Things have been relatively calm in our corner of the blogosphere for several months, so I thought I’d add a post about a treatment I’ve been working on in the Paper Lab. We received five leaves of correspondence from the US History manuscript collection at Lilly Library. The small collection of letters are written in German by Philip Boehm, a Union soldier, to his sister during the Civil War. All have been laminated in a manner that was new to me: it appears a well-meaning, but ultimately misguided person placed each leaf in a plastic3-ring binder pocket protector and then used a domestic iron to melt and seal it all together. The film is perhaps polypropylene or polyvinyl chloride (I didn’t do the testing to confirm).
Most laminations involve a commercial product: either a heat-set or pressure-sensitive adhesive backed film is applied to both sides of a document. Over time, the films can oxidize, turn yellow, and possibly go brittle. The enclosed paper document becomes exposed to this oxidation and hydrolysis and can also become impregnated with the melted plastic or adhesive from the film. Removal generally follows methods associated with pressure sensitive tape removal- the use of solvents to swell or dissolve the film and/or the adhesive deposit. Heat can also be applied in a variety of ways to effect removal.
In this case, a combination of the two approaches is proving effective. Rather than applying heat from above, with a stream of hot air or getting in-between the materials with a heated spatula, I found that heat from below was the most effective.
Here’s the set-up, and another shot of it being used:
A conventional tacking iron that every conservation lab possesses is set to the lowest heat setting and stabilized in a face up position. Using the surface as a mini hotplate, the document is stabilized on the iron with a Casselli spatula in my left hand while I slowly pull the softened film away with the other. In this manner, strips are removed from recto and verso sides. The process takes around 45 minutes.
After film removal, the paper still appears translucent and darkened due to plastic that saturated the fibers. Testing of solvents reveals that an immersion in acetone for about 15 minutes reduces this effect by swelling remaining laminate substances and leaves the paper in a close to original state. Mending tears with tissue and wheat starch paste follows. Humidification and pressing completed the work.
I recently mended and made folders for items in a Lilly Library manuscript collection. The collection contains the papers of Charles A. Halleck, who served in the U.S. Congress from 1934 to 1968. There was nothing unusual about the contents of one particular box, just original drawings of political cartoons and ads regarding the congressman from the mid-thirties. Then I looked a little closer at one of Halleck’s portraits.
The hatching in the illustration looks too good. It looks manufactured, not hand-rendered, but the perimeter of the shaded areas follow the form of brush strokes, just like on Halleck’s inked lapels. I found two other drawings of Halleck with the same perfectly hatched and occasionally crosshatched tones filling out the shadows on his face and neck. Fortunately, the backs of the illustration boards are marked “Craftint Doubletone,” so that’s where I started my search.
The Ohio-based Craftint Manufacturing Company offered Doubletone and a similar paper called Singletone from 1929 until they sold the product to the Ohio Graphic Arts Center, now Grafix. Grafix renamed the product Duoshade and it was available until 2009 when it was determined obsolete in the face of programs like Adobe Illustrator, and discontinued.
Twentieth century reference books and journal articles describe Craftint’s seemingly magical paper as an illustration board with a latent pattern on its surface that, when brushed with a liquid developer provided by the company, appears where desired. In these books, there is no mention of the chemical response in these latent patterns. However, as commercially successful products, I knew there must have been a patent on them.
After some digging, I found an application filed by Henry M. Baker in 1927 and patented in April 1929, the same year that Craftint started offering its product. Baker explains that by developing a silver nitrate image (a pattern of dots or lines) and blanching it with a substance like mercuric chloride to render it undetectable, a sensitized and lightfast image remains dormant until activated with a liquid developer.
Baker does not specify the chemical agent used to redevelop the pattern in his application. However, a patent issued to Carl Maier and William Swaysland in 1930 also listed on Craftint’s July 1948 product catalogue uses a different approach, by which a lead sulfate (lead white) pattern is applied to the paper’s surface and a soluble sulfide is brushed on where desired, turning the lead sulfate to lead sulfide, a dark compound. And if you made a mistake on the paper? Hydrogen peroxide would convert the lead sulfide back to a white compound. Other inventors built off Baker’s initial process, leading to various combinations of chemicals and developers.
A few detail images of Halleck’s inked portraits show the blank, undeveloped surface, the India ink drawing, and the developed pattern. Since these images are on Craftint’s Doubletone paper, there are two different patterns printed on the paper’s surface. Independently, the patterns make up two groups of parallel lines that, when both are activated, appear as crosshatching. A light tone developer makes visible one set of lines. For a darker tone, another developer is applied, but only after work with the light developer is finished.
What made Craftint toned papers so useful for twentieth century graphic artists? The potential to bring out large areas of tone with no more effort than a brush stroke is one of Craftint’s most attractive qualities. Compared to hand-rendered hatching and stippling, the results would be swift and concise, and mistakes were easier to hide via hydrogen peroxide than scraping or masking ink. Other methods of achieving tones and patterns were not always as effective and, in the case of halftone reproduction, not as affordable. Ben Day dots, as they are known now, did not offer the same precision as Craftint’s toned papers and had to be applied one large area at a time and burnished to complete the transfer of pattern, although they were available in a variety of colors. The tonal variety seen on and around Halleck’s mouth would have been difficult to achieve with Ben Day dots. Additionally, Craftint reproduced well at reduced sizes. A proof of Halleck’s ad shows the artist’s rendering reduced to smaller than one-quarter of the original. At such a size, the hatching on the original appears as a smooth, even tone across his face.
This process is very far from magic, though it surely seemed that way for artists. After dipping their brushes in clear liquid, the path of their brushstrokes immediately turned dark as it traveled across the paper. The phenomenon was easy to overdo, leading to images with many toned areas that, when reproduced into small comic strips and magazine ads, turned out cluttered and unclear. Artists commended peers who knew when to stop.
Anderson, Murphy with R.C. Harvey. The Life and Art of Murphy Anderson. North Carolina: TwoMorrows Publishing, 2003.
Baker, Henry M. Camera copy, and method of, and medium for making the same. 1709600, 1929.
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.
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 consolidation. Typically, 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.
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.
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.
We 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.
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.
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.
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.
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.
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!