Screens need to be safe for contact with food. The best screens are stainless steel, teflon-coated fiberglass and plastic. This is galvanized metal cloth that is coated with cadmium or zinc. These metals can oxidize, leaving harmful residues on the food. Also avoid copper and aluminum screening.
Copper destroys vitamin C and increases oxidation.
Aluminum tends to discolor and corrode. Because birds and insects are attracted to dried fruits, two screens are best for drying food. One screen acts as a shelf and the other as a protective cover. Cheesecloth could also be used to cover the food. Solar drying uses the sun as the heat source, but a specially designed dehydrator increases the temperature and air current to speed up the drying time.