8/1/11 Edit between asteriks
1. Subsequent testing of CTF3 and other light weight shelter samples, from a broad range of sources, can be found at http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=45026
The above indicates that CTF3 (Cuben), using .08 Mylar thickness, is frequently less than the ISO 811 minimum threshold for being rainproof at 1,500 mm H20. This occurs in some samples before use and most samples after one or more aging cycles; each of which is designed to simulate a week of field use in the rain. THIS WAS NOT A MLD UNIQUE PROBLEM; IT APPEARED TO BE A COMMON .08 MYLAR CTF3 (CUBEN) PROBLEM DURING THE TESTING PERIOD.
THE SECRET WAS THE PERFORMANCE OF CTF3 .08 MYLAR SIX YEARS AFTER FIRST BEING USED TO PRODUCE LIGHT WEIGHT SHELTERS. I AM NOT AWARE OF MLD ATTEMTPTING TO MISLEAD ME.
One Protocol B submission of .08 Mylar CTF3 exceeded the threshold for being rainproof both initially and after aging. In addition, I have read numerous 2nd hand reports on BPL where field testers state they have not experienced any leakage in field use. Possibly the problem no longer exists but, I have not been involved in any subsequent testing after the Protocol B thread.
2. MLD PROMPTLY REFUNDED MY MONEY AFTER I REPORTED THAT I WAS NOT SATIFIED WITH THE QUALITY OF THEIR PRODUCT USING CTF3 (CUBEN) WITH .08 MYLAR. THE PRODUCT WAS ONLY TESTED BY BEING SET UP IN MY YARD FOR THREE DAYS DURING A SERIES OF SF BAY AREA WINTER RAIN STORMS. AFTER NOTICING WATER DROPLETS NEAR THE APEX OF THE WIDEST END, I TESTED THE HYDROSTATIC HEAD USING THE ISO 811 PROCEDURE.
3. I HAVE READ 3ND PARTY FIELD REPORTS WHERE OTHERS HAVE NOT EXPERIENCED LEAKAGE IN CTF3 (CUBEN) USING .08 MYLAR. SINCE ONE PROTOCOL B SUBMISSION, USING .08 MYLAR, TESTED RAINPROOF BOTH IN ITS VIRGIN STATE AND AFTER FOUR CYCLES OF SIMULATED AGING, THE PROBLEM THAT I EXPERIENCED DOES NOT APPEAR TO BE UNIVERSAL.)
I hydrostatic head tested a new MLD Grace Duo tarp today. It was previously set up in my yard during moderate winds and rains for only 3 days total use. Afterwards the hydrostatic head tested worse than most silnylons at 422 mm H2O. I tested 3 random areas and got the same results in each spot.
I AM SHOCKED! I also measured the air porosity and it is 0. This means it would serve well as a sail but it is a poor solution for heavy rain protection. Has anyone else ever tested the hydrostatic head of Cuben?
This thread is NOT to rehash the physics of dynamic versus static pressures; it is to discuss the hydrostatic head of Cuben measurement that I made or you made. For a rehash of how static hydrostatic head testing relates to dynamic hydrostatic pressure you can read and add comments to this old thread: http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=43902&disable_pagination=1