Quote Originally Posted by holmburgers View Post
I guess Epsom salt (magnesium sulfate) is a good choice, if dehydrated sufficiently in an oven beforehand. I'll probably give this a go.

That omega link is a bit heady...
Well...I don't see MgSO4 on the list, so it's tough to assess how effective it would be. Keep in mind that those salts listed will maintain a given RH in a closed environment when the salt is in a "slush" with water (i.e. far less water than required to dissolve all the salt).

I'm not sure they're the right choice for desiccating a tissue. Silica gel is far superior for that purpose, and it can be "recharged" in an oven, as well.

Quote Originally Posted by holmburgers View Post
That omega link is a bit heady...
Just ignore the text on how they collected the data. The tables are pretty straightforward...the RH the salts maintain varies with temperature, some are more stable with temperature, and some less. Since most people work in a relatively narrow range of about 15C to maybe 30C, the temperature variation is less critical.

Also, keep in mind that completely dry un-sensitized tissues improves their keeping qualities. But sensitized tissues need a little moisture in them to improve their printing speed. I don't know if anyone has ever collected any data to see if there is a "sweet spot" for moisture content of a sensitized tissue.

--Greg