The only link I have is this:
http://www.armorama.com/modules.php?op= ... 221&page=3I usually use the first ..."thing" I found at the reach of my hands; for instance:
* Tamiya putty with or without fine sand, then painted with acrilic (mixed with Tamiya Flat Base for dry mud)
* Fine sand and pigments, glued with acrilic medium (matt or not, depends if I want dry or fresh mud) Maybe mixed with pigments or just painted with acrilic.
Hope this helps
DarĂo