Not all single weight papers are the same thickness, but I do not know if
there is enough variation between them to really see the difference. For
what is is worth, the thinnest paper I have ever used is Ilford's Ilfobrom,
a graded, single weight fibre based paper. Almost impossible to dry flat
too. :) I do not know if it is still available anymore. FB papers are
harder and ahrder to find in stock anymore at most camera shops, and graded
FB papers especially so.
joe
http://www.multiboard.com/~joneil
B&W, Large Format Images From Southern Ontario