...Good Lord, that's not a toner, it's a bleach!
I've just spent an enjoyable hour playing with some of the Fotospeed toners I've had lying around for ages and not done anything with, using a selection of identical 'normally exposed' prints on Kentmere Bromide paper.
The Vanadium Yellow is more like a bleach than a toner - should I heavily overexpose prints to use this toner? I managed to create some very cool psychedelic solarisation effects split toning with the 'yellow' followed by blue, but not a lot of cop actually getting a decent yellow tone. (I haven't tried the Titanium Yellow yet, which I suspect behaves better.)
(Anyone got experience of Bromide paper & these toners generally?)