Thanks guys. Well, this is all hit and miss stuff at first. Then I keep pushing and tweaking until I reach the limit, meaning, no matter what I do I'm never going to get what I want. Some I like and some are trashed.
It's a combination of models and materials, both I make (mostly). The nodes lately have become a good source for experiment. The nodes being partly alpha knock out parts of the models. So basically I never really know what is going to happen.
Cheers
Terry