David,
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.
Celac.


Quote Originally Posted by David A. Goldfarb
I'm not really sure. I did take a couple of slips of exposed albumen paper and tried one one way and one the other, and the one that I did selenium first then fixer lost more density in the toner than the one that I did fixer first, so I suspect that's the reason.

Generally, one exposes albumen paper so that the untoned print is about 1.5 to 2 stops "too dark," because it lightens up in the toner, then lightens more in the fixer, though it then has some dry down, so it gets a little of the density back.

I suppose another issue might be that gold-alkali toners are alkaline, and fixing first might more quickly exhaust or contaminate the gold toner, where that wouldn't necessarily be a problem with selenium (since we do it all the time with regular silver gelatin papers).