I am looking to increase the strength of my green sand. I had some success adding Bentonite but I heard "Sea Coal" will help. I got a bag of coal at the farm supply store and ground it up in a blender. Anybody know if this is fine enough? Or of any methods of getting it finer.
Someone please correct me if I'm wrong but I've always understood that sea coal does not contribute to green strength, it's primarily there to improve surface finish especially when used with cast iron.
