I am going to be trying to soak my first card today. Won several at Sterling auction that have a piece of paper attached to the back. I will start with this one and will gradually work my way up to a Matty/Myers one that is otherwise in spectacular shape. Here are the before photos of front and back. To me, it does not look like the entire card needs to be submerged and I am going to try the methods used by the original poster in this thread. I will take some "after" photos when all is said and done.
Say a prayer. I'm going in!
Tom C