Label residue

In detail

The adhesive on a self-adhesive label is a pressure-sensitive polymer, formulated to remain permanently tacky rather than to cure. That is the whole of its behaviour: it never sets, so it never becomes brittle enough to flake off, and it collects airborne dust continuously until the sticky patch is a grey one. It also explains why picking at it works so badly. The adhesive's cohesion is low and its adhesion to the surface is high, so it tears rather than lifting, and each pass leaves a thinner film over a wider area. Three approaches address it, and each works by a different mechanism. Heat softens the polymer and reduces its cohesion further, which is why a warm cloth laid over a label for a minute lets the paper lift whole. A solvent dissolves it, which is fast and is where the material risk sits — acetone dissolves resins and plastics and will craze a container, white spirit attacks plastic, rubber and coatings, and either will remove printing. And an oil works more gently, swelling the adhesive so it can be rolled off, leaving a greasy film to wash away. On glass the trade caution stands: razor blades and metal scrapers are not part of routine cleaning.

Why

• Label residue is explained by Adhesion and cohesion
• Label residue is explained by Surface roughness