Posts Tagged ‘paper’

Since last August, I have been pursuing an informal treatment study on batches of Civil War-era documents undergoing washing and deacidification.  Today, I’d like to share some informal, preliminary results.  First, a very cursory overview of some relevant conservation chemistry.

Paper inscribed with iron gall ink, like these Civil War documents, frequently undergoes two types of degradation.  One type is caused by the presence of acid in the paper.  The second type is caused by the presence of iron ions in the ink.  Both types of degradation weaken paper, causing it to discolor, become brittle, and break.

Washing and deacidification treatments address the first problem by neutralizing pH and adding alkaline buffer.  In recent years, chelation treatments have been developed to address the second problem.  These treatments lock up iron ions and make them unable to continue damaging paper. 

I frequently pursue washing and deacidification in the TSLAC lab, and I have been considering introducing a chelation workflow, as well.  To help make that decision, I decided to evaluate the effectiveness of my current treatment by measuring acidity and iron ion presence in the Civil War documents before and after treatment.  Surface pH is measured with an Extech handheld pH meter, and iron ion presence is evaluated with iron gall test papers developed by the ICN conservation program in the Netherlands.  I classify the test paper results from 0 (no iron ions indicated) to 4 (iron ions strongly indicated.)

Given published research, I expected that washing and deacidification would affect paper pH strongly, but would have a negligible impact on iron ion levels.  My preliminary results are surprising.  Average pH increase was more modest than expected: it changed from 4.40 before treatment to 5.56 after, for an average change of 1.16.  Average reduction in iron ion presence was more pronounced than expected:  rankings changed from 1.7 before treatment to 0.4 after, for an average change of -1.3.  Not only does the after-treatment paper remain surprisingly acidic, but it also shows a surprisingly marked reduction in iron ions given that chelation was not pursued. 

These results are very informal, and testing continues monthly.  Myriad explanations can be imagined, not least including inaccuracies inherent in surface pH measurements.  (The unsuitability of destructive sampling is a frequent challenge in conservation research.)  Perhaps additional baths are needed to improve pH.  Perhaps without chelation, the iron ions become more diffuse during washing, creating risks less localized but more pervasive.  I’d be very curious to hear other conservators’ thoughts and interpretations as I consider future washing, deacidification, and chelation treatments.


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One of the most enjoyable things about conservation is the unpredictability and variety of the work.  Today, I’d like to paint a brief portrait of one especially interesting piece of correspondence I recently treated.

Houston Introduction Letter Before Treatment

Sam Houston Introduction Letter - address information visible in upper left.

This 1823 letter is Andrew Jackson’s introduction of Sam Houston to Thomas Jefferson.  My work on the letter coincided with reading H.W. Brands’ Lone Star Nation, an engaging refresher on Texas history even for those who had it drilled into us as schoolchildren.  The timing couldn’t have been better, because Brands’ book puts a very human face on the friendship and mentorship between Jackson and Houston.

Young Houston first met General Jackson while serving under his command in the War of 1812.  Houston followed Jackson into Tennessee politics, becoming a congressman from 1823 – 1827, and governor from 1827 – 1829.  After resigning his governorship when his marriage crumbled in 1829, Houston eventually began his life anew in Texas.  Jackson continued to support him, especially regarding possible US annexation of the region.

Thus this 1823 letter coincides with the 30-year-old Houston’s election to the House of Representatives, a time in which a newly-minted congressman would have eagerly sought new introductions to influential people.  It’s no wonder that Jackson, himself bound for the presidency from 1829 – 1837, would have helped his protégé enter Washington life.  The introduction was timely; Jefferson, already an 80-year-old man in 1823, died in 1826.

The Houston Introduction Letter had some unusual condition issues when it appeared in the lab.  At some point in the past, the letter had been cut into 15 separate pieces, primarily along pre-existing fold lines.  These sections had then been adhered to thin pieces of silk, as was a past preservation practice.  Strangely, small gaps had been left inbetween the cut sections, leaving a grid-like appearance.  Investigation revealed the lining had been adhered with a combination of water-soluble paste and non-archival white glue, much like commercially marketed Elmer’s (see previous entry, “Problem Solving in Paper Conservation.”)

