Sprayways new improved two layer Hydro / Dry fabric is guaranteed to keep you dry and will hold back a column of water 20 metres high without leaking i.e. the Hydrostatic head is 20,000 mm. There is a breathability rating or MVTR (Moisture Vapour Transfer Rate) of 15,000 g per square metre over a period of 24hrs. So if your jacket is made from 1.3 square metres of material, it will transfer 19.5 litres of perspiration every 24 hrs.
The fabric used, has a hard wearing plain weave nylon face with an inner waterproof layer, which is protected on the inside by a polyester mesh lining for enhanced breathability with a tough taffeta nylon lining where necessary.
The outer surface of the material is treated with a Durable Water Repellent (DWR) surface treatment. This prevents the surface of the material from wetting out when it rains and therefore enables perspiration vapour to escape from the inside even when its raining. The DWR will wear off in time and is best replenished every six months or so when the garment is washed. This can be done using the reproofing products supplied by Nikwax and Grangers.