This is what the entry from the Zecchi site looks like to help in ordering: “ PRIMARY YELLOW. Chemical composition: Synthetic Organic Pigment (Monoazo). (Series: 2) .” Here is our best guess at the equivalent in Italian. This is from the Italian portion of the site: “ GIALLO PRIMARIO. Composizione chimica: Pigmento sintetico organico monoazoico. (Gruppo: 2).”