Why did your hydrostatic head figures change so much in 2017?
In 2017, we changed how we report our hydrostatic head figures so that they are more in line with common practice in the industry. Prior to that, we had used a much more conservative testing protocol. The new figures will make it easier for customers to compare different manufacturer’s materials throughout the industry.
In the 1980s, the ripstop construction in nylon fabrics was the limiting factor for hydrostatic head measurements: water could more easily pass through the ripstop cross thread area than it could in the rest of the fabric, and it was difficult to get fabrics to have a very high hydrostatic head number even if the waterproofness was much higher between the ripstop threads. We specified to our fabric supplier that our fabrics have a minimum 3000 mm hydrostatic head value, measured with the industry standard ISO 811 test. This provided fully dependable waterproofness, and was achievable with fabrics of the time. Concurrently, we also had (and still have) testing protocols for durability, where the fabric is mechanically rubbed for a set time. This helps us see how the fabric’s coating performs.
Because we are innately conservative and quality-focused, we combined the two protocols – the rubbing procedure and the ISO 811 hydrostatic head test – and specified that our fabric supplier deliver fabrics with a a minimum of 3000 mm after the rubbing procedure.
Over time, as weaving and coating technology improved, the “as received” hydrostatic head numbers became much higher, so today (2017) it makes more sense to report the “as received” numbers. This is also how the majority of manufacturers in the outdoor industry report their figures, so now customers can better compare fabrics from various manufacturers.