| Why Canvas is not the Best Choice for Painting 
The crack patterns on this painting show a variety of problems typical of stretched textile supports, such as low profile stretcher bars, re-tensioning, loss of mechanical strength, cycles of relative humidity (RH), and shock and vibration.
Although the majority of paintings today are painted on canvas, it is not the best choice for painting—in fact they lead to cracking early in the life of a painting. For over a hundred years, most of the causes of cracking have been explored: humidity and temperature, expansion and contraction, stress, and paint embrittlement. The symptoms were obvious—cracking and paint loss—but the causes were not clearly understood. In 1982, Marion Mecklenburg and other scientists at the Smithsonian Institute, reported the first systematic explanation of painting mechanics, and especially that of canvas paintings, while other researchers at the Canadian Conservation Institute (CCI) soon followed. Canvas is hygroscopic, meaning that it readily absorbs and releases moisture from the environment. As humidity in the air changes, canvas absorbs and releases moisture to maintain equilibrium with these changes. Canvas swells and contracts at much different rates than paint layers, producing mechanical stress on paint as the environment changes. (The environment constantly changes due to changes in temperature and relative humidity.) Although these changes may appear to be small, over time they place much stress on paint, which leads to cracking, cupping and paint loss. 
This canvas shows a “spider” crack pattern usually caused by poking a brittle painting on canvas.
Canvas is a very flexible material that is also biaxial, so it expands and contracts at different rates according to its axes—the weft and warp direction of the yarns. The layers in paintings that carry most of the tension (varnish, paint, ground and size), on the other hand, are composed of amorphous or semi-amorphous polymers that are much less flexible, and expand and contract to a much lesser degree and equally in all directions. These stiffer materials are subjected to much stress as the canvas expands and contract, resulting in cracks and then finally loss of adhesion and cupping (illustrated by the animation). Shock and vibration, low temperature, low humidity, high pigmentation, and aging increase both the stiffness and the likelihood of cracking of these layers. 
Canvas expands and contracts with changes in relative humidity causing cracks and cupping in the paint layer.
Paintings on rigid supports (wood, stone and metal) with lower response to environmental changes, such as relative humidity, are preserved for much longer periods of time, because the support does not induce as much stress on the paint film. Cracks on canvas paintings are predictable and museums conservators can predict the appearance of such cracks through mathematical modeling, such as those appearing in the paintings above, where even changes in crack patterns appear above the location of stretcher bars than over other areas of the canvas. For this reason artists who are concerned about the posterity of their work should choose rigid materials as supports, because this choice will lead to a better outcome for their paintings. This is the topic of the entire first day of the Painting Best Practices workshop and one of amy subjects explored in detail at the three-day workshop. Learn more about the
Painting Best Practices Workshop.
Painting Best Practices Workshop Location and Dates Sadie Valeri Atelier, San Francisco, CA—May 29–31, 2015 Grand Central Atelier, Long Island City, NY—September 11–13, 2015 Rochester Art Club, Rochester, NY—September 15–17, 2015 Articulations, Toronto, Ontario, Canada—September 19–21, 2015 Register here for these workshops or for more information Want this workshop for your local school or atelier? Controlling the Creative Process Workshop Justin Hess Studios, San Francisco, CA—July 11–12, 2015 This is a special two-day version of the Painting Best Practices workshop in conjunction with Justin Hess' five-day materials workshop. For more information and to register for this workshop visit Controlling the Creative Process.
George O'Hanlon and Tatiana Zaytseva prepare to demonstrate paint making at the Gage Academy of Art
About the Painting Best Practices Workshop The information-packed workshop includes all aspects of constructing a painting from the support and ground to the final layers. Practical procedures will be clearly explained and demonstrated on how to build your paintings based on conservation research during the past century. This workshop is designed for painters of all mediums, but special emphasis is given to oil painting. The workshop begins with a review of the leading causes of cracking and paint loss in paintings. In light of the research, we review different types of painting supports to help you choose the best one for your painting technique. We review the most suitable grounds for each type of popular support and painting and review factors influencing the embrittlement of the paint film and what artists can do to prolong its life. Throughout the workshop we provide recommendations involving different supports, grounds and painting techniques that will help you make technically-sound paintings. The workshop covers these areas of painting:
Supports
Stretched canvases
Wood panels
Composite panels
Copper plates
Grounds
Traditional and modern sizes
Chalk and gesso grounds
Oil and alkyd grounds
Acrylic dispersion grounds
Paints and Mediums
How to make oil and tempera paint
Pigments and extenders
Natural and synthetic resins
Waxes, gums and oils
Solvents and diluents
Driers and drying oils
Varnishes
Natural and synthetic resin varnishes
Temporary vanishes
How to apply varnishes
Brushes
Natural and synthetic hairs
How to identify good quality in brushes
Brush types and their uses in painting
Pigments
Types, nomenclature
Lightfastness, compatibility and permanence—are they the same?
