Black wash can be a little tricky sometimes, and there are a few different methods for applying it. One is to mix your paint with a fast drying liquid ( such as window cleaner )
put it in a spray bottle and apply.Because of its thinned down form the paint should pool in the lower part off subject ( gauntlets, jet pack or other prop ). This method can be great to weather all the nooks and crannies, as well as giving a light coating on the raised parts. You shouldn't need to wipe, in fact I myself wouldn't. Its best to blot at the area with a scrunched piece of tissue or paper. As you blot the paper will lift the paint and break up the newly applied paint. ( Don't wait to long to blot. Once the paint is dry it wont come off ) Remember it is always best to apply weathering in stages. A few light coats is easier to control than one thick coat.
Good luck on your weather, Hope this helped. There are some great tutorials on TDH, do a search and you should find heaps more.