what is _minimum_ humidity for PVA?

[lukejaeger 0]

We started using a PolyBox and vacuum containers to keep our PVA from absorbing too much moisture during the extremely rainy summer & fall.
Now it's winter and we have the opposite problem. PVA gets so dry and brittle that it snaps like raw spaghetti when you try to load it.

 

We converted our PolyBox into a humidor by putting a damp sponge inside it instead of desiccant, plus a little muffin fan to circulate the air in there. At this moment, the PolyBox sensor says the humidity is 85% in the box (while general humidity readings in the rest of the room have been between 25% and 35%).

What is the _minimum_ humidity level we should be aiming for in our makerspace? 

[UlrichC-DE 114]

I would have sponaneously claimed that PVA feels most comfortable between 20% and 30%.

At 85% it no longer breaks, but it does stick together. So it's more likely to be between 30 and 40%.

 

For a makerspace, I would lean towards between 40 and 50%.