I have used the laurel Mountain brown for browning and it's wonderful stuff. But I try to do the superclean drill and consider the capability of the solution as insurance and I've never been disappointed. Now I have gotten overly aggressive with the damp box and got a coarser brown, not the fine rust you're looking for - start all over.

The key elements in human thinking are not numbers but labels of fuzzy sets. -- L. Zadeh

Which explains a lot.