Un-ground lumps. Gum Sandarac can be used for preparing paper and vellum for writing. It acts as an ink resist; holds the ink and prevents it from spreading, resulting in sharper letters and less likelihood of bleeding. To use wrap the lumps into a small muslin type bag to make a pounce. As the crystals are crushed the powder will come through the fabric and onto the paper. Gum Sandarac is non-toxic but the usual hygeine precautions should be observed.