Retest After 5 Years
Some laboratories continue to use HSE/NPL Slides carrying ‘Retest after 5 years’ labels which have not been re-certified, nor are required to be by various accreditation authorities.
This re-testing requirement should apply to all HSE/NPL Slides because experience shows that the visibility of some HSE/NPL Slides deteriorate over time – probably because a synthetic resin, euparal, is used as a mountant which remains liquid or semi-liquid over years when captured between non-porous surfaces.
Pickford Slides are unlikely to require re-certification because they have been proven to be completely stable for more than 6 years by both subjective and sensitive objective visibility testing. This is because the mountant is a UV activated acrylic adhesive which remains hard and stable once activated during manufacture.
If shown to be necessary, re-certification of Pickford Slides will cost approximately $100 compared with more than $900 for the HSE/NPL Slide plus freight costs. The need for re-certification will be determined and communicated to owners by routine testing of a number of old Slides retained to confirm whether they maintain stable visibility or not over time.
