Discontinued This easy-to-use, non-toxic gel can be applied to any surface and is virtually invisible! When contact is made it begins to dye the skin BRIGHT BLUE immediately. Even if wiped off quickly it is very tough to remove. Can only be seen under UV/Blacklight. May remain on skin for several days. 1 ounce. Instructions included. MSDS included. Follow all MSDS precautions when using this or any other products. Additional Home Protection Advice! Order online, fax or by giving us a call!