Dry mounting is a popular way of sticking pictures completely to a board or other support (Foam boards, MDF and aluminium are also used). It uses a tissue coated with an adhesive that is applied in a press under heat and pressure. It is often used when aesthetically or practically a picture needs to be permanently flat. Because this process is almost impossible to reverse it is not generally suitable in conservation framing. Prints that have relief or plate marks should never be dry mounted, as these features will be lost.