Masking Tape: Crepe Paper and an Adhesive That Never Dries

Drew's invention relates to "pressure energizable adhesives, adhesive sheets or coatings, preferably water insoluble and normally non-drying." He describes it for the paint shop: "in finishing automobile bodies with lacquers, paints or the like of a plurality of colors, difficulty is found in limiting the application owing to the diffusion of the spray"; to get "a clear and cleancut line of demarcation between several colors", masks of adhesive tape had been used. Ordinary gummed paper tape, wetted to stick, "adheres so tenaciously that to remove the same requires softening of the adhesive material with large quantities of water", and the soaked paper tears. Cloth-backed tape costs more, and "the woven fabric is distensible to an extent which will make its edges irregular and unsuitable for stripping". His material may be applied "to paper which is toweled or crimped or otherwise shaped to present a surface other than flat and which has an extensibility beyond that of the flat paper web."

Paint a piece of plywood one colour of acrylic and let it dry fully. Lay masking tape along a straight line and round a curve drawn with the compass; note the smallest radius the tape follows without wrinkling or tearing. Press the edges down firmly. Paint the second colour over the edge of the tape. Pull the tape while the paint is still slightly soft, back over itself at a low angle, and compare with a strip pulled straight up. Look at the line with a hand lens: a clean line, a bleed under the edge, or lifted base paint.

**Richard Gurley Drew** filed US 1,760,820 on 28 May 1928 as a continuation in part of an application of 11 April 1927, assigned to **Minnesota Mining & Manufacturing Company**; it was granted on 27 May 1930. **Honest limits.** The stretch limits and adhesive energy in the notebook are assumed examples; the peel formula ignores the backing's stiffness.