I've been using some of my inherited stash of Ilfobrom paper this evening, (it's the original Ilfobrom not the modern galerie stuff).
Previously I'd had no reason to use other then the grade 3, but tonight I wanted to lower the contrast so used grade 1 instead (dont have any grade2). This paper actually increased the contrast, so I tried the grade 5 and found it to be very low contrast. It wouldn't be the first time I've looked stupid in public, but I thought as the grade number increased so did the contrast ?
To get a reference I ended up making exactly the same exposure on each of the 4 grades I have (1,3,4 and 5). These appear to decrease in contrast going from 1 up to 5 (grade 1 has white highlights and black shadows, as the box number increases the highlights darken and the shadows lighten).
Of note is the grade 5 is noticeably lighter than the others (which are all reasonably uniform exposure wise) and a search on the 'net and here on APUG shows that the grade 5 was (is) a stop slower than the other grades, which tends to discount my first theory that the papers had all been put back in the wrong boxes. The search also suggested that age tends to lower the actual grade of the paper, but I would have thought this would have resulted in the paper going from grade 5 now = grade 1 or 2 down to grade 1 now = totally fogged, rather than an apparent inversion of contrast grades ?
Ultimately I'm not going to be using this particular type of paper again once these boxes have been used, and I now know how they compare in contrast, but I'm curious as to why the numbers on the box seem to be the inverse of the widely recognised contrast progression.
Any thoughts ?
Crispin