Absorption of water vapor in paper

[carlosgw]

Anyone have a reference for paper moisture absorption.
Extrapolating from the ASHRAE Fundamentals chapter on Sorbents – Absorption of water is driven by vapor pressure/moisture content of air as opposed to relative humidity. Also the cooler the paper, the higher the absorption. I want to verify this.

 

[Shophound]

This organization has very good information regarding storage of materials under various environmental conditions:

https://www.imagepermanenceinstitute.org/

 

[KiwiMace]

The content of the ASHRAE fundamentals section on sorption (2009 chap 32) is biased towards aBsorption and applications in dehumidification, rather than the condition of the sorption material itself.

The repeated descriptions of vapour pressure refer to the conditions at the surface of the material rather than the driving force for getting to that condition. Paper and moist air find equilibrium through aDsorption rather than aBsorption, which is driven by RH.

Adsorption is water molecules finding a home in the porous surface of the material. Absorption is like table salt going clumpy in humid air, forming a compound like NaCl.xH2O.

Paper and wood find an equilibrium moisture content up to saturation at about 25-30% of the dry mass. This varies for type of wood/fiber, paper manufacturing method and only a little for temperature.

Google "sorption isotherm paper" and you'll find lots of info like this:

http://www.tappi.org/Downloads/unsorted/UNTITLED---94jul075pdf.aspx

 

[carlosgw]

Thanks.
Looking at that particular article the %-RH curve suggests a linear relationship with humidity ration. However it looks much more dependent on temperature which makes sense for a surface situation. (I have not googled other info)
My application is a manufacturing process involving thin paper which needs to have a certain water content so the manufacturer is trying to raise the RH in the space to reach this water content (the paper as received from the supplier is too dry). (it is not doing the cardboard boxes sitting off to the side used to packeage the product any good)
They are humidifying in the summer and having issues. If they are having a hard time in the summer, the winter will be much worse.