Thin rag photobase = 100% cotton fiber, 60 gram/meter2, manufactured to be
compatible with photographic emulsions and processing chemistry.
This weight was a very close approximation to the "BFK Rive #72" commonly
coated in the 1870's for albumen printing. (I have seen that watermark most
often on mammoth plate Muybridge prints from the 1872 Yosemite series.)
As to the correlation between surface and paper thickness, what others have
already said is consistent with our expeience: thicker papers yield flatter
and more matte prints.
Keep in mind that vintage albumen prints were almost always wet mounted.
They consequently stretched taught on the surface of the mounting board
when they dried. That stretch, along with using a thin paper with little
surface texture to begin with, is a major factor in producing an albumen
print's characteristic surface quality.
Doug Munson
Chicago Albumen Works
Front Street
Housatonic, MA 01236
413.274.6901 tel
413.274.6934 fax
albuwrks@bcn.net