I'm kind of amazed at all the intricacies of technique described whenever a thread like this is started. It's really very, very simple:
- Fill bowl with water
- Drop in card and it will soak. You don't have to touch it
- Check after about 5 minutes. Is stuff loose, or does it come completely off? No-leave; Yes-remove. Use your own judgement - you might have to leave it for 2-3 hours in severe cases
- Once you can 'rub' off material easily with your fingers, remove and pat off excess water using typing paper. Repeat until reasonably dry.
- Place between two sheets of typing paper and insert into a big book
- Stack lots of additional big books on top. Leave for as long as you can stand - 2 days is always enough
It really is as simple as I have described - I've done it countless times.