The idea of trying to gauge from a wet print whether the "first
perceptible tone appears to be fading" is awesome. Especially since VDB
has the most extreme dry-down known to the history of photography.
> Chrome is an effetive intensifier but there are risks of staining the negs. It
> is far safer and more effective to contact the neg to make an inter-positive and
> make an inter-negative from the inter-positive increasing the contrast at each
> stage.
But, if you're working large, quite a bit more expensive -- not to mention
the time, trouble, &, no doubt, degradation of the image.
Judy