This past autumn, I had the privilege of attending a two-day workshop in northern New Jersey (within sight of the George Washington Bridge in the now infamous town of Fort Lee no less) which dealt with the subject of longevity in paintings. Titled, "Painting Best Practices," the class was taught by artist materials expert George O'Hanlon, and it was one of several he offered on the topic at different venues throughout North America near the end of 2013.
George O'Hanlon |
O'Hanlon, for those unfamiliar with him, is an accomplished gentleman who has worked tirelessly on behalf of the arts. He is the Executive Director of Iconofile, an in-depth, online database of traditional Christian iconography which catalogs not only the images in these paintings, sculptures, and pieces of fiber art, but also their histories and the techniques behind making them; a contributing member of AMIEN, the Art Materials Information and Education Network, which was founded by the late Mark David Gottsegen, an internationally-esteemed authority on art supplies; and he is also a member of the American Society for Testing and Materials (ASTM), who has, in his capacity on the committee for Artists' Paints and Related Materials, lobbied for such causes as universal paintbrush sizes, and against such ideas as those which call for uniform particle size across all pigments, a move which he considers could be detrimental to the enduring beauty of artists' colors.
For those of you who do know O'Hanlon, he is also, of course, founder and president of the art supply company, Natural Pigments, an achievement which, as odd as it may seem, I intentionally overlooked in the previous paragraph. Why? Because, surprisingly, O'Hanlon's relationship with Natural Pigments had very little to do with this workshop.
What could have easily been a two-day sales presentation - which would not necessarily have been unwelcome to the participants - simply was not. O'Hanlon did not even bring any of his company's products along to sell, and when asked why he had not, the expression on his face indicated that the thought had never crossed his mind. But this honest omission on his part is rather revealing : it shows the integrity of George O'Hanlon and his wife Tatiana Zaytseva. They hosted this workshop to teach painters how best to increase the longevity of their paintings, not to promote themselves. This is not to say that Natural Pigments' products were never discussed; the goal of Natural Pigments is to make the best available materials possible, and of course O'Hanlon knows his own product line well, so Natural Pigments' items were certainly mentioned. But if a competitor makes a good product, O'Hanlon will not hesitate to say so; he never disparages another company, and he regularly recommends other people's products. He is simply less concerned that artists buy his products, than he is that they buy the right products.
George O'Hanlon just honestly loves art, and he wants all artists to be able to make the best paintings they possibly can.
From the moment O'Hanlon began his presentation, I was taking notes. By the end of the first sentence, however, I already felt I had fallen behind; there was nothing extraneous in his delivery, and no down time between interesting topics to allow me to catch up with my record. Everything he imparted was informative and useful. Of course, it helped that O'Hanlon had geared this particular presentation toward oil painters, as most of us there worked in that medium; perhaps if he had been speaking more about a medium other than my preferred one, I may have found some moments to let my pen rest, but I doubt it.
Tatiana Zaytseva demonstrating the different ratios of linseed oil to pigment relative to color. |
With so much information to offer, the question has of course arisen, "Why doesn't O'Hanlon write a book, or make a set of DVDs on the topic, rather than do these workshops?" It is not that O'Hanlon is adverse to the idea, but he realizes that there is a limitation to either of those pathways, namely that the pace at which new discoveries are made in the fields of paint durability and conservation, far outstrips the speed at which proper books or DVDs on the topics can be produced. (This was a problem that O'Hanlon witnessed with his friend, Mark Gottsegen, who wanted to annually update his excellent reference guide, The Painter's Handbook, but who was met with resistance by the publisher, who, justifiably, could not put out revised editions so often).
It is for these reasons that I highly recommend O'Hanlon's workshops, and if you have the opportunity to attend one, I encourage you to do so. I warn you that it may at times get heady, but if you are someone like me – and it is likely you are – who puts a lot of time in your work, and hopes that it will last for generations, this is information that could be of the utmost importance to the success and satisfaction you gain during your career as an artist.
O'Hanlon has six Best Practices workshops scheduled for this winter. The first is in Portland, Oregon later this month, with three taking place in March – in Springville, Utah; Palo Alto, California; and New York, New York; and two in June; in Alstead, New Hampshire and San Diego, California. Most of these have been extended to three day events, which is ideal, but you really cannot go wrong either way.
I do hope that George and Tatiana bring some of their Natural Pigments product line with them for this round of workshops, however, as having the opportunity to see the quality of their paints and other supplies in person is the best convincing you could ever have to try them out. Currently, Natural Pigments is only available for purchase through the company itself, or through a few hand-picked outlets throughout North America. Natural Pigments has been approached by larger retailers seeking to carry their goods, but George and Tatiana have so far preferred to keep their items in arenas where the sellers have product-specific knowledge and are more available to answer consumer questions directly. And yes, this means on top of everything else George does, he makes himself as available as possible to personally answer customer questions via the telephone or through email if you are buying from him.
Yes, he really is that kind of business owner, and yes, Natural Pigments really is that kind of company.
For more information on the upcoming Painting Best Practices workshops, including locations, tuition, and registration, please consult the following links:
More information can also be gained by calling Natural Pigments at 1.888.361.5900.
