In Tim Rudman's Book he states 3 minutes at 1:9 dilution a minimum for archival benefits. On both MGIV and MGWT this will produce a color change, though not unpleasant. And with MGIV I usually tone twice this amount of time anyway. MGWT will do amazing splits with selenium at the 1:9 dilution after about 6-8 minutes the shadows are plummy brown and the highlights a coolish silver. There is a moment in time depending on the photograph where the shadow tones begin to creep into the midtones. Pulled at this point it is just beautiful!!.. for the right image of course.
Originally Posted by Mahler_one