Joe, AK interactive washes are thin enamels, pastel powders are just artist chalk pastels ground up in a jar. Enamels, oils, pastel sticks and chalk make fine weathering supplies. I will be using good old desert dirt from my backyard when it is time to dust up my truck. I'll sift it into an old butter container and brush it on.
I have a couple of small dollar store ladies eye make up compacts. These have a nice waxy eye liner in various rust or brown shades. They are the bomb for rusty exhaust pipes. They even have an applicator but I use a flat brush mostly.
Seriously, look outside the hobby shop, and treat yourself to the make up isle.
G