Lo and behold guys!
WATER! lots and for long time.
Rule is, most paper snipes/paper tape use water. Very rarely do you need to add chemicals.
CAUTION: You need to soak well and for long time. So the paper is very fragile to handle. You could very easy tear or mush the paper. Naturally you don't have to soak more than just the part were the snipe is attached.
Chemicals are for all types of plastic tape or Filmoplast that appears to be paper but have a gummy archival membrane.
All the best,
dario.