Sweetening or spices can be added if you choose. Begin by adding only one to two spoons of sweetener since many totally ripe fruits need nothing more. If you are making leathers from light colored fruits such as apples or peaches, heat to almost boiling before beginning to dry. This will help prevent browning. Fruits can also be combined.
Some good combinations are cherries and rhubarb and strawberries and rhubarb.
All of the small berries like raspberries, blackberries, and mulberries go well together. Pour the puree in and spread evenly by tilting the tray or sheet back and forth to spread it out. The thinner and more consistent the thickness, the better and quicker it will dry. One-eighth of an inch thick works well. If it is too thick it may spoil before drying, and if not consistent it will not dry evenly.