The Paintings conservator is responsible for the care of more than 380 paintings in the Winterthur collection, as well as their frames and painted surfaces on objects such as furniture and clock dials. Paintings conservators address structural problems such as torn or deteriorated canvas or stretchers that cause distortion and loss of the paints and varnishes applied to them. Paint on any substrate (canvas, wood, or metal) may begin to flake due to physical damage, corrosion, or shrinking and swelling in the substrate caused by unstable relative humidity. Wood and fabrics such as canvas absorb and release moisture as the relative humidity fluctuates, which results in dimensional changes. Because the paint layer absorbs moisture at a different rate, it cannot change with the substrate, causing the paint to flake. Varnishes and coatings applied to the surface age and darken with time and may require cleaning or removal and replacement.

Visually and structurally, frames are an integral part of paintings because they provide protection and the means to hang a painting. Traditional frames are composed of wood, compo (a plaster-like mixture of chalk, glue, resin, and oil) and various gilt and painted finishes that are subject to abrasion and physical damage that causes breakage and loss of decorative elements.

Preventive Conservation

Like other parts of Winterthur’s collection, paintings are maintained at a stable temperature and relative humidity of 50 percent and protected from excessive light that can accelerate aging of varnish and fading of pigments. Proper framing requires a backing board to protect the canvas and secure hardware to ensure safe hanging.

Textile conservators at Winterthur are responsible for about 20,000 objects such as window treatments, bed curtains, rugs, costumes, quilts and coverlets, needlework, and upholstery. Damage to textiles comes from many sources. Unstable environmental conditions that cause mold and exposure to excessive light weaken and discolor textile fibers and fade dyes and colorants. Abrasive, acidic soil from the environment that becomes embedded in the fibers also weakens and disfigures the textile. Stains and wear from past usage contribute to deterioration. Some dyes and finishes used in the production of textiles are inherently unstable and may case serious damage. Textile conservators support and stabilize the structure of textiles while reducing stains and degradation wherever possible.

Preventive Conservation

Winterthur’s textiles are stored in stable environmental conditions using acid-free archival quality tissues, boxes, and fabrics. To prevent creases that cause localized damage to the fibers, textiles are rolled or padded with acid-free tissue. Textiles on open exhibit are cleaned regularly by careful low-suction vacuuming to remove dust. Lighting specialists are especially vigilant in lighting textiles and keep the levels very low.  If a textile becomes too weak to remain on exhibit, it is retired to the study collection and replaced with a textile in better condition or a reproduction fabric. Textile conservators also work with furniture conservators to preserve existing upholstery fabrics or replace them with reproductions.

The Furniture Conservation Lab cares for and treats about 9,000 pieces of furniture and wooden objects in the collection. Historic surfaces, both transparent and painted, change and deteriorate over time, resulting in crackling, flaking, uneven darkening, fading, blanching, scratches, and stains. Furniture conservators are concerned with both structural and surface issues. Conservators maintain and stabilize the structure of objects that may have been damaged or poorly repaired in the past, that suffered an insect infestation, or were weakened by exposure to water or a poor environment. They balance preserving early surfaces and the history they embody with maintaining an aesthetic appearance that respects the intent of the original maker.

Working with textile conservators, furniture conservators also care for upholstered furniture. They preserve and stabilize existing upholstery structures and show fabrics when they are historically appropriate and in stable condition. When the upholstery is inappropriate and/or the structure or show fabric is too deteriorated, conservators replace it with a non-invasive structure that avoids nailing or tacking into the original wood.

Preventive Conservation

To reduce the risk of damage to its furniture collection, Winterthur maintains a stable environment with an average temperature of 68 degrees to 70 degrees and a relative humidity of 45 percent to 55 percent. A stable relative humidity is especially important to furniture since rapid changes cause different parts of the object to expand and contract at different rates and to different degrees, causing problems such as detached veneers, cracks, and flaking paint. Since insects like the powder post beetle can cause serious damage to wooden objects, preventive conservation aides carefully monitor for evidence of insect activity. Excess light can cause surfaces and upholstery fabrics to fade or darken so exterior windows are modified to reduce ultraviolet and visible light. Wintethur lighting specialists design interior lighting to minimize damage.

Paper conservation cares for almost 5,000 prints and drawings, including some of the most important prints of the early national era by artists such as Peter Pelham and Paul Revere. The collection also includes pastel paintings on paper, early German American fraktur, and paper-based materials such as hat boxes and several rooms of historic wallpaper. Winterthur’s prints and drawings are found on display in museum rooms and on reserve in a large study collection that is a rich resource for scholars in many disciplines. Paper is vulnerable to damage including tears, creases, soiling, overall discoloration, and stains. Exposure to excessive light, heat, and high humidity accelerate its deterioration. Such conditions also threaten images on paper and may cause flaking media, color shifts, or fading of inks and other design materials. Paper objects suffer additional damage in storage or on exhibit when in contact with acidic mats, folders, and boxes. Frames that are too small or that do not provide adequate space between the glazing and the object can also cause damage. Repairs with pressure sensitive tapes and poor-quality adhesives often must be removed to prevent ongoing damage. Paper conservators focus on repairing and supporting the structure of the paper object, reducing discoloration and acidity when appropriate. 

Preventive Conservation

Winterthur’s paper collections are kept in a controlled environment in the museum and a preservation environment of 65 degrees and 45 percent relative humidity in the Maps and Prints study collection. This environment reduces the rate at which paper deteriorates and prevents the growth of mold. All objects are stored in alkaline mats or folders that help protect them during handling and study. A Preservation Housing Specialist ensures that all framing is safe and appropriate for the object.

