Using Decorative Fabrics Inside Exhibit Cases
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The dyes and finishes applied to many fabrics make them inappropriate for direct contact with collection materials. Only certain fabrics with a 100% pure fiber content and water stable dyes can be selected.
What are the principle conservation concerns when selecting fabrics for case interiors?
Experience has shown that many fabrics are inappropriate for use as case liners. Decorative textile fabrics used within exhibit cases for aesthetic or interpretive reasons must therefore meet conservation criteria. The principle concerns are the fiber type, additives, dye stability and transfer, and surface characteristics of the finished fabric.
- Wool is a sulfur-containing protein, which upon degradation, emits hydrogen sulfide gases which are corrosive to metals, especially silver.
- Cellulose acetate fibers can degrade to produce acetic acid.
- Polyvinyl chloride-containing fibers, part of the group of fibers called vinyls, produce volatile hydrogen chloride when exposed to heat and light.
- Volatile organic compounds (VOCs) are emitted by some fibers, like wood
- Adhesive and/or foam backings on hook and loop material (such as Velcro) can emit harmful VOCs into the environment of the case. Only hook and loop materials without these features should be employed.
- Sizing additives are glutinous materials such as starch or acrylic acid derivatives (resins) added to fill the pores or surfaces of the yarn or threads in order to withstand the abrasive forces of the weaving or machining process. Sizing can react with display objects.
- Ammonia and mercerization treatments produce fabrics with very different characteristics. Residual chemicals can cause deterioration problems.
- Permanent press/fire retardant treatments use acidic chemicals, like urea formaldehyde,and a variety of other chemicals (disodium phosphate, etc.) which degrade readily and become volatile.
- Carpets often include rubber, foams or adhesives which make them unsuitable for the enclosed environment of a case.
- Dyes can sometimes bleed or rub off onto materials which come into contact with them. This dye transfer can occur through dry abrasion of the surface or when the fabric is exposed to water or solvents. Very unstable dyes can become soluble during high humidity and leach into surrounding material.
- Direct dyes for cotton and linen using sodium chloride or sodium sulfate assists should be avoided.
- Choosing a light-fast dye prevents premature replacement of the material.
- Delicate surfaces can be damaged by abrasive fabrics and knapps.
- The fabric can aid or inhibit the physical stability of objects; knots or imperfections in the knapp can prevent an object from resting securely on a surface. Velveteen and other smooth-knapped fabrics can help hold an object in place, for example when it is placed on a sloping surface
- Carpets trap dust and insects and can provide an uneven and abrasive surface for artifacts.
How can textile materials be safely incorporated into a case?
Textile fabrics are extremely variable. It is especially important that a fabric used as a case lining be researched and tested, both for volatile outgassing and for damage that can occur from direct contact. In addition to the Oddy test examines dyes for water solubility by blotting a piece of the wetted fabric with white toweling, or by immersing sample in water for 15 minutes, then blotting. There are a few practical measures that make the use of fabric in a display case safer.
- Use the safest types of fabrics: Unfinished cotton, linen, silk and synthetic fabrics are good choices.
- Unbleached cotton, linen, silk should not contain any foreign matter or processing chemicals.
- Synthetic materials have very low water absorbency or retention, and low abrasion qualities.
- Polyester offers strength, abrasion resistance, and resistance to tearing.
- Nylon (polyamides) have similar characteristics to polyester.
- Acrylic, part of the group of fibers called vinyls or acrylonitrile, is chemically resistant and strong.
- Isolate objects from direct contact: Objects should only come into contact with stable materials. Use polyethylene or polyester sheeting, or other inert materials as a barrier between the object and decorative fabrics of uncertain stability.
- Prepare the fabric for use: Fabrics should be washed in a neutral detergent to remove excess dyes and finishes, and to preshrink fabrics; to remove all residual dye, wash until the water runs clear.
- Avoid using adhesive: Attach fabric mechanically; sewing is the best option. Rust-proof staples, tacks pins, or archival-quality self-adhering tape can also be used.
Mention of a product, manufacturer, or supplier by name in this publication is for information only and does not constitute an endorsement of that product or supplier by the National Park Service. Listed materials have been used successfully in past applications. It is suggested that readers also seek alternate product and vendor information to assess the full range of available supplies and equipment.
Fabrics Free of Surface Finishes
- Whaley's (Bradford)
Polyester Felts and Knapped Fabrics
- Benchmark - 100% polyester felt with or without acrylic adhesive backing
- Melded Fabrics - Prelude felted, Front Runner knapped fabrics
Hook and Loop Fastener Compatible Fabrics
- Showtime Fabric or Gilford Fabric (100%polyester; these fabrics are free of the low quality foam backing; available in different colors)