Photo: Brenda Anderson (flickr)
Have you ever noticed this? When you quickly pull a piece of transparent tape off its roll, it tends to do a good job of staying transparent.
However, if you pull the tape off slowly, or if you pause for a moment while you pull it, it can leave behind opaque white lines on the tape. What’s going on?
Those little white lines, and whether or not they form, are a result of the chemical properties of the adhesive layer.
When you pull your tape off the roll slowly, or if you begin pulling after a pause, the sticky adhesive pulls out into long, drawn-out strands. These eventually break and fall back onto the tape. You can see these gluey strands if you carefully watch the tape unroll with a magnifying glass. When the strands finally break, they leave quite a microscopic mess. This can disrupt the way light passes through the tape, leaving behind an opaque white line.
When you pull the tape more rapidly, the adhesive chemical responds in a very different way. There isn’t time to stretch into long, sticky strands, so the adhesive breaks away much more cleanly. Light passes through this clean, uniform surface more easily, making the tape transparent.