All Canadian stamps are soakable in hot (70 C) water. The water activated ones peel off after about 1 minute, the self-sticks take a little longer. I process them in batches of 25 stamps at a time. It takes less than 10 minutes to complete the soaking. Many self-sticks have a kind of gum that converts to what I call “rubber cement gum” in the hot water and any adhering gum can be rolled off between thumb and forefinger, just like you used to peel the rubber cement off your fingers (back in those days, if any of you remember them!).
I save, as cut squares, only those stamps which have a CLEAR postal cancellation on them. I use hinges to put them on quadrilled stamp pages and enter pertinent information below the stamp.