You will find that most chainsaw trouser manufacturers won't state information on the washing of their garments, SIPs' (trade) rather than professional can be machine washed, problems arise when you tumble dry, hanging trousers causes the fibers to pull. Any advice in that area is best sought from David Cooper-Holmes at Workware.
Ste - highly likely wouldn't have been covered within your chainsaw training as it is not part of the NPTC schedule of assessment, you have to state what PPE a chainsaw opertator shoudl be wearing but that is it. I tend to take my candidates thorugh different PPE, types, makes, cleaning also the differences in type A/C, Chaps and what chaps are acceptable. Depends on your training provider - Consistency of information what's that then?
Stretch air are good, but so are the SIPs', the new freedom range are also worth a try. Type A.