So many times. A woman sat on the stairs (it's usually a woman- men can't be bothered), up to her neck in scrapers and Nitromors burns. I might be working there for weeks. She's always there. scraping. It's a laborious job. As far as I know, that product is as good as anything else. Works on the "poultice" principle. Paint it on ... wrap up in polythene ... wait for...