Question How can you tell soft porous paper without gum
Answer Hi Terry,
First, take a stamp that MUST be on hard paper (I suggest the common 3c 1861 stamp (Scott #65) or the common 3c 1869 stamp (Scott #114) but ANY early stamp that must be hard paper will do. Then take a stamp that MUST be on soft paper (any stamp issued after 1879, but before 1903, will do. I suggest Scott #210). Then hold them side by side up to light. You should notice by trying to look THROUGH the stamps at the light that the soft paper stamp has a lot more porosity (a weave that is obvious, whereas the had paper appears more "solid"). Once you clearly can see the difference, you should be able to always identify soft paper, whether it has gum or not.