Letters: June 2024

Blooming in industry

I read your article on Barbie’s conservation with interest. It shows the dilemma of plastics.

While the article reads like a good analytical chemistry detective story, it makes me wonder at which point the researchers sought the help of industry. The appearance of a wax-like exudate on the surface of flexible PVC articles over time is well known and referred to as blooming. The factors controlling blooming have been available in open literature for decades.

While stearic acid is widely used as a lubricant, Barbie dolls are produced from plastisols: liquid dispersions of PVC resins and other solid ingredients in liquid plasticiser. The resins required for these formulations are manufactured by emulsion polymerisation. The precipitation of low levels of residual emulsifier over time is frequently behind blooming. This is the case with stearyl alcohol.