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Impervious to the harshest of conditions and providing vitally important information and visibility, Sessions of York has supplied small white self-adhesive UV sensor labels to a leading government sponsored research institute for labelling phials of biological substances, such as blood, hormones and vaccines. The institute is active in valuable research and development on behalf of the World Health Organisation and works on and supplies the biological matter used in medicines. Therefore accurate, clearly identifiable and robust labelling is essential.

The labels, made from Thermal Transfer Polyester, were chosen after a variety of rigorous tests were undertaken to test their suitability to the particularly hostile environments in the laboratory. The labels are applied to the glass phials by a Sessions labelling unit before the product is filled and so need to withstand both steam sterilisation - through the autoclaving process - as well as freeze-drying. After filling, a cold vacuum is applied to the phials which are then finally exposed to high freeze temperatures between -20ºC and -30ºC.

The surface of the plain label is coated with a fluorescing varnish strip by Sessions in order for the imbedded ultraviolet pigment to act as a trigger in the production line. The Polyester film works perfectly for this application as is does not have the optical qualities or bleaching agents inherent in paper, allowing the UV band to be recognised instantly by a labelling machine, eliminating disruptions in the production line.

A Sessions’ Basic labeller with top attachment is used for this particular application and is fitted with a special label sensor which rejects any phial without a label. In addition, the labels are compatible with foil as they are coded prior to application via a thermal transfer printer.