I'd use auto paint stripper. Available from auto paint shops. A litre should do it. It's stronger and quicker. Just don't let it dry.I'd also use this type of scraper
http://cgi.ebay.com.au/PAINT-BRUSH-B...item43a118b3f5 available from bunnings. Follow the instructions in the can. Don't use hot water to clean the paint stripper of the tube only cold water. Wear protective gear, glasses,gloves etc.
Cristian