This should really be accompanied with images of your example, and some notes with your experiences of the process.
Without a final image, Im a bit reluctant to attack my next model with water and a tooth brush. Will this work on etch as well, or will the abuse knock off most of it? What about decals? Will one-colour weathering be a bit boring?
Not meaning to be harsh or discredit your method, but I´m not really sold on it!