One thing that's always confused me with my Pt/Pd prints is the way the negative seems to change the print tone. I find the area outside the negative consistantly turns a rich middle brown, but the darkest area of the negative (i.e. clearest bits of film) have a much blacker tone with a visibly greater dmax. My pet theory is that the film base (HP5+) filters out part of the UV spectrum that Pt/Pd is sensitive to. But has anyone else experienced this? And if so, do you have any better ideas as to why it happens?