Hodges wrote and article I beloved in the GNSI Newsletter. Perhaps there is something in archives. A claycoat surface provides a good tooth. It will seem light compared to graphite but will oxidize depending on whether it is set or not. Might do a search online for historical techniques as well. Best, Deb Sent from Yahoo! Mail on Android Need to leave or subscribe to the Sciart-L listserv? Follow the instructions at http://www.gnsi.org/resources/reviews/gnsi-sciart-l-listserv