What was encaustic
In this paragraph, Pliny does not say anything suggesting that the encaustic applied with a brush was different from the encaustic applied with a spatula; that is, he establishes no difference between methods by the tool used. The index of this chapter refers to artists that painted "with encaustic spatula or brush" (Plin. N.H. 35, 39-41). Pliny also tells of specific artists who painted with encaustic on ivory, or who painted with a spatula, but without mentioning the type of support used.