The effects on parchment to both dry and moist heat are important features to consider. These issues need to be considered when undertaking treatments involving moisture and when choosing environmental conditions for storage and display. If the media is unable to respond to extreme stress it will begin to crack and eventually flake off the parchment surface. The expansion and contraction of the parchment support usually occurs at a faster rate, thus putting stress on the media. (See Housing, Storage and Display and Considerations in Mending Parchment.) Media found on parchment are often affected by the reactivity of the support to changes in relative humidity, especially in cases where the paint or ink may be brittle and/ or thickly applied. (See Potential Alteration/Damage to Object in Treatment.) Methods used for the housing and display of parchment artifacts must also include consideration of its hygroscopic nature. ![]() Treatment goals can often be affected by the extreme reactivity of parchment to changes in relative humidity, particularly when treatments involving the use of moisture are being considered. This often leads to distortion or cockling of the sheet and other dimensional changes which can range from minor to severe, depending on the surrounding environmental conditions. The extremely hygroscopic nature of parchment makes it dimensionally unstable, causing it to expand and contract in response to changes in the surrounding environment. ![]() Parchment is not as prone to acid degradation as is paper, due in part to alkaline agents such as lime and chalk that are used in the manufacturing process. Parchment is susceptible to biological attack and, in extreme circumstances, the collagen structure can be completely degraded in the presence of mold. (Modern parchments made from the inner splits of sheepskins have little tear strength, however, because they lack the tightly connected fiber structure of the grain layer.) Parchment is more resistant than paper to corrosive inks and paints, yet perforation of the support can ultimately occur in the presence of moisture. Parchment is usually a very strong and durable material that is quite resistant to mechanical damage such as surface abrasion, creasing and tearing. and abroad, it has therefore been adopted for use here except where quotations use vellum. Since parchment is presently the term preferred by a large number of conservators, scientists, and scholars working both in the U.S. However, the two words were often used interchangeably, and even sometimes in combination with each other, without any clear distinction between animal type or method of preparation. Vellum was often used to indicate a very fine quality of parchment which was preferred for painting and illumination, or specifically referring to parchment made of calfskin. This material is also referred to as vellum, from the French word vellin derived from vel for veal ("vellum, n." 2022) (alternatively, from the Latin word vitulus and the French word veau for calf (Reed?)). The English word parchment comes from the French word parchemin ("parchment, n." 2022) which ultimately derives from the name of Pergamon, a city in modern day Türkiye and a center for parchment production in the ancient world ("Pergamon" 2022). Parchment is typically described as a highly stressed sheet material with a stiff handle which is made from the skins of small domesticated animals such as calves, sheep, and goats that are cleaned of their hair and flesh and then dried under tension on a frame.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |