I've used it for bolsters and it was OK. I tried it on a blade the results i got looked blotchy to me. It doesn't replace a salt tank but for small parts it works OK
I buy a charcoal sketching stick, finely scrape it into a container, mix in a bit of oil to thin it out (not WD 40) and there you go, a non staining transfer paste. Well you do need a small brush and you do want a covering but thin, not like icing on a cake. Frank