1Feather creations represent a rich and varied group of objects, almost all of which are composed of feathers joined together with other materials. The feather condition and technical surveys were created in order to determine whether there is any observed relationship between deterioration and the construction of a feather object, its length of time on display, the type of display lighting, and how often the object has traveled. With the help of all of the seminar organizers, these surveys were translated and sent to collections in the U.S., Mexico, and Europe, which display and preserve feather creations. Survey forms were returned that report on about 40 objects by the date of this presentation.
2Survey results are difficult to interpret, because it is almost impossible to know when damage occurred, or to relate damage on a 400 year old object to only its recent care. Surveyors also differed in their expertise in evaluating damage. However, results, which are presented on an attached table, show that caretakers are aware of providing a controlled climate, and of the problem of light damage for feathers. More than half the respondents display feathers at less than 50 lux, or 5 footcandles. Another 6 display their objects at less than 120 lux, or 12 footcandles. However about half of the feather objects have been on display for over a year, often on permanent display for up to 50 years. Since light damage is caused by the intensity of the light multiplied by the time spent illuminated, is extremely challenging to maintain feather creations with daily display illumination. Only a small number of feather objects are displayed under filtered lights to remove damaging energy. The most creative solution was provided by the Landesmuseum in Stuttgart, where an opaque vitrine is displayed with images of the Aztec shields, and a request must be made to a Security Guard to open the vitrine for viewing the originals. Systems currently in use in museums include cloth covers over vitrines that audience members lift for viewing, or electronic sensors that detect the viewers approach before illuminating a case.
3As other seminar participants describe, feathers are made of proteins, water, and oils, related very closely to the composition of wool, hair, horn, and fingernails. Like wool, feathers are susceptible to attack by insects, especially clothes moths. The natural colorants in feathers are referred to as biological pigments, similar to the pigmentation in hair and skin. Like hair, feathers come in many colors, and these colors can be bleached by ultraviolet and light energy in both the sun and in artificial light. Thus the most common damaging agents for feathers are insects and radiant energy.
4Certain feathers also have structural colorants. The protein structure of these feathers, for example hummingbird feathers, are made of a microscopic mosaic of plates of protein surrounded by amorphous protein, that act as prisms for the light (Greenewalt et al,1960). Structural colorants are responsible for iridescence, not only in feathers, but also in materials including butterfly wings and beetle bodies. Because structural colorants are based on the physical form of feathers, damage can occur from mechanical distortions from handling, or from cleaning or adhesive techniques that alter the microscopic physical form. In addition to insects and energy, poor handling and inappropriate treatment can cause damage to feathers.
5A researcher in the 1960’s who confirmed the structural nature of hummingbird feathers observed that they appear dull brown when the iridescence is disrupted or improperly viewed (Greenewalt et al,1960). Many Mexican feather mosaics have brown background passages with tiny traces of iridescent blue-green.
6The conservation treatment of feathers often emphasizes prevention, or the control of insects, light, and inappropriate handling. Treatments may be done for stabilizing broken or bent quills, where adhesives can be safely applied, and reattaching feathers using tying or sewing techniques, and carrying out cautious and conservative cleaning. However the ethic of treating materials reversibly and without visible change makes it difficult to introduce adhesives into the vane of feathers, since this step is often irreversible and disfiguring.
7Feather objects that have had minimal or carefully controlled light exposure will suffer less cumulative fading. With materials such as textile dyes and certain organic pigments, research has indicated which energy bands contained in light cause the most fading damage, and which energy bands are required to permit accurate color rendition for the human eye. This type of research is not well developed for the biological and structural colorants in feathers. One study found Amazonian scarlet macaw tail feathers to be more stable than many blue dyes used as standard comparisons (Solajic et al 2002). Another study of color change of tropical bird feathers found that, with intense lighting, the feathers experienced a rapid color change, and then faded much more slowly (Horie 1990). Different color feathers from the same bird faded at different rates (Horie 1990). With this kind of specific information about damaging energy, lighting engineers have been able to design artificial sources that provide energy only in the bands needed for color rendition, specifically eliminating damaging energy. An important contribution to any exhibit of feather work would be research to determine the safest sources for illuminating these delicate constructions, while still permitting visibility of the prismatic color and texture of feather creations.
8I was privileged to be able to briefly examine the bishop’s miter at the Hispanic Society of America, an extraordinarily beautiful and complex feather mosaic. This opportunity convinced me of the need for a systematic technical study of a group of related objects, for example a group of related miters and infulae held in various collections. Such a study could be designed to identify physical evidence that supports or refutes observations recorded by Sahagun and others. Some technical features that would benefit from such a comparative study include an evaluation of the degree of uniformity in the selection and preparation of amate as a support, and the presence of underdrawing and how it was applied. Since carbon based inks can be identified through infrared imaging, this may be a portable, non-destructive examination method that can be applied. The use of motifs assembled into appliqués that are attached to individual backings, and the order of application of appliqués to the larger backing, might possibly be imaged using low power Xradiography. Finally, an examination of patterns in which highly colored feathers were concealed by other feathers may suggest the significance of certain feathers within motifs.
9A comparative study that promotes our understanding of the amanteca’s techniques, and more research into feathers fading behavior, are two topics that other delegates will inform us about during this seminar. I conclude by listing below the research topics identified by respondents of the feather survey as needing further research.
10How in general should feathers be cared for and conserved?
11How can feathers be illuminated to see the iridescence but not be damaging?
12Have feather mosaics faded completely due to past exposure, or will fading continue? Are we looking at original feather colors?
13Can we better preserve feathers by controlling humidity, photo-oxidation, oxidation, hydrolysis, pH?
14What is the optimum storage and display support for better handling?
15What is the safest fumigation method for feathers?
16Can we determine the causes of deterioration of the adhesive [in feather mosaics] in order to prevent loss of feathers?
17More materials analysis and research into the techniques of manufacture
Solajic, M.R.; Pretzel, Boris; Cooper, M.; Townsend, J.H.; Seddon, T.; Ruppel, J.; Ostapkowicz, J.; Parker, T., A collaborative examination of the colourfastness of Amazonian featherwork: assessing the effects of exposure to light and laser radiation, in ICOM Committee for Conservation,13th Triennial Meeting, Preprints (Rio de Janeiro, 22-27 September 2002), London: ICOM-CC; James & James, 2002 Pp.710-707.