Gloves are a very good form of protection against chemical hazards, however when they fail this almost always leads to danger. It is important for anyone responsible for specifying gloves to understand the complex reasons gloves work and stop working.
There are four main ways gloves can fail to protect. Firstly is misuse, including using the wrong gloves, using them incorrectly, particularly in putting on and removing, using them for too long and not storing them correctly, particularly when they will be reused. Secondly is physical damage to the glove, or selecting the wrong performance level. Third is destruction of the glove by chemicals. And finally permeation, this is the transmission of a chemical through the glove material at a molecular level.
Permeation is difficult to determine, compared to the other three factors. To test for permeation the European standard EN374-3 divides gloves into six classes, from Class 1 for a breakthrough time of more than 10 minutes to Class 6 for more than 480 minutes – the breakthrough time is the measurement between initial contact of the chemical on the outside of the glove material and its analytical detection on the other side.
Glove manufacturers publish tables which list the permeation time for a certain chemical by each of their glove types. However these times are achieved in a laboratory test and will have little in common with what will happen when the gloves are used at work. It must be considered that permeation time can be lengthened by factors such as frequent glove washing, low temperature, weaker chemical mixtures and incomplete or intermittent contact with the chemical. The time can also be shortened by flexing and stretching of the glove, high temperatures, abrasion, ageing and degradation. For more information please see here.