I found this on the web, it's maby intersting because we use a lot of these substrates in our hobby. It is an article about physico-chemical an physical properties of some substrates used in horticulture
http://www.ulmer.de/Artikel.dll/gawi_2_MTg3MA.PDF?UID=E5F6E0B9FA0F31A5F556544E58A0D6EFEA779D330B64E674
_________________
Chris admin