Since this was posted in the color category, I assume that Dmin was actually meant. Dmin variances of color paper could be determined with a B/W densitometer whereas any density of color paper should be determined with a color densitometer. A B/W densitometer might be fooled, depending on its spectral sensitivity (same problem occures with pyro stain).
Originally Posted by ann
Although Dmin is usually defined as the paper base, you may also zero your densitometer on the brightest paper you have and measure relative differences to other papers. However, I do not expect that they lie beyond the second decimal and thus not within the significant measurement range of usual photographic densitometers.
More interestingly is usually the difference between Dmin before and after development (resp. in comparison with an unexposed and fixed sheet). While the paper ages and the developer wears or the temperature gets higher, Dmin increases and this can vary between different makes. I found that Fuji Crystal Archive is usually more invariant to these parameters than other papers. And to me, all modern papers have the same white base, obviously including some kind of "brighteners".