Problem Solved

Jim Patterson, president, Static Clean International

Problem—In many web press applications, film substrates—especially label stock—have to be corona treated in order for ink to bond to the substrate. The corona treatment process, which uses high voltage to bombard the stock, can create imbedded charges in the film which are difficult to eliminate. These charges are sometimes called polarized charges or electrets and are difficult to detect using traditional handheld static meters. Blocking on film being wound on a take-up roll and difficulty feeding once the material is sheeted are a couple of well-known problems resulting from this condition.