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.

Writings of Brilliance

We recently had two documents in the lab exhibiting a noteworthy effect. They were contracts for a violinist’s performance in Lyon dating from the time of the French Revolution, from a Lilly Library collection. Interesting enough, but what really caught my eye was how the ink in selected areas sparkled when turned in the light. Low-power microscopy suggests some type of micaceous material. For me, the question is, was this used as a drying pounce with the bonus of adding some ‘bling’ to one’s signature? Or was the effect alone the chief reason for use? In working with manuscripts for many years, the two other times I’ve seen this were also in French Revolution-era documents. Incidentally, this effect should not be confused with the well-documented and studied crystalline growth one can sometimes see on iron gall ink (whitish or yellowish crystals).

I tried to capture the effect as best as I could by taking multiple exposures with the angle of incident light varying, and then stitching them all together in Photoshop for a rough .gif animation. The effect is restricted to the area associated with the word ‘Bowes’ and the passage of text at the bottom of the view ending with the name “Carpentier”.

gif animation of sparkling ink

There’s a date visible too- 14th of Fructidor, year 13. This references the French Republican Calendar which is itself a fascinating topic. I found a calendar converter online and it looks like this is August 31, 1806, for us Gregorian-minded folks.

p.s. if you want to see a higher resolution animation leave a comment with your email and I’ll send you a file.

Conservation insights from the 1870s

In the Paper Lab, we’ve been working on a collection of “Journals of useful knowledge, romance, amusement, &c.”, but in actuality they seem to be morality themed newspapers filled with serial stories of ladies in distress and/or fallen women, swashbucklers, highwaymen, and dandies with a side of “Dear Abby”-style courtship and etiquette advice. While mending these papers, we couldn’t help but indulge in a little reading only to discover a few tidbits that might be of interest to conservators and library types.

Continue reading “Conservation insights from the 1870s”

Details Most Curious

As is somewhat typical, we’ve been working on varied collections lately in the Paper Lab, from 18th century English legal documents to 20th century drainage maps of Indiana counties.  Along the way, some fun and interesting details have come up worth photographing and sharing.

 First off is a stain we’re calling the ‘Map Hedgehog’ that was on a mid-20th century map, likely a brown-tone diazotype.

We’re a few days late for St. Valentine’s day, but here’s a wax and shellac seal found on a document dated 1741, England.  William Allen’s seal appears to be a tiny Cupid, including a tiny winged heart flying above and to the left of him.

Within the same collection, we came across some interesting foxing-like marks on a 18th century paper, only they were a well-defined ring structure rather than the diffuse spotting normally associated with the term.  Magnification revealed a tiny blue-green deposit at the center of most, suggesting a copper salt. We’ll likely not know if a copper-based pigment fell into the paper vat, or if errant copper particles developed a patina over time, but the copper has clearly induced oxidation of the paper around it.  Incidentally, the core absorbs UV light very heavily in the center, bounded by a region of orange fluorescence, then the outermost ring absorbs heavily again.

Some other items are this 17th century Frankenstein-esque vellum repair…

…and these two naked chaps diving off a boat in a 19th century engraving of ‘Tynemouth Castle, & Bathing Place.