Artists’ materials—how to read the labels Read the complete curriculum
What Attendees Say about the Workshop Read Matthew Innis's extensive review of this workshop in Underpaintings. This is an online magazine that is worth the annual subscription. Natural Pigments endorses Underpaintings magazine as one of the top online resources about painting and visual art. Absolutely necessary and excellently delivered—Painting Best Practices is a workshop that addressed questions I have had about my practice for years and, due to Mr. O’Hanlon’s clear and genuine love for art and concern with its best possible development and preservation, the information was faultlessly structured and extremely well delivered. I have filled a whole book with copious notes.
—Jo Fraser, London Thank you for an excellent workshop. Your knowledge is truly impressive. I feel I have a good foundation of knowledge now to begin changing my methods and materials. Also, I will talk to the GCA and see if we can have you bring the workshop to our students!
—Joshua La Rock, instructor, Grand Central Academy, New York
(Note: The Grand Central Academy was so enthusiastic about the workshop they engaged the instructor to teach it to all their students.) I took this workshop last fall and found it so rich in information that I want to offer it to my students.
—Koo Schadler, Alstead, New Hampshire Thanks for all the excellent information—that was a tremendous workshop!
—Louie Lane, artist assistant to Cecily Brown, New York Just wanted to send you my little blog post about our weekend at the Painting Best Practices workshop. Doug and I had a wonderful time, and truly appreciate the depth and quality of your workshop.
—Jody Mattison, Antioch, California
Read the review by artist-instructor Jody Mattison on her blog. Great workshop. What Pat and I came away with was the feeling that what we learned would have taken years. But you did it for us in a weekend! Really appreciate your “obsession” and what you have learned and conveyed to us. I am serious—write a book!
—Jerzy Niedojadlo, Nitram Fine Art Charcoal I enjoyed your workshop very much and reported on it enthusiastically to my teachers at the Academy of Realist Art, Boston.
—David Valbracht, Boston 
Tony Curanaj (far left) and Edward Minoff (near left) interview George O'Hanlon, as Tatiana Zaytseva (center), cofounder of Natural Pigments, keeps close tabs on the Podcast production.
The latest Suggested Donation podcast features a geek-out on artist's materials with George O'Hanlon, technical director and founder of Natural Pigments. The podcast was recorded at the Grand Central Academy of Art on the heels of his workshop on painting best practices. Jay Braun brings his audio engineering pyrotechnics to the table.  Listen to the Podcast
Where the Workshop Has Been Taught Natural Pigments has taught hundreds of artists technical information regarding artists’ materials and painting techniques during the past year at these workshop locations: Townsend Atelier, Chattanooga, Tennessee
April 24–26, 2015 Studio Incamminati, Philadelphia, Pennsylvania
April 10–12, 2015 Ani Art Academy Waichulis, Bear Creek Village, Pennsylvania
April 7–8, 2015 Cloud Castle Art Studio, Saratoga, California
January 23–25, 2015 Eastside Artists Collaborative, Bellevue, Washington
November 7–9, 2014 Gage Academy of Art, Seattle, Washington
November 4–6, 2014 Electric Zoo, Saint Petersburg, Florida
October 3–5, 2014 Kadmium Art + Design, Sydney, New South Wales, Australia
September 12–14, 2014 Natural Pigments, Willits, California
August 15–17, 2014 Vicki Walsh Studio, San Diego, California
June 21–23, 2014 Koo Schadler Studio, Alstead, New Hampshire
June 8–9, 2014 Grand Central Academy of Art, New York, New York
April 3–4, 2014 Grand Central Academy of Art, New York, New York
April 1–2, 2014 Grand Central Academy of Art, New York, New York
March 28–30, 2014 Accent Arts, Palo Alto, California
March 15–16, 2014 Center for Academic Study and Naturalist Painting, Springville, Utah
March 6–8, 2014 Oregon Society of Artists, Portland, Oregon
February 28–March 2, 2014 Peggy Nichols Studio, Los Angeles, California
October 12–13, 2013 Articulations, Toronto, Ontario, Canada
September 28–29, 2013 DoubleTree Hotel, Fort Lee, New Jersey
September 21–22, 2013 Natural Pigments, Willits, California
August 24–25, 2013 Need more information?
Want this Workshop for Your School or Atelier? If you or your school would like to schedule a workshop in your local area, please call 1-888-361-5900 or reply to this email to learn more about how this can be arranged. We are already scheduling workshops at private schools and ateliers at locations in the U.S. for 2015 and Europe for Fall 2016. |
