What are the differences between steel-backed and polyester-backed photopolymer plates?
Both types of plates have same printing surfaces made from photopolymer. Polyester-backed plates however are traditionally used in rotary letterpress and have many advantages for those who print on cylinder and platen presses. They’re easier to handle and have better registration systems than steel-backed plates (which in the past have commonly been used in flatbed letterpress printing). Steel-backed plates are rigid and don’t bend well. This inflexibility causes plates to kink and warp so that their corners work up on the press. In addition, you must use metal shears to trim these plates, which leave the plates’ with sharp edges. To print on steel-backed plates, you need the rather imperfect magnetic base to hold the plates at type-high. Magnets effectively hold a plate from peeling but cannot always hold a plate from moving side to side. The cylinder or rollers of a press can move steel-backed plates out of register, causing plate creep. In contrast, polyester-backed plates are very
