Ultrasonic Misting- Part One

I’ve been busy the past several months in the Paper Lab getting together the parts, purchase requests and wherewithal to construct an ultrasonic mister in order to care for a group of paintings needing some attention.

Last year, Lilly Library received a generous gift of over 450 paintings by the playwright, screenwriter and producer Clifford Odets http://www.indiana.edu/~liblilly/blog/new-donation-the-artwork-of-clifford-odets/

Soon after the library received this gift, the Paper Lab hinged and matted nearly all of the paintings for storage and safer handling and access. During this process we noticed that a number of the artworks were suffering from condition issues related to the paint media that Odets chose. Much of the work relies on a layering method of drawing and painting over wax crayon. Odets would scratch through the pastel and gouache paints he favored to reveal the crayon beneath (a.k.a. sgraffito).

Here is a photograph of one such painting- on the back of a postcard- in raking light.

You can see how the teal blue paint has been scratched away to reveal orange, pink and purple wax crayon beneath. However, though the technique allowed Odets to create some wonderful images, it also created what we conservators refer to as inherent vice. There is little adhesion between the media layers and as the upper water-based paint layers dried, they began to shrink in place causing minute cracks and more seriously, flaking and loss. This close-up shows what I mean (poor little flaky fish!)

 

In these circumstances, conservators perform a process called consolidationTypically, the consolidant is a type of adhesive carefully chosen for a number of factors including, but not limited to, compatibility with the object physically, visually and chemically, ease of preparation, ease of application, quality of bond strength and ageing characteristics. Normally, the process would be carried out under a low-power microscope using a small brush and delicately applying the consolidant to the cracks and underneath the lifting paint, fastening it back down. With these paintings the scale of damage prohibits such an approach- the fish above is 2cm long, which makes each of the tiny flakes far smaller than a millimeter in dimension. My fine motor skills are excellent, but not that excellent!

Another method is called for: that of Ultrasonic Misting. Developed by the Canadian Conservation Institute in 1990, the ultrasonic mister allows greater control of the whole process of consolidation of powdery paint and pigments. Unfortunately one can’t readily buy such systems- at least not at affordable rates for an aerosol generator- so I set out to construct one myself. There are a number of published articles explaining how to make one as well as a number of institutions who have blogged about it in the past, such as this account from the UCLA/Getty Conservation Program. Within a month or so I had purchased and cannibalized the necessary parts and had it up and running:

What the device consists of is a domestic ultrasonic humidifier, with the upper water reservoir removed. We use this very humidifier routinely in the lab for the relaxation of library materials, so it was good to have on hand! Resting in about one inch of water over the oscillator within the humidifier is a LDPE plastic bottle containing the consolidant adhesive. Ultrasonic frequencies generated in the base of the humidifier travel through the bottle and cause cavitation to occur, generating a fine mist of adhesive to rise from the liquid. A pump (the large white cube in the background to the left) was borrowed from our vacuum suction table to drive air into the bottle (through the clear tube entering the back of the bottle), and then the adhesive-laden water vapor finds its way out the top, through another length of tube to be emitted through a small applicator nozzle. Also sitting in front of the device is the consolidant of choice. Can you guess what it is? There is a clue in the painting I chose to include earlier…

Next week, I’ll cover the pros and cons of the design and talk about the success of the treatments.

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

 

Hornak Drawings Conservation Treatment

This month we worked on three drawings by Ian Hornak, an American artist who worked in the late 20th century. His early work consisted of erotic pen and ink drawings and later consisted of photorealistic landscapes and portraits in acrylic on canvas.

One drawing had masking tape around the edges, another was spot-adhered to matboard, and the third was fully-adhered to matboard. All three had surface dirt and minor tears.

Ian_Hornak05_before

Our treatment plan was to remove the matboard, surface clean the drawings, spot-test and wash the items, and lastly, mend any tears with paste and Japanese paper.

Ian_Hornak01

If you look closely, you may be able to see the graphite under-drawing. A real treat was seeing an initial sketch on the back of that same drawing.

Ian_Hornak04

These pieces will be included in an exhibition at The Kinsey Institute, opening next month. The opening reception will be on January 24th from 5-7pm with an introductory talk at 4pm by Eric Ian Hornak Spoutz, the artist’s nephew and Executive Director of the Ian Hornak Foundation. Hope to see you there!

Ian_Hornak02 Ian_Hornak03

For more information on the exhibit please visit:
http://kinseyinstitute.org/services/gallery.html

And for more info on the artist:
http://ianhornak.com/
http://en.wikipedia.org/wiki/Ian_Hornak

-Arini Esarey