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Product Profiles: Vellum, Bristol and Mylar

'An Architect's Table' by Thomas-Germain-Joseph Duvivier

Ask the Expert: "Q: What is “vellum”? Is it just paper? What's the difference between vellum and mylar?"

A: The contemporary term “vellum” refers to high-quality, smooth paper for drafting. Historical vellum was originally the prepared skin of fetal calves (veal and vellum have a common etymology). Modern drafting vellum, no longer an animal product, is a type of paper. Usually 100% rag (all cotton or linen) and acid-free, paper vellum has a smooth, lightly toothed surface for crisp line work in pencil and ink.

Because of its high rag content, paper vellum is able to withstand erasing and burnishing better than wood fiber paper; it's also less prone to release fibers which can clog pens.

Strathmore logo blind embossed on a sheet of vellum bristol

The term "vellum" is also used for one type of Bristol Board, a high quality card stock for drafting and illustration. Vellum Bristol has a slight tooth which makes it good for graphite and colored pencil, while the hard, smooth surface of Plate Bristol is better for ink line work and markers.

Vellum and rag paper were not the only traditional supports for drafting. From the late 19th to mid-20th century, blueprints and technical drawings were also done on Drafting Linen, a support made of heavily sized, calendared (pressed) thin fabric. Drafting cloth was replaced by acetates and synthetic films in the second half of the 20th century, but vintage drafting cloth is still sought after for sail cloth in model ships. Linen-textured stationery still echoes the characteristic surface of this extinct drafting supply.

Drafting Mylar is a man-made polyester film with one or both sides 'frosted' (finely textured) to accept ink, graphite, marker, colored pencil and other media. Mylar permits more vigorous erasing than paper vellum, and even withstands use of light solvents to remove inks. Unlike earlier acetates, polyester films are highly durable with excellent stability in storage, making this material ideal for many archival applications.

Because its surface is impermeable, friable (powdery) drafting media may not adhere well to film. Polymer drawing leads with plastic filler were developed to achieve better adhesion on film than with traditional clay-based leads.

Mylar is also popular for artistic drawing. Transparency, impermeability to wet media and a suave surface make drafting film an attractive option for colored pencil, marker and even water-based paints. It's even possible to change the background color of a drawing on film by simply mounting a different toned sheet or board beneath the artwork.

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