Sam Houston Introduction Letter Before Treatment

Transmitted light shows gaps between cut sections.

It’s impossible to say where, when, or why these previous steps were taken.  They might have happened even before our institution acquired the document.  However, they highlight the importance of reversibility, a central tenet of modern conservation practice.  Because of items like the Houston Introduction Letter, we know that current practice may not remain best practice forever, and we strive to learn from these past mistakes.  Accordingly, ethical conservation treatments comprise changes that can be undone in order to minimize their permanent impact on historical items.
Sam Houston Introduction Letter During Treatment

Mending cut pieces together after removing silk lining.

During treatment, I removed the silk lining, de-acidified the paper, and mended the pieces back together, closing the distracting gaps.  Age and wear have rendered those gaps still partially visible, but overall the treatment improved legibility and reduced visual disturbance.  And, if a future custodian finds that those cuts were historically important (for example, if Jackson had made the cuts himself,) my mends can be reversed and the letter returned to pieces.

Sam Houston Introduction Letter After Treatment

After treatment, the gaps have been closed as possible.

Here’s to a long life for this document of a fascinating confluence of people.

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When I talk to new acquaintances about conservation, I receive an alarming number of immediate comparisons with the National Treasure films, capers that blend American history, conspiracy theories, and Hollywood glitter.  I assure these acquaintances and all current readers that these movies have very little in common with the field of conservation.  But in the spirit of adventure films, I’ll begin today’s post with a quote from the fictional, swashbuckling archaeologist Indiana Jones:

“Snakes.  I hate snakes.”

Why start here?  Because Jones’ longstanding antipathy toward his slithering nemeses parallels my professional feelings about an increasingly common foe: the white glue commercially known as Elmer’s.

For repair purposes, archives typically use water-soluble, reversible adhesives like wheat starch paste.  These adhesives are ideal because they allow previous repairs to be undone when needed, such as removing a silk lining from a paper document.  Reversibility is a central concept in modern conservation, but this wasn’t always the case.  Items that were repaired many years ago, or were repaired by dealers or collectors, were often subjected to whatever materials were on hand.

Lately, I’ve encountered a number of documents lined with silk and a combination of paste and white glue.  At first glance, these documents give no cause for alarm.  But once placed in a bath, the linings remain stubbornly adhered in tiny spots all over the document.  Closer examination then reveals small, milky-white spots of glue, swelled by the water, but not fully reversed.

What’s a conservator to do?  Simply put, get creative and use chemistry.  We know that Elmer’s glue, and white glue in general, is much like the common bookbinding adhesive PVA.  And we know that a Teas chart is a tool that maps various solvents according to their solubility parameters.  Let’s find a Teas chart for PVA, and then, through careful testing, let’s see if any of the solvents effective on PVA will work on our white glue.  Bingo: ethyl acetate.

Ethyl acetate seems to work best when the white glue has already been swelled with water.  It evaporates quickly, so it requires quick, localized work.  But I’ve found it to be quite helpful in removing linings and reducing residual adhesive afterwards.  Treated items receive a final water bath to flush any remaining solvent.  I’d be very curious to hear from other paper conservators any experiences, thoughts, or concerns about using ethyl acetate in this way.

One last personal observation on white glue: it only seems to appear on high-profile treatments involving especially famous or valuable items.  And it appears on these items more regularly than even Murphy’s Law would dictate.  My theory is that these highly valued items have been highly valued for many years, and as a result, their past treatments were probably designed to be extra strong.  If someone incorrectly thought that a water-soluble adhesive might be a weak adhesive, then perhaps that person might have added some white glue to their paste for good measure.

Or perhaps I just have bad luck. I’ll watch out for snakes.

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A brief diversion today, from paper conservation into printmaking and its descendents.

