By the way the same technique works for colored pencil but you have to go lighter with the sand paper to get the proper particles.
experiment is the trick. this makes good dirt for 1/72 trucks and tanks.
Instructions have you remove the struts at the beginning (they are inverted inwards) and are replaced with new ones later on.
Thanks guys. Will post some progrtess shots over the weekend. Unlike my armour builds, am having to paint parts first before I can start assembly and as I am using oils for wood grain it's slow progress waiting for them to dry.... All good fun though