question at the end, but here's the back story.... after promising to teach a friend cyanotype, and then having a problem with my chemicals, we decided to give vandyke a try instead. i, being the one with alt-proc experience (kallitype, cyano), was charged with figuring it out. my friend had some year-and-a-half old vandyke sensitizer solution, which was possibly still viable. so i gave it a go. i first attempted to establish my exposure time and curves. however even at the smallest time interval on my test strip, the highlights were not white. very yellow. i did some reading (apparently wynn white is the only one ever to discuss vandyke on the internet!) and apparently print dark and then reduce/bleach was the preferred method. so ok, i tried that and it worked. my curves were a bit whack however, because i had based it on what had turned out to be too much exposure time. so tonight i thought i'd give it another go. at roughly 1 stop less exposure...but wait. the highlights are paper-white! whereas before, 2 stops less exposure and they were still very beige. it's the same sensitizer, although i did filter the lumps out. it's the same paper, two coats of sensitizer, same UV source, same procedure. the only difference that comes to mind is that this time, i printed when the paper was barely dry (maybe two hours after second coat, and paper felt cool but not actually damp). previously, the paper had about eight hours to dry, and was bone dry. an alternat explanation, and it's a stretch, but perhaps the sensitizer fogged from some extremely minor exposure during the longer drying time? the question: anyone heard of highlight differences based on how long vandyke sensitizer has been drying for?