Causes of Deterioration
Tapa is constructed of organic fibers, therefore susceptible to damage from insects, mold, acidic pollutants, extreme heat, light and dust. You should begin by examining your tapa and the area where it is stored or exhibited to see if any of the following problems can be eliminated.
Bugs are a major source of damage to tapa. Insects will sometimes eat tapa fibers themselves as well as the starchy paste often used during manufacture. The tapa should be examined periodically for the presence of holes or insect pellets or droppings. If an infestation is discovered, the tapa should be bagged and the DAC should be contacted regarding the procedure for freeze sterilization. It is generally not recommended to use chemical fumigants to get rid of insects.
Relative humidity is a measure of how much moisture is in the air. Tapa has the ability to absorb and desorb moisture as the humidity goes up and down. For this reason, very low humidity is not good for tapa as it will cause the fibers to become brittle. Constant swings in humidity are harmful because, in time, break-down and weakening of the fibers will occur. Perhaps the biggest problem in Hawaii is the growth of mold due to the presence of excess moisture in the air. Some types of mold can grow with humidity as low as 65%. As our humidity in Hawaii is often above this, steps should be taken at home to avoid mold growth.
Mold is a problem with tapa because it is visually disfiguring and will weaken the fibers. Mold grows best with high humidity, lack of circulation, and the presence of food such as dust or oils to grow on. Mold can be avoided by keeping your tapa away from damper rooms such as bathrooms, and away from areas that may have had mold problems in the past. Air circulation in the room where tapa is kept can be increased by running fans and by routinely airing out closets and storage boxes.
If mold is found, the tapa should be spread out onto a clean work surface and the fluffy mold growths lifted with a dry, soft, natural bristle paint brush. A vacuum nozzle should be carefully held above the area being brushed to collect the mold as it is lifted. The nozzle should not be allowed to contact the tapa surface directly. Be sure to wear a protective dust mask and latex gloves when handling moldy tapa. After cleaning, the tapa should be allowed to air out for a short while then should be returned to a dryer area than where it had been when it began to grow mold.
Tapa can be damaged when placed in contact with materials that give off acidic vapors. Many common household items such as wood, cardboard, paper towels, pvc piping and common tissue contain acidic materials that in time will cause discoloration and weakening of the fibers. Custom made archival materials such as mat board, storage boxes tissue and paper are available which do not contain acids. When choosing archival storage materials, choose those that are both acid free and lignin-free. For storage purposes, unbleached cotton muslin, white cotton or polyester/cotton blend sheets and towels can also be used to protect tapa as these materials do not contain acids. All of these materials should be well washed before they are used to remove sizing and old detergent.
The energy in light can cause damage to tapa by weakening the fibers and by fading colors. Some types of light such as sunlight and light from fluorescent bulbs contain higher energy and are therefore more damaging than incandescent light. To lessen the damage caused by light, stored tapa should always be kept in the dark. Exhibited tapa should be kept away from direct sunlight and bright spot lights. Ultraviolet filtering acrylic sheeting such as plexiglass can be used with framed tapa to help filter out the more damaging high energy ultraviolet light.
Dust can damage tapa by causing unsightly stains and by attracting insects and mold. Tapa should be kept dust free by properly storing in a box or by protecting in a shadowbox frame with glass or plexiglass. Dust on the surface of tapa can be removed by laying the tapa out on a clean, dry surface such as a dining table. A section of clean nylon window screening should be laid over the tapa and a vacuum used to clean through the screening. The screening keeps the vaccum from sucking up loose pieces or grabbing at the tapa. Reference and Acknowledgement This article and other articles included in the series of (Conserving Hawaiian Kapa) is from a handout written by the Pacific Regional Conservation Center of Bishop Museum, now known as the Department of Art Conservation. If you find you have more questions about tapa conservation, you can contact the center at www.bishopmuseum.org/research/conservation.html.