Thanks for the replies. I will look for the high percentage isopropyl. I have only recently acquired the drying mark problem, and I'm sure I will be able to lose it again by tightening up final wash procedures. It sounds like a pharmacy is the place to try, although Boots, which is a very large chain in the UK, didn't have any. A smaller, local store may be a better bet. The blue stuff has been put away out of reach! Alex