Sellotape (UV damaged)

This treacle-coloured, crystalline object was found by our Director Zoe Laughlin on her family farm. Although completely warped and now totally dysfunctional as a result of photochemical degradation, it is still recognisably a roll of sellotape. Sellotape is the trademark of one British brand that makes pressure-sensitive sticky tape, but it is so commonly used to designate any transparent tape with an adhesive on one side that it has become the colloquial name for the material. This generic trademark has even made it into the Oxford English Dictionary, along with aspirin, cellophane and thermos. 

When functional, Sellotape is golden in colour, transparent when applied, sticky on one side, and easy to tear – characteristics that make it convenient and easy to use for purposes like bonding paper or card. The tape consists of a carrier layer made from a polypropylene film coated with a release agent on one side and a pressure-sensitive adhesive on the other. This glue contains several components like synthetic rubber, UV protector, antioxidants, synthetic resin, and pigmentation oils. In manufacturing, this adhesive mixture is applied hot to the plastic carrier layer stretched over large rollers and then rolled onto a cardboard tube and cut, ready to be packaged for distribution.

Henkel, the company that makes Sellotape, recommends a shelf life of 18 months at 20 degrees storage temperature. However, this roll could have been left in storage for much longer, possibly near a warm and sunny window. Exposure to sunlight, heat and the environment causes this material and its chemical properties to change. Polypropylene is particularly sensitive to degradation caused by UV radiation and thermo-oxidation: heat and oxygen react with the material, causing the shearing and cross-linking of polymers and the creation of carbonyl groups. All of this makes the material yellow and become brittle. Stabilisers and additives can be added to stop or slow down this degradation. Because we don’t know the exact materials used in the adhesive, it is difficult to evaluate the precise degradation and ageing mechanisms at play.

Since its introduction to the market in 1937, Sellotape’s usefulness has made it an indispensable addition to any stationery cupboard for decades. During World War II, it was widely used to seal ammunition boxes and help protect windowpanes from shattering due to bomb damage. Subsequent investment has seen various new tape products, including plant-based tape made with cellulose and naturally based glue.

Artists such as Finnish sculptor Inka Nieminen have used Sellotape to explore modern synthetic materials in their work. Haute Couture
(2004) uses layers of tape and clingfilm wound around in a mummification-like method to form life-sized transparent mannequins. Premature yellowing and ageing of the artworks caused concern for museum conservators sparking research into the degradation processes at play. Conservators can use analytical techniques like Fourier Transform Infrared Spectroscopy (FTIR) to compare the chemical components of materials when they are brand new against the chemical changes that occur when they age under different conditions. In the case of Nieminen’s Sellotape figures, faster ageing happened due to a lack of ventilation in storage, meaning that certain gases and chemicals released by her materials concentrated and sped up their decay. 

In museum contexts, understanding how materials change over time can allow conservators to treat them and ensure their long-term preservation. In contrast, the Materials Library’s degraded and dysfunctional Sellotape demonstrates the effects of unhindered degradation in action and reveals something interesting about the impact of time and the environment on these materials.