaves of the carnauba palm used in food, cosmetics, automobile and furniture wax, and as discussed here- to temper encaustic paint (use no more than 5%). Keep in mind that ratios vary with the added use of damar resin.
Carnauba wax has a very high melting point of 180-187 °F (82-86 °C). It is extremely hard and nearly insoluble. It is also a renewable resources.
For further information read Temperatures (Melting and Flash Point) and How to Make Encaustic Medium and Paint.
