I've been in Public Works for 25 years and I am a skeptic. We have tried countless graffiti removers with many promises that they would work. None did a complete job. We recently had graffiti applied to large cast concrete blocks. We tried 4 different products including Zip Strip and nothing touched the graffiti. Your salesman, Roger, came by with Elephant Snot.® I almost blew him off, but decided to have him try. The Elephant Snot® completely removed the graffiti. Look at my face --- can you see the black feathers around my mouth.