On May 6, 2011 I hydrostatic head tested the May 4, 2011 introduced Thru-Hiker Shield ™ silnylon per the ISO 811 standard. Three random spots averaged 3,398 mm H2O which is dramatically better than any other light silnylon tested to date. By contrast, the Thru-Hiker's previously marketed 1.1 oz Sil averaged 1,200 mm H2O.
The only other similar-weight-non-CTF3 material that tested in this range was a sil/PU sample not part of the BPL Submissions. Unfortunately its PU coating has a polyester backbone (economical and flexible in cold weather) which is very susceptible to hydrolysis. In laymen terms this means that the PU starts to break apart if it is wet for prolonged periods and, in contrast, silnylons will not degrade this way.
Although I haven’t tested this new material after aging, comparing virgin HH reading, this Shield (TM) silnylon has the best combination of light weight and high hydrostatic head that I have tested to date (3,398 mm H2O HH, 1.4 oz/yd2, and $11.95 per linear yd - 60” width).