Easy tear masking tape

An elongate strip of normally tacky and pressure-sensitive adhesive tape wound convolutely upon itself about a core to form a roll, said tape having particular utility for use as a finger-tearable masking tape, comprsing in combination an approximately 55-65% crystalline isotatic polypropylene film backing having a 4-ply impact strength of about 1.8-3 kg-cm, said backing having an overall thickness on the order of 75-115 micrometers with one smooth side and one rough side, a layer of normally tacky and pressure-sensitive adhesive firmly adherently bonded to said smooth side, said rough side having closely spaced randomly disposed valleys extending substantially at right angles to the lateral edges of said tape, said valleys being separated by ridges and having a depth of greater than 50% to about 70% of the overall thickness, so that the tape has the general appearance of creped paper masking tape but differs in that it has an Elmendorf tear strength of about 30-50 grams and is consistently readily finger-tearable in a straight line along one of the valleys at right angles to its lateral edges, said tape, when subjected to a stretching force parallel to its length in excess of the yield strength of the film backing, differing from masking tape having a smooth-surfaced polypropylene film backing in that it elongates throughout its length without reducing significantly in width.