Modern imitation or "paper vellum" is made from plasticized cotton. Usually translucent, paper vellum is often used in applications where tracing is required, such as architectural plans. Like natural vellum, the synthetic is more dimensionally stable than a linen or paper sheet, which is frequently critical in the development of large scaled drawings and plans such as Blueprints. It was also extremely important in that reproduction technology for dissemination of the plans as like a high quality natural vellum, it could be produced in a thin enough sheet to be virtually transparent to strong light enabling a source drawing to be used directly in the reproduction of field-used drawings.
During the last century, antedating integrated CAD and modern laser printing which only came about after development of VLSI based microprocessors, synthetic vellums were at the heart of any large engineering or architectural project. "Blueprints" are a copy of such master drawings, and are used as the field and day to day references originally drafted on the vellum masters. Large paper drawings require an additional step (tracing paper amenable to letting light pass through it, and hence is more error prone). Drafting vellums eventually came to be standardized into a series of drawing sizes known as "A-size," "B-size,"… , "G-size" drawings which doubled in sheet size area with every step. Indeed, VLSI microcircuits themselves were laid out on such vellums layer by layer, "masked" to the dimensions of the given layer (a tracing step of sorts), and those masks photographed, all to scale in very large specialty light boxes. The negatives (known as photomicrographs, photo+micro+graph) thus obtained, were then step-reproduced in carefully aligned arrays and etched onto a glass plate Master of that layer.
In short huge dimensional drawings representing the guts of an integrated circuit were scaled down optically and reproduced to produce each layer of the computer chips which eventually came to be part of the systems which replaced the vellums that made the CAD technology possible. Large scale hand drafted drawings in today's world are unusual and rare, but the old technology still exists and is the foundation upon which the modern computerized world is built. It is still common for engineers and architects to work out the details of a concept, so called "Sketches" on paper drawings before going to CAD. Even in the heyday of hand drafted blueprint technology technical workers found that working with a sketch was an aid to clear thinking.
Vellum is typically stored in a stable environment with constant temperature and 30 percent (+/- five percent) relative humidity. If vellum is stored in an environment with less than 11 percent relative humidity, it becomes fragile, brittle, and susceptible to mechanical stresses; if it is stored in an environment with greater than 40 percent relative humidity, it becomes vulnerable to gelation and to mold or fungus growth.4
- Illuminated manuscript
- ↑ Online Etymological Dictionary Retrieved July 18, 2008.
- ↑ BBC report on Parliament's continued use of vellum, BBC, Tuesday, November 2, 1999. Retrieved July 18, 2008.
- ↑ Frequently Asked Questions about the Houses of the Oireachtas - Tithe an Oireachtais Retrieved July 18, 2008.
- ↑ Eric F. Hansen and Steve N. Lee, “The Effects of Relative Humidity on Some Physical Properties of Modern Vellum: Implications for the Optimum Relative Humidity for the Display and Storage of Parchment,” The Book and Paper Group Annual (1991).
- Alston, R. C., and Brad Sabin Hill. Books Printed on Vellum in the Collections of the British Library. London: British Library, 1996. ISBN 9780712304337
- American Institute for Conservation of Historic and Artistic Works. The Book and Paper Group Annual. Washington, D.C.: Book and Paper Group, American Institute for Conservation of Historic and Artistic Works, 1983.
- Byron, Catherine. The Getting of Vellum. Salmon poetry. Cliffs of Moher, Co. Clare: Salmon Pub, 2000. ISBN 1903392098
- Donovan, Matt. Vellum. Boston: Houghton Mifflin, 2007. ISBN 9780618822126
- Gehring, Stephanie, Ezra Feldman, Ezra Feldman, Stephanie Gehring, and Theo Hummer. Vellum. Ithaca, NY: Soon Productions, 2007.
- Hegedüs, Celia. Paintings on Vellum. London: Offer Waterman & Co, 2001.
- Mowery, Frank. Vellum Repair Techniques Using Japanese Paper. S.l.: Guild of Book Workers, 2006.
- Verheyen, Peter D. Vellum Binding. New York, N.Y.: Guild of Book Workers, 2003.
All links retrieved January 19, 2016.