What do yo mean by color wash?

I only use the term to mean the whole technique I mentioned above of desaturating, through to adding a colour layer on top and then blending that so the lower layer shows through. Probably not the proper term!!

Now my question!! What's press overlay??

I have a link to vered Brush (I think it's one I've been working my way through), but I've not heard of touchstone art. Of course, if I get more brushes, I'll need to improve my use of brushes - it's something I need to practice. I'll be glad of the links - thanks. :-)