Mass Humidification

We mentioned a month or two ago a long-term project we have going with the Wylie House on campus. Roughly 5000 letters of correspondence are being cleaned, repaired and rehoused for eventual storage at ALF– the compact off-site storage facility our library system has on campus. Surface cleaning and mending the letters has been relatively trouble free, but early on we realized that the stage of humidification (prior to pressing) was causing a workflow log jam. The first efforts involved utilizing the dome on our cold suction table. An ultrasonic humidifier feeds humidified air into the chamber and after a couple of hours, the letters are damp and ready for pressing.

We could only humidify about twelve to fifteen leaves at a go with this method, so we added on another humidification technique by turning our large sink into a chamber, supplied with wet blotters beneath a layer of Gore-Tex. Another dozen or so letters could be prepped this way each day.

sink humidification

Even with these two options, pressing efforts were being stalled, causing us to go back to our client library with a much longer than originally projected completion date. Thankfully, inspiration struck and it occurred to us that it may be possible to convert our print drying rack into a Mass Humidification Device.

drying rackWe constructed a slip cover of sorts out of plastic sheeting and Velcro tape that fully encloses the rack, except for the bottom. With a generous ‘dust ruffle’ of sheeting at the base, not much water vapor seems to leak out. The cover is constructed of two parts: the larger is a single sheet, with stapled ‘seams’ giving some rigidity to five ‘panels’ to wrap around the rack, with closure in the front; the second piece is a top that Velcro bonds to this upright portion.mass humid test1

The above photo shows initial tests introducing humidity into the chamber by way of the ultrasonic option. After several hours, the %RH was only up to ~70%. Opening up the cover revealed that the humid air wasn’t dissipating into the overall volume fast enough, before condensation occurred at the point of introduction. In other words, we had liquid water and dripping where the hose made contact with one of the shelves, but dryness elsewhere. A second set of tests with wet blotters proved much more effective with speed of humidification and distribution of water vapor.

We are now able to fill 20-25 shelves with correspondence per day. A wet blotter is placed between every 4-5 shelves of letters. Humidification takes place over about six hours. We empty the rack of its contents at the end of the day, and create a press stack for overnight drying and flattening.  The process is repeated the next day, ensuring that items are pressed for 24 hours, which is effective enough for single-leaved, stationery-weight paper.  Foldering and boxing then occurs.

papers on rackpressing stack

-submitted by Doug Sanders

 

We’re back!

It’s been nearly a year since the last blog post. Within the Preservation Department we’ve had some personnel changes, a sabbatical, and day-to-day busy-ness which have all conspired to the neglect of this blog. However, more recently we’ve become inspired and determined to share the interesting, satisfying and productive work we do with the greater public. To us, the public can mean fellow staff within Indiana University Bloomington Libraries, the IUB campus community as a whole, and of course the wider audience of like-minded individuals in preservation and conservation labs across the country.

We hope that you’ll see more posts from all of us who work within the department; even some guest entries by student employees (those who can be cajoled!) and perhaps some staff within the Library who ally themselves with or benefit from our operations.

To start things off I’d like to highlight a project we’ve been working on in the Paper Lab for the past month. The Wylie House is an historic house museum here on the IU Bloomington campus, originally built by the first President of Indiana University, Andrew Wylie. Within the museum’s collections are over 5000 letters of correspondence involving several generations of family members, many of which have been transcribed. Even though Carey Beam, Interim Director and Graduate Assistant Abi Parker, as well as previous Director Jo Burgess and many other interns have done a great job storing and transcribing these letters, they’ve now come to the Paper Lab for surface cleaning, mending, pressing and migration to a new storage format of archival document folders and cubic foot storage boxes. It’s a big project with an estimated completion date of May 2014. We’re finding out all sorts of interesting things while working on it, which will be the subject of several posts in the coming months. For now, here are some pictures of the ongoing work.

posted by Doug Sanders, Paper Conservator

mending1

surface cleaning1pressing stack