I've used Ilford's method in the past with good results, with the slower films. Not sure about the developing times for HP5+, but I would have thought that a similar time to Pan F would be a good starting point.
Originally Posted by NDP_2010
As Ilford say, 2-4 times the basic second exposure should not cause problems (better more than too little time), but excessive exposure or sunlight can cause problems.
I recall once that the bleach stripped the emulsion completely!
(Sulphuric acid and permanganate is quite strong stuff) I can't recall the type of film, might have been an older film with a softer emulsion, but IIRC I think that I might have given the film too long in the bleach (just to be on the safe side? ). Best to stick to the recommended times.
Not sure about keeping times of the solutions..with all processing I tend to discard the working solutions after the session, even if it means storing up sufficient films to use up the chemicals economically.
Hope you sort out any problems...projected B & W slides look amazing if well done.