Your answer seems clear and I think the only part of my post you deleted was what I had quoted from your initial posting. Ya gotta watch yourself carefully when you're wielding those "moderator superpowers", kinda like the Charlie Chaplin carrying a ladder. I was just curious because everything I have read suggests that toning first is optimum.
I think the reason you are getting excessive bleach-back is simply the KRST is quite bit more concentrated that necessary. As an example, 1+200 works well on Vandyke (toning times in the 10 minute range and a measureable increase in dmax vs untoned). I know that albumen and VDB sensitizer are not the same but the starting point of the image (silver nitrate) and the root problem (bleach back due to thiosulfite/thiocyante in the toner) are similar. I have used KRST on both Abumen works POP and old studio proof and the problem is similar. I had to give a presentation/demonstration recently, part of which was a toning sequence for VDB. I sifted through my small collection of ancient photgraphic how-to books on the premise that research was the better part of valor when faced with public speaking. What I gleaned from my survey of available literature was: toning first was traditionally done to avoid or mitigate bleach back, and VDB prints do not seem to traditonally have been toned. Anyway, toning first seemed the logical nod to received wisdom and it seems to work well if you get the dilution right. As to economy vs gold toning 5ml/litre really milks a long life out of a bottle of KRST.
Originally Posted by David A. Goldfarb