Parchment is a writing material made from specially prepared untanned skins of animals—primarily sheep, calves, and goats. It has been used as a writing medium for over two millennium.
In this post, Pritish Kumar gives you an illustration about Parchment paper making procedure – from ancient till now.
parchment, the processed skins of certain animals—chiefly sheep, goats, and calves—that have been prepared for the purpose of writing on them. The name apparently derives from the ancient Greek city of Pergamum (modern Bergama, Turkey), where parchment is said to have been invented in the 2nd century BC.
Parchment made from the more delicate skins of calf or kid or from stillborn or newly born calf or lamb came to be called vellum. A term that was broadened in its usage to include any especially fine parchment. The vellum of most early manuscripts, through the 6th century AD, is of good quality. After this, as demand increased, a great amount of inferior material came on the market. But by the 12th century, when large numbers of manuscripts were being produced in western Europe, a soft, pliant vellum was in vogue.
Making and Processing
- Skinning, soaking, and dehairing
After being flayed, the skin is soaked in water for about a day. This removes blood and grime from the skin and prepares it for a dehairing liquor. The dehairing liquor was originally made of rotted, or fermented, vegetable matter, like beer or other liquors. But by the Middle Ages an unhairing bath included lime. Today, the lime solution is occasionally sharpened by the use of sodium sulphide. The liquor bath would have been in wooden or stone vats and the hides stirred with a long wooden pole to avoid human contact with the alkaline solution. Sometimes the skins would stay in the unhairing bath for eight or more days. Depending how concentrated and how warm the solution was kept. Unhairing could take up to twice as long in winter. The vat was stirred two or three times a day to ensure the solution’s deep and uniform penetration. Replacing the lime water bath also sped the process up. If the skins were soaked in the liquor too long, they would be weakened and not able to stand the stretching required for parchment.
After soaking in water to make the skins workable, the skins were placed on a stretching frame. A simple frame with nails would work well in stretching the pelts. Both sides would be left open to the air so they could be scraped with a sharp, semi-lunar knife to remove the last of the hair and get the skin to the right thickness. The skins, which were made almost entirely of collagen, would form a natural glue while drying and once taken off the frame they would keep their form. The stretching aligned the fibres to be more nearly parallel to the surface.
In modern usage, the terms parchment and vellum may be applied to a type of paper of high quality made chiefly from wood pulp and rags and frequently having a special finish.
Now a days parchment paper, popularly known as vegetable parchment, is a cellulose-based composite that has been processed to give it additional properties like non-stickiness, grease resistance, and resistance to humidity. It is commonly used in baking as a disposable non-stick, grease resistant surface. It should not be confused with waxed paper. because Wax paper that has been coated in wax.
Making and Processing
- Parchmentization of paper
Vegetable parchment paper is made by running sheets of paper pulp through a bath of sulfuric acid or sometimes zinc chloride. This process partially dissolves or gelatinizes the paper. This treatment forms a sulfurized cross-linked material. Which has high density, stability, heat resistance, grease resistance, water resistance, no loose fibers as well as low surface energy. Thereby imparting good non-stick or release properties. The treated paper has an appearance similar to that of parchment and, because of its strength. It sometimes used in legal documents for which parchment was traditionally used. However, parchment paper is manufactured with acid, and has a low pH, making it inappropriate for archival documents . Where acid-free paper is the better choice.
Through time passes by the use of parchment also changed among people. In ancient time it has been used for legal documents and for writing novels where in modern time it been used for cooking, baking for its non-sticky properties. Parchment paper also has relevant properties for other industries. In the textile tube industry, an outer layer of parchment confers the necessary resistance to abrasion, heat and oil. In other industries, parchment is used as a processing aid due to its release properties. Whether for furniture laminate manufacturing and rubber vulcanization.