Amalgam
Journeyman
probably not even water, just make kindling from the carpentry? menu then use that for blank scrolls.
Can logs/boards be converted to kindling? This should be added to the menu, if not. Kindling could also be the failed result of converting logs into boards! (I believe there should be a carpentry skill-check when performing this action). Perhaps kindling could also be obtained by using a bladed weapon on a log...
I suppose, for sake of simplicity, you could do without water... but if we're talking about making blank scrolls it really should be a two-part process including the addition (or proximity) of water.
Also, what about hides or pieces of leather converted to parchment? This might also be viable.