UART Sanded Pastel Paper P-102892 9-Inch/12-Inch No.400 Grade Mounted Board, 3-Pack Our computer controlled electrostatic coating process results in a consistent grain application Uart pastel paper is ph neutral and acid free It can accept under painting using a wide variety of medias such as water, oil, mineral spirits, turpenoid and alcohol After the under painting process, the tooth still holds many layers of pastel and the grain will remain affixed to the paper Uart is available in seven grades from 240 to 845