Those with an interest in graphic arts may realize that the ways of producing images are as varied as the ways of interpreting them.  One historical method of creating book illustrations and fine art prints is engraving.  In an engraving, an artist uses a fine, sharp stylus to carve tiny lines into a metal plate.  To print the image, ink is spread into the carved lines and the plate is tightly squeezed onto paper, leaving a positive image of the carved-out areas on the plate.  It’s often said that sculptors make excellent printmakers because of the sculptural process of creating the printing plate.

This engraved image shows how fine lines rendered in ink allow control over grayscale.
Engraving Detail
Detail from the above engraving.

Today, I want to share an ingenious adaptation of engraving in the photographic world, in which light (or shadow) replaces ink.  During Paris’ artistically rich interwar period, Russian / French engraver Alexandre Alexeieff and his American partner / wife Claire Parker invented an image production device called the pinboard.  The pinboard consisted of a fine mesh pulled taut on a vertical square frame.  Tiny metal pins were inserted in the interstices of the mesh, creating a dense surface of 100 pins per square centimeter (that’s right, one fragile pin per millimeter.)  Light was then cast across the front of the mesh at an oblique angle.  As each pin was pushed through the front of the mesh, it cast a shadow whose length could be controlled by the length of the exposed pin.  One pin’s shadow created a mark equivalent to one engraved line.  Just like in engraving, the size and density of the resulting lines allowed for detailed control over grayscale.  A pair of artists working on both sides of the pinboard could use a variety of tools to sculpt their desired image into the dense cluster of pins, which Alexeieff described as velvet-like.  A photograph taken of the resulting pinboard image would yield results much like an engraved print.

Alexeieff and Parker took their process a step farther by taking multiple, successive exposures of pinboard images to create pinboard animations.  Their work was painstaking and deeply detailed; the first animation lasted eight minutes and took two years to create.  Only six full pinboard animations were created in their lifetime, bookended by settings of the music of Modest Mussorgsky; their first in 1933 to the symphonic poem Night on Bald Mountain, and their last in 1972 & 1980, to the first half of Pictures at an Exhibition. 

Below is an excerpt from Alexeieff and Parker’s 1963 adaptation of Gogol’s The Nose (from Facets Video.)  Note that the work looks like an animated engraving.  Note also that each line in each still image was generated by the shadow of one tiny pin.

Alexeieff and Parker’s pinboard is a fascinating interpretation of print concepts in the photographic world, and an example of how image production methods evolve incrementally over time.  I stumbled across this amazing work by way of a chance DVD rental, a testament to the value of browsing your local library or video store rather than relying solely on the recommendations of your favorite online provider.

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Archival Serendipity

As I gradually de-silk, deacidify, mend, and sleeve our collection of Confederate muster rolls, I receive periodic inquiries from the reading room staff as to whether work on a particular requested document is completed.  Untreated muster rolls are not available to researchers due to their extremely fragile condition.

This week, I was surprised to receive an inquiry about a muster roll whose treatment I had just completed three days earlier.  I recognized this particular muster roll by number right away for several reasons.  First, it had arrived in the lab in nine separate pieces and had been reassembled into four complete sheets, one a giant 32.5” x 42.5”!  Beyond the physical condition, I also immediately noticed that this muster roll was filled with Hispanic surnames, something I’d never observed in other similar documents.  Not only was I excited that such recently completed work should be requested by a researcher, but I also hoped to potentially learn a little more about this unusual document. 

The researcher told us that this muster roll represented a unique intersection of Civil War and Tejano history.  When the Civil War broke out, many Tejanos did not support the Confederacy, and they lost land and status.  By contrast, the prominent family of Santos Benavides in Laredo allied themselves with the Confederacy.  Benavides took his staff and servants into battle, and their names are listed on the muster roll.  Benavides eventually became a colonel, the highest ranking Tejano in the Confederate Army, and participated in several significant battles.  Far from encountering ill fortune during the war, Benavides, the son of Laredo’s founder, remained a major landowner and political figure in Laredo until his death in 1891. 

How fortunate to learn more about this unusual document, and how fortunate the timing of the research and conservation work!  Many thanks to our researcher for taking the time to talk about Benavides’ story.  I look forward a forthcoming journal article on the topic.

