true... I agree that the method of testing here doesn't exactly simulate what happenes in our case... all it does is show the amazing impact resistance this material has. Nevertheless, I do think that you were taking about a complete split insdead of a large enough crack to allow water to penetrate the top.
Also, I NEVER claimed that this is proof. It is merely a piece of information to take into consideration when postualting a theory regarding the problem we are trying to solve. Lousy choice of words here, BillA.
Anyhow... where are the leaks? I have never talked to anyone who experienced one!
http://www.material.freeserve.co.uk/mats.htm#plas1
http://www.material.freeserve.co.uk/mats.htm#plas2
Ok. Here are finally some numbers, and BillA, I may just be getting closer to some of the proof you said I already stated