Great Rec thanks for the tip.Native, welcome to the forum! Let me suggest a site for you to explore---it's not a tutorial, but I think you'll find what you need if you follow the threads. It's a forum that specializes in scratch modelling. Look at the tabs at the top and click "Search" and type in "weathering". I think you'll find a wealth of info there on it and other topics:
Good luck and best wishes on it!