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Archive for the ‘Conservation’ Category

Recently TSLAC Conservation has been diversifying our paper mending capabilities with heat-set and remoistenable tissues.  These tissues can offer several advantages, including decreased working time and lessened exposure to water.  Such advantages are key as we prepare many items for the Sam Houston Regional Library and Research Center’s redesigned exhibit space, opening later this year.

A particularly useful heat-set tissue recipe comes from the National Archives and Records Administration (NARA.)  The recipe, presented at the 2015 meeting of the American Institute for Conservation, features an adhesive blend of acrylic Avanse and Plextol products mixed with water.  The adhesive can be cast on various weights of tissue, dried, and quickly applied with a tacking iron.  The tissue is reversible in ethanol and requires no water for use.  It is ideal for manuscripts with iron gall ink that are not otherwise undergoing aqueous treatment.  For these documents, minimizing water exposure minimizes the risk that damaging iron ions will migrate through the paper, thus requiring more intensive intervention.

Applying heat-set tissue with a tacking iron to a manuscript with iron gall ink.

Applying heat-set tissue with a tacking iron to a manuscript with iron gall ink.

Though mending with wheat starch paste is still the preferred standard, we have found the NARA heat-set tissue to be a useful alternative for specific applications.  NARA artificial aging tests indicated that optical brighteners in Avanse do not migrate into mended documents.  However, we will remain alert for future testing on this issue, as well as others relevant to the long-term behavior of acrylic-based adhesives in paper mending.

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TSLAC Conservation recently attended the 45th annual meeting of the American Institute for Conservation (AIC.)  The meeting’s theme, “Treatment 2017: Innovation in Conservation and Collection Care,” was embodied in several sub-themes, including a focus on conservation documentation.  Though documentation may not be the exciting part of treatment, it is an ethical necessity to record how physical intervention may change the nature of a historical artifact to prolong its life.

In her talk, “That Poor Cousin of Treatment: Documentation and Possibilities for Simple Innovation,” Cybele Tom of the Art Institute of Chicago presented a case study in thorough documentation as multiple conservators treated one object over many years.  She found that documentation of past treatment greatly influences current treatment decisions, and she considered detailed documentation as a “love letter to a future conservator.”  For highest accuracy, documentation might include both quantitative, objective measurements and qualitative, journal-style musings on decision making. However, these idealized practices require judicious application.  In a higher-volume, collections-based workflow like TSLAC’s, a different approach is needed.

More representative of TSLAC’s workflow was the talk “Medium Rare: An Innovative Treatment Approach to the Space between Special and General Collections.”  Quinn Ferris of the University of Illinois at Urbana Champaign discussed issues familiar to many conservators who work with materials that fall somewhere between general collections and special collections.  Documentation presents a special challenge for these materials: it should be careful and methodical, while still promoting quick turnaround.

TSLAC’s solution is to create written documentation for all items using a check-box-based database, which provides a searchable, controlled vocabulary.  Additional descriptive fields allow customization and qualitative musings like those advocated by Ms. Tom.  We pursue photographic documentation only for treatments that are especially invasive or that involve items that are especially unique.  As seen at the AIC meeting, balanced solutions like ours are pursued in other, similar collections.

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May is Preservation Month, and here at TSLAC we’re celebrating by launching several new environmental monitors throughout our building.  Providing a stable environment is one of the best steps you can take toward safeguarding collections.  By controlling temperature and relative humidity, you can slow the clock on natural aging processes and often avoid conservation treatment altogether.

How does environment matter from a conservation perspective?  Simply put, it impacts materials’ mechanical and chemical stability.  Mechanical damage may occur when fluctuations in temperature and relative humidity cause materials to expand or contract.  Rapid cycling of temperature and moisture is especially problematic.  This can lead to cracks, tears, and breaks.  One household example of mechanical damage can occur when pouring very hot water into a cold glass causes the glass to break.  This dramatic damage can also occur gradually over time if archival materials are improperly stored.

Mechanical damage: transcription disc.

Mechanical damage is one factor at work in the pictured transcription discs. The discs’ outer coating (cellulose acetate plastic) and inner core (glass) have reacted to their storage environment differently, causing severe cracks and losses. (Photo by Steve Kantner.)

Chemical damage occurs when materials change or weaken at the molecular level.  Chemical damage, in its many forms, generally speeds up in warmer, wetter conditions.  Without sufficient heat or moisture, some deterioration processes may never start.  Familiar examples of chemical damage driven by environmental conditions include yellow, brittle paper and silver mirroring in black and white photographs.  In archives, a particular concern is iron gall corrosion, the process by which historical ink can eat through paper.

Chemical damage: iron gall ink

Chemical degradation has caused the iron gall ink in this document to weaken its paper support. As a result, brown halos appear around heavily-inked areas, and losses are visible in the large letter “G”.

Archival environmental standards for paper-based materials are 45 – 55% RH, 65 – 72 degrees Fahrenheit.  While it’s OK for these levels to drift gradually across seasons, short-term fluctuations should be minimized.  Remember these environmental impacts as you safeguard your treasures.

 

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This month we highlight an early 1900s family photograph from the Callender, Goldsmith, and Cox family papers held at the Sam Houston Regional Library and Research Center in Liberty, TX.  The subject of the photo, Russell Goldsmith, was a bookkeeper at Gulf Oil Refinery in Port Arthur, TX.  Given its age and drawing-like appearance, this hand-colored image may be a gum bichromate print.  The 11” x 8.5” photograph is mounted on curved board, which was popular in early 20th-century family portraiture.  Boards were shaped into a dome with steam and custom framed beneath curved glass.  At some previous time, this photograph was separated from its frame and its vulnerable dome shape was broken.

