Psiax. Attic black-figured amphora. ca. 525 BC. Museo Civico, Brescia, Italy. Greek vases often show thick matt brushstrokes usually white, yellow or purple in color- on the thin black varnish and the red ceramic background. A chemical study of such brushstrokes  revealed presence of beeswax and fatty acids, suggesting they were painted with water-soluble encaustic. Source: José Cuní and Jorge Cuní. Naturaleza de los colores fugitivos en la cerámica griega. Archivo Español de Arqueología, 65, 1992, 302-303.

Greek vases

Greek vases often show thick matt brushstrokes usually white, yellow or purple in color on the thin black varnish and the red ceramic beckground. A chemical study of such brushstrokes revealed presence of beeswax and fatty acids, suggesting they were painted with water-soluble encaustic *.
Attic black-figure amphora painted by Psiax. 510-505 BC. Museo di Santa Giulia, Brescia. White and purple encaustic applied cold on black varnish and red ceramic.

* José Cuní y Jorge Cuní. Naturaleza de los colores fugitivos en la cerámica griega. Archivo Español de Arqueología, 63, 1992, 34-35.