Let sit for a mintue so as to let the heat penetrate, then, holding the
print on the bottom of the tray (smooth bottom helps here) slightly
"rough" the corner with your finger by pulling your index finger down
over the pointed corner. In a few strokes, the backing ought to start to
seperate.
If you are a nervous person and bit your fingernatils it may be hard to
graps, if so, use a pair of tweezers, otherwise, grasp the corner …
still under the warm water … and pul slowly the two layera apart. It
really goes swiftly if you do this.
I have tried, fruitlessly, and, as Ms. S notably notes, 'abjectly'
failed to get the twain to unmeet.
You can easily learn this technique in moments and it is easy.
Jack Fulton