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Some of you, especially the conservators in the audience, may be aware of the perils of letterpress copying books.  These books are the products of a 19th- and early 20th-century office duplication technology.  In this process, an original manuscript was created with special ink, laid next to a blank, dampened, translucent copy page, and pressed together in a copy press.  The result was a mirror-image copy, which was read through the opposite side of the translucent paper.  For more on this process, see recent work presented by Beth Antoine at the American Institute for Conservation 2011 annual meeting, or Barbara Rhodes’ 1999 publication Before Photocopying: The Art and History of Mechanical Copying 1780 – 1938.

copy press

Many copy presses, like this one, have been repurposed as small book presses in binderies and conservation labs.

The inks and papers required by letterpress technology produced documents that have many physical problems today.  The fragile papers wrinkle and tear easily, and often incur severe damage from ink corrosion.  To further complicate matters, these materials can be seriously damaged by water, rendering many water-based conservation treatments off limits.

For a copying book in the lab this month, I improvised a treatment method that worked satisfactorily well.  I needed to mend several copying book leaves that were severely wrinkled and torn due to ink degradation and research use.  I skipped traditional humidification and achieved moderately successful results flattening with weight alone.  But the problem of holding the translucent tissue flat for mending still seemed to require more hands than I have.  To address this problem, I used the suction table. 

mending on suction table

Mending with heat-set tissue on the suction table.

By drawing gentle suction under the item, I was able to arrange it flat and then have both hands free to apply heat-set tissue mends with a tacking iron.  This method allowed for quick application of mends and hinges for re-securing the pages in their binding.

Question: Is this the most beautiful, perfect, and complete conservation treatment ever devised?

Answer: Definitely not!  The mends are visible on the translucent paper.  This is a stabilization treatment only; other steps would be required to arrest degradation processes inherent in the copybook materials.  Due to the paper’s warping over time, some compromises between legibility and flatness are required during mending.  And the treatment requires leaves to be loose from their binding.  (Several of the leaves in this treatment were already loose; the remaining ones were removed and re-hinged after treatment.  This was quicker and likely less damaging than working in situ.) 

But consider the following: archives often have thousands of these letterpress copying books in their collections, all in similar states of need.  Conservators must develop efficient solutions that make sense within the scope of the problem.  This copying book may not be a thing of beauty, but it is stabilized for use, and that makes all the difference for the next researcher.


copying book

Copying book after treatment, open to a mended page signed by Texas Governor Pendleton Murrah (1863-65.)



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An ongoing project here at TSLAC is the treatment of our large collection of Confederate muster rolls.  These documents provide a fascinating snapshot of men enlisting in the Confederate army, often stating their age, hometown, and personal supplies brought into service.  The muster rolls come in a wide variety of shapes and sizes, with myriad paper, media, and condition issues.  Specifically, I’ve noticed one unusual type of paper that composes perhaps 10% of the collection.  An example of this dark brown paper is below:

Muster roll, silked, before treatment.

Muster roll, silked, before treatment.

In my mind, I’ve come to refer to this as “barn floor paper,” because it would appear to be made from sweepings off the barn floor.  Given the stresses and disruptions in manufacturing in the Confederacy, this isn’t so difficult to imagine.  A close-up may reveal more detail:

Muster roll, detail, during treatment.

Muster roll, detail, during treatment.

The paper is very coarse, with a variety of fibers visible throughout.  It is poorly sized, if at all, which creates challenges in removing existing mends without disturbing the fibers.  After treatment, wash water is a deep, molasses color, though the color of the paper itself remains quite dark.

Muster roll, close-up on heading "Pay Roll," during treatment
Muster roll, close-up on heading “Pay Roll,” during treatment.

Do any readers have knowledge of or experience with this paper?  Do you know what it was made with, or have your observed it in other collections?  I’m curious to know whether its homely composition reflects difficulties in economics and supply chains in the Confederacy, as I imagine.  Or, perhaps this paper was made this way quite intentionally, for a particular purpose.  As with so many record-keeping supplies, I’d argue that purpose definitely wasn’t preservation.

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