I was surfing Darkroom printing on youtube. I saw interesting vid of a Japanese fellow , a young guy.. doing darkroom printing. Everything made sence, however there was one part that caught my curiuosity.. While print was still wet, hey put it in a open face cabinet and treated a couple area with some sort of chemical treatment with a brush.. it wasn't spot toning it was something else. Can anyone here tell maybe from was discribe what he might be doing.