Sumi is the Japanese word for a form of activated charcoal also called Bokuju that is used domestically in a wide range of applications. It is produced by firing certain species of oak or bamboo in clay kilns at temperatures of up to 1000 degrees celsius for as long as ten days. Unlike the ordinary charcoal used at a barbecue, sumi retains the natural shape of the raw wood while becoming harder and denser. After being removed from the kiln, washed and properly prepared, Sumi has the appearance and feel of polished stone. Liquid Sumi ink is made from high-quality vegetable oil soot. Both economical and convenient, it eliminates the need for grinding. Black ink, Non-Toxic and available in 6 oz, 12 oz and 60 oz sizes.