From 1200, there were changes in technique. Instead of working on a smooth layer of plaster, the painters now painted directly on a rougher, more uneven layer of plaster. Some elements were still painted affresco but a secco dominated. Contours were carved into the wet surface instead of painted, as before. Towards the end of the Middle Ages, the technique changed again: now the contours were typically drawn using charcoal or sometimes a pigment based on iron oxide. After the outlines had been made, the paints were applied, and lastly text (in the form of speech scrolls) and stenciled details and patterns were added. The palette of pigments expanded and changed as the Middle Ages progressed. Albertus Pictor, working at the end of the 15th and early 16th century, for example, used lead-tin-yellow, orpiment and Naples yellow in addition to pigments already mentioned. His workshop furthermore imported several pigments, probably from Germany. Albertus Pictor also used glazes on some details.