This conservation lab is responsible for the care of collections in the Winterthur Library. The collections include books, manuscripts, printed ephemera, and photographs. Winterthur’s staff, outside researchers, and graduate students depend on these resources, so maintaining access while preserving the collection is a high priority.  The collection includes 87,000 volumes of current and rare publications; more than 1 million manuscripts, printed ephemera, and photographs in the Joseph Downs Manuscript Collection; and 2,200 linear feet of archives, including manuscripts and archives.

Deterioration of library materials can result from poor environmental conditions, poor storage, and careless handling. High temperature and humidity accelerate chemical reactions that cause paper, photographs, and leather to deteriorate. Contact with poor storage enclosures such as acidic folders, unstable plastic, and corrugated storage boxes cause paper and photographs to weaken, discolor, and fade. Careless handling can cause torn, soiled paper and loose, broken bindings. Papers and leathers were poorly made quickly become brittle and deteriorated.

Preventive conservation

Preventive conservation is especially important for Library collections because the materials need to be used. The library stacks are maintained at 65 degrees and 45 percent relative humidity to extend the life of the collection. Researchers use book supports and other aids to help them handle collections safely. The librarians and conservators work together to provide protective enclosures for damaged collections and those in need of extra protection. Brittle or heavily used material may be reformatted to provide digital copies so the original can be retired except for those scholars who need access to the original.

Rare Books

The collection ranges from 16th-century leather- and vellum-bound books to 19th-century cloth-case bindings and elaborate design books in finely tooled Morocco leather to trade catalogs in paper wrappers. Before 1800, most books were sold in sheets, then bound to the specifications of scattered booksellers and purchasers, so each binding is unique. In the 19th century, publishers began to bind books before they were sold, but often issued the same book in different bindings to appeal to different audiences. Each book and its binding in the collection has a story to tell about its time and place, so conservators repair and reuse original bindings whenever possible.

Thomas Wilson, dancing master, wrote An Analysis of County Dancing (GV1763 W75 S) for publication in London in 1808. In it he notes that “even persons of the meanest capacity” may acquire “a complete knowledge of that rational and polite amusement” and illustrates his instructions with woodcuts. The book was bound in a gold-tooled full-calf binding that afforded excellent protection for the text but succumbed to years of wear. The leather is worn and abraded and both boards are detached. Using toned, hand-made Japanese paper and reversible archival adhesives, the boards were reattached without compromising the original binding.

Object credit: RBR GV1763 W75 S Courtesy, The Winterthur Library: Printed Book and Periodical Collection

Manuscripts and Archives

The manuscript and archives collections contain everything from the daybooks of 18th-century silversmiths to late 19th-century tradecards for sewing machines; from architectural drawings for early 19th-century town houses to rare autochromes of Winterthur’s gardens; from photographs of Shaker communities to the exercise books of school children.

Peggy Clayton, who lived near Halifax, NC,  created her calligraphy mathematics exercise book (Doc 1442) in the 1770s, ornamenting it with pictures of American ships, flags, and patriotic sentiments as well as standard exercises such as addition, subtraction, multiplication, rule of three, and simple and compound interest.  She used the common writing materials of the period — hand-made laid paper, a quill pen and iron gall ink. The folded leaves were sewn into a soft cover composed of a canvas laminated between a heavy outer paper and newsprint on the inside.

The cover is detached from the manuscript and it is soiled, torn and dog-eared from years of use. Except for minor tears, the major problem is the unstable and corrosive iron gall ink.  The acidity and related chemical reactions of the ink weaken and embrittle paper to the point where the paper splits or fragments in areas of heavy application, even when the paper is handled carefully. Research on processes to chemically stabilize the ink are ongoing but not yet ready for application to documents like this. To prevent additional damage, areas of severe corrosion needed reinforcement. Because moisture increases the rate of deterioration, standard mending techniques using water-based adhesives could not be used. Instead, conservators coated a thin, toned Japanese paper with an adhesive activated with ethanol to reinforce damaged area. This material is easily reversible and will not cause additional damage. After treatment, the manuscript returned to storage in climate-controlled stacks were the low relative humidity will slow the deterioration of the ink.

Object credit: Doc 1442 Courtesy, The Winterthur Library: Joseph Downs Collection of Manuscripts and Printed Ephemera

Documentation is part of every conservation assessment or treatment. Photographic documentation—the creation of accurate images—is the core of the process. 

Each object is photographed before conservation treatment to record its condition and visible damage, then photographed after to document repairs. Images usually capture both overall views and details. Photographs may be taken during treatment, especially before inpainting or other forms of compensation. To record damage as accurately as possible, photographs may be taken in both reflected and raking light, which reveals surface texture and planar distortions. Special equipment and procedures are used for highly reflective objects such as silver or large objects like quilts.

Winterthur’s digital image capture and storage follows guidelines set by the American Institute for Conservation. Digital files are processed and stored using the most durable formats and methods available.

Because the energy from fluorescent lamps, visible light, and sunlight causes chemical changes that result in weakening, embrittlement, darkening, or fading of museum objects, conservation lighting is a specialty that is extremely important to their preservation. 

Some materials such as paper and textiles are highly sensitive to light; they are exhibited at 5 footcandles. Materials such as metals and ceramics are safe at higher levels. They can be exhibited at 20 footcandles. Specialists must work within these limitations to light exhibits in a way that complement the objects and allow the public to see them clearly.