NOS No.5 Buttpad Grunge (not cosmo)

[IanD]

Just to bump this a bit - I got a "NOS" pad from Liberty Tree, it was covered in the same white residue, which cleaned off quite easily with a toothbrush and dish washing liquid (Dawn). I compared it to the pad on my unissued/unfired No5 and it was an exact match, except that it was actually soft and pliable. I'm thinking that oil and/or cosmoline might speed up the hardening of the rubber pad, and using talc stops it from absorbing oil.