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Archive for the ‘Conservation’ Category

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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TSLAC Conservation has recently been working on a collection of 89 19th century Texas Supreme Court dockets.  These volumes document state Supreme Court proceedings and are frequently accessed by staff and patrons. The large number of items requires a blend of collections conservation and single-item treatment strategies.  Prioritizing collections issues has quickly improved access while freeing subsequent time for single-item treatment.

Texas Supreme Court dockets (foreground.)  The yellow color in these photographs comes from ultraviolet filtering in collections storage.

Texas Supreme Court dockets (foreground.) The yellow color in these photographs comes from ultraviolet filtering in collections storage.

First, a preliminary survey was conducted to characterize the oversize ledgers and classify them by severity of condition issues.  Then, collections stabilization procedures were streamlined to take place primarily within collections storage.  Once this is complete, severely damaged items will be targeted for full treatment in the conservation lab.  This workflow has enabled efficient treatment of the greatest number of items and flexible accommodation of other ongoing lab projects.

Portable treatment station in collections storage.

Portable treatment station in collections storage.

The project has presented several challenges.  The time-intensive demands of conservation documentation must be balanced with the pace of work required in a collections-level project.  This highlights the tension between product and process in an archives setting.  Further, efficiency-minded, single-item treatment techniques must be developed for oversize account books. TSLAC Conservation hopes to discuss the project’s challenges, techniques, and successes at the 2017 American Institute of Conservation annual meeting next year.

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This month, TSLAC Conservation highlights our volunteers. With their help, we are preparing 19th century State Supreme Court case files for digitization and improved researcher access.

Legal documents like the case files were typically stored in tri-folded packets and tightly sandwiched into drawers. After many years, the paper strongly retains its folds, making physical access very difficult. A series of grants from the Texas Historical Foundation has enabled TSLAC to address these documents’ physical condition and scan them for digital access.

Thick, folded packets present obstacles to researcher access.

Thick, folded packets present obstacles to researcher access.

TSLAC archivists first humidify and flatten the packets. For many case files, this is all the work that is required. Archivists then earmark any flattened case files in need of conservation treatment. That’s where our conservation volunteers come in.

Anne selects a flattened case file for conservation treatment.

Anne selects a flattened case file for conservation treatment.

Volunteers Anne and Lidia carefully separate case file packets adhered at the top with animal hide glue. They use a methyl cellulose poultice to soften the glue, release the leaves, and remove remaining adhesive. Some packets have two adhered leaves; some have 70! Anne and Lidia also mend badly damaged leaves with Japanese tissue and reversible wheat starch paste. The resulting, stabilized leaves are ready for reading room access and for scanning.

Lidia applies a methyl cellulose poultice to a previously water-damaged case file.

Lidia applies a methyl cellulose poultice to a previously water-damaged case file.

TSLAC thanks our volunteers for their hard work and dedication toward making these documents accessible!

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