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Domed photograph with breaks, abrasions, creases, and previous repairs (graphite retouching.)

The goal for this treatment was to stabilize the item for storage and possible display within the skill set available to a book and paper conservator.  Photograph conservation is a specialized field.  It is hoped that the reversible elements of this treatment would allow work by a photo conservator at a later date if required.

After testing for media solubility, small amounts of thick wheat starch paste were worked into the exposed, broken board edges.  Broken segments were aligned and Japanese tissue was adhered on the back of the item.  This process required working in steps from the front and the back, while supporting the item’s curved shape.  Even this iterative approach required compromises of alignment between the image area and the board’s convex shape.  After many years of separation and changing environmental conditions, it is likely that the board pieces have drifted from their original shape.

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Supporting the curved shape while mending.

The fragile nature of these repairs required careful housing for protection.  The domed image was centered on mat board with pH-neutral bulk surgical cotton and a buffer sheet of Japanese tissue beneath.  The item was then pressure-mounted to the backing board with window mats.  A window mat cut slightly smaller than the image was bulked with three layers of archival corrugated board to accommodate the depth of the curve.  Finally, a top window mat and cover mat were attached.

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Corrugated sink mat edges being covered with paper (outside edges complete.)

Abrasions in the image area along the broken edges were inpainted with acrylic paint and methyl cellulose, with an eye toward minimizing the visual impact of the damage.  As the least reversible step in this treatment, inpainting presented an ethical dilemma.  The choice was made due to the distracting nature of the cracks and the low probability of future re-treatment.  The matted photograph will be stored in an artifact box.  It is suitable for viewing and display as matted.

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Reassembled and inpainted domed photo in sink mat.

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The Address on African Slave Trade in Houston, TX is a rare 1859 pamphlet documenting a speech given by Peter Gray, an attorney, judge, and legislator in early Texas.  The item arrived in the conservation lab whip-stitched into an aging pamphlet binder.  The pamphlet’s leaves were silked, a previous preservation treatment that has now proved problematic.  Partly as a result of the silking, many of the acidic paper leaves were torn and detached, putting them at risk for further damage and loss during use.  The acidic pamphlet binder was also causing the leaves to become more brown and brittle over time.

Before treatment: silked, acidic, broken leaves.

Before treatment: silked, acidic, broken leaves.

Critical details about the pamphlet’s structure were documented during disbinding.  The pamphlet’s leaves were folded into two sections, but typical, pamphlet-style sewing was not observed.  Instead, the item appeared to have been side-sewn several times in the past.  This restrictive sewing method is not viable for fragile, brittle paper.

During treatment: mending tears

During treatment: mending tears

Two treatment options were considered.  One approach was to re-create a modified pamphlet: rebuild broken folds, punch new sewing holes, and sew with a pamphlet stitch.  Another option was to enclose each leaf in a Mylar sleeve and bind the sleeves with stiff posts.  We chose the first, more conservative option, which preserves more of the item’s original structure.  After treatment, we judged that the paper would be sufficiently strong to tolerate gentle flexing and anticipated use.

After treatment: pamphlet is sewn into a paper case typical of its period.

After treatment: pamphlet is sewn into a paper case typical of its period.

Leaves were washed, deacidified, desilked, and resized with gelatin.  Then, the paper was mended, losses were filled, and the pamphlet was rebuilt as described above.  Replacing the whip-stitching with typical pamphlet sewing allows an unrestricted opening that will minimize future damage.  The completed pamphlet was sewn into a paper case and housed in an acid-free pamphlet binder for safe storage.

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TSLAC Conservation recently performed treatment on an 1825 travelogue, The Modern Traveler: a Popular Description, Geographical, Historical, and Topographical of the Various Countries of the Globe: Mexico and Guatemala, by Josiah Conder.  The small volume (15 x 9.5 cm) was initially selected for a short-term exhibit and then for more thorough treatment.

Volume with fold-out map.

Volume with fold-out map.

The volume was an appealing exhibit item given its small, fold-out map of Mexico.  Unfortunately, both the map and the front board of the volume were detached.  Due to the informal and short-term nature of the initial exhibit, condition issues were initially addressed by creating a temporary support from archival matboard for the open front cover and map.

Volume with reattached board.

Volume with reattached board.

After the exhibit, a more permanent solution was sought.  The detached map and adjoining leaf were re-hinged into the volume with Japanese tissue.  The front board was then reattached with Japanese tissue toned to match the covering leather.  This volume is now stable for patron use and for storage in the stacks.

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Though our conservation lab at TSLAC focuses primarily on books and paper, we also care for the non-paper-based archival items found in our collections.  This month, we created a housing for an undated photographic glass plate negative from the Sam Houston Regional Library and Research Center in Liberty, TX.

A glass plate negative consists of photographic emulsion cast on a glass plate.  The negative image on the plate is later developed into a photographic print.  Glass makes these negatives very fragile.  When they break, their fractured edges begin to abrade one other, causing more damage to the glass and the media.

Broken glass plate negative in modified sink mat.

Broken glass plate negative in modified sink mat.

Our housing is based on a design from the National Archives.  The broken negative is stored in a covered sink mat for protection.  Small spacers separate the broken pieces to minimize abrasion.  The mat is stored flat in a box with a warning label regarding careful handling.

Detail of spacers separating broken fragments.

Detail of spacers separating broken fragments.

The outer mat edges are hinged, allowing the item to be removed from its housing as needed.  However, future removal should be rare, since the image was scanned before treatment.

Scanned image from glass plate negative.

Scanned image from glass plate negative.

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