Rubbermakers 21-10 is the most preferred by pyrotechnic manufacturers. It has the lowest acid content of the sulfurs and is -325 mesh powder. Insoluble in water, sparingly soluble in alcohol, soluble in carbon disulfide, benzene, ether and toluene. Now restricted under the injunction. Please see our home page under the heading 'please read this before ordering'. ATFE manufacturing permit required to purchase.