Two interns from University of Southern Maine and Montserrat College of Art working at the Maine Historical Society Research Library in Portland, Maine, demonstrate how to safely humidify and flatten rolled Coombs Brothers architectural drawings.
Comment from a paper conservator via Archives List:
The dusting off was a bit harsh for public viewing, though actually those starch cloth things are pretty tough. But still, it’s best to put your BEST and gentlest foot forward for the public. The dust was just going on the table; that’s ok. (We usually surface clean things on a “tray” made of craft paper folded up on three sides, and then we can throw it away or empty it out without having dust and crumbs going all over the table. We often surface clean with grated eraser crumbs rubbed across the paper, and they tend to get everywhere.) A bit more worrying was all the rust and crumbly green verdigris powder on the fasteners, and then on her hands, and the same surface cleaning brush, and all the pages as she was taking them apart. Abrasive!
So here are the bullet points of the main things I don’t like in the theory, setting aside the rough practice demonstrated there:
* Humidifying things while rolled up and vertical is dangerous because
o it can dent the “bottom” edge of the roll that’s in contact with the trash can
o any condensation buildup will form drops that will run down the surface of the paper – especially if hot water is used, as suggested
o the object might stick to itself while rolled
* Its very slow, which makes it impractical for a big collection
However, to be fair, the slowness of that method can be a good thing that prevents condensation. And those starch cloth things they were working with can be tricky, so whoever came up with that scheme may have had starch cloth’s characteristics particularly in mind. I think the interns were just doing and filming what they were taught to do without necessarily knowing the reasons for all of the steps. (Such as saying at the beginning, “Only drawings on linen should be humidified.”) Now back to the bullets.
* Humidifying by spraying with a standard plastic spray bottle is dangerous because:
o The water droplets are large, which can cause tide-lines, bleeding and uneven humidification
o It’s always best to humidify front and back evenly, but spraying only on the back doesn’t do that, and spraying on the front with such large water droplets defeats the purpose of using spray as a safer method
* Items shouldn’t be sprayed while lying on the blotters, because it dampens the blotters that need to be dry
* Items put between blotters should be weighted down by heavy boards or put in a press to avoid uneven expansion and contraction when drying, and to ensure that they dry flat (which the ones in the video were not)
* It’s preferable to have three layers of blotter between each layer of objects being flattened, to better absorb the moisture and prevent mold growth
* It’s also preferable to put the object between layers of nonwoven polyester (eg Hollytex, Reemay, or Bondina) to prevent the object from sticking to the blotter or the media from transferring to the blotter
* The objects should be left flattening for much more than 8 hours that they recommend, ideally 2-3 days or more to make sure they’re completely dry – otherwise they might get moldy in storage or they might revert to their previous wrinkles.