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I have decided, with O'Hanlon's blessing, to post some of notes from the workshop here on the blog. Not all of my notes will be included, however, and I plan to focus only on the first day of the workshop in this present post (I may include notes from the second day in a future post if there is enough interest). Even so, what I will include below does not represent all of my notes from that initial day, as there are several items I came across while reviewing my records, of which I can now make neither heads nor tails (I certainly could benefit from enrolling in the workshop a second time!). I imagine that many of these same topics will be covered in-depth again during the upcoming seminars, but even were all of my notes from both days reproduced here, I am certain that it would not represent the entirety of O'Hanlon's program. In addition to whatever I have missed, O'Hanlon will no doubt include any new discoveries made since last September in his upcoming presentations, and it is likely that he will be able to include more information in general during his longer, three-day workshops. Plus, it must also be taken into account that the workshops are participant-driven, with O'Hanlon answering questions from previously submitted emails, and on the spot. (During the two-day workshop I attended, O'Hanlon was only derailed by one question, which had to do with the possibility of wax migration from a protective, finishing layer, down through paint layers to the ground; though O'Hanlon stated that wax added to paint as an extender will freely migrate through all paint layers, he was unable to commit to the certainty of wax from a sealing coat penetrating all the way to the support. It was something he wanted to research more before answering).
- Painters are the only artists who don't work with raw materials (egg tempera is the exception)
- Three types of painting failures are : Mechanical, Chemical, and Biological (mold, fungi, insects, etc.)
- Paintings are a composite system - the paint affects the support, and vice versa.
- Paint films act differently depending on the support - Flexible vs. Rigid.
- Like building a house - the structure may be sound, but if the foundation is weak, it can still collapse.
- Different colors expand and contract at different rates. This can lead to cracking in the paint film.
- Blisters are the result of poor adhesion or the loss of elasticity.
- The paint layer actually supports the canvas!
- Rigid supports prevent many problems.
- A sound support copes with handling and transport; has a low response to Relative Humidity and temperature; is chemically stable; and is visually acceptable.
- Solid Wood Supports are extremely hygroscopic; their mechanical response to temperature and humidity is orthotropic.
- Hygroscopic - the ability to attract and hold water
- Orthotropic - responds in different directions. In the case of wood, in changes according to where it was cut: radial, longitudinal, and tangential.
- Wood supports have little longitudinal change respective of Relative Humidity or temperature, and only slightly more change in terms of radial movement. Tangential movement, however, is significant in correlation to changes in humidity or temperature.
- Paint should move in the same way as the support.
- Over time, wood deforms; cells wear out.
- Wood panels should be air-dried for many years.
- In the Renaissance, panels were chosen with the understanding that they would warp outward (in the direction of the wood rings).
- Joined panels which formed an undulating S-curve were better (in an alternating fashion, convex and concave panels joined together to form a support that had a "wavy" surface. The tension of the panels curving in opposite directions kept the support relatively "flat").
- Plywood is made of an odd number of wood layers, with each layer placed at a right angle (relative to wood grain) to the previous layer.
- Plywood Pros: excellent strength, stiffness, and resistance to creep; less dense than fiberboard; birch plywood has excellent hardness
- Plywood cons: anisotropic (directionally dependent, i.e. it is easier to split with the grain than against it); contains urea-formaldehyde resins; absorbant; veneer prone to "checking" (thin, long, and relatively straight cracks in the paint film usually in the direction of the grain)
- Fiberboard (high density and medium density bound with a synthetic glue) Pros: isotropic (uniform in all direction, i.e. no grain); deforms less than solid wood in high humidity; excellent strength and hardness.
- Fiberboard Cons: contains urea-formaldehyde resins; denser than plywood; subject to physical damage; fibers raise when wetted.
- Hardboard (Masonite®) - steam pressed and bound with lignin, a natural glue polymer - is rare
- Hardboard Pros: isotropic, deforms less than solid wood in high humidity; excellent strength and hardness.
- Hardboard Cons: denser than plywood; subject to physical damage; fibers raise when wetted (but less so than fiber board).
- Tempered Hardboard (oil coated) is less hydroscopic.
- Tempered Hardboard was formerly made using linseed oil. Now soybean oil is used.
- Panel Grades: (A) no surface knots; (B) knots have been filled in; (C) open knots
- Flat Cradling (used for bracing wood panels) is the oldest form of cradling
- Flat Cradling systems from the second half of the 18th c. consist of glued vertical strips of wood, and sliding horizontal strips (if both directions were glued, the cradling could damage the panels when it reacted to humidity and temperature differently than the panel)
- Raised Cradling (19th c.) had deeper recesses and required less gluing.
- Button Cradling consists of many small pieces of wood glued to the back of the panel with slots allowing for sliding horizontal strips.
- The less that is glued to the back of panel when cradling, the better.
- A painting is a system - once something is added (canvas, paint, cradle, etc.), it acts as part of that system.
- Attributes of the Ideal Adhesive: minimum negative aging characteristics (it doesn't yellow, become brittle, etc.); sets without generating stresses; resistant to climatic influences (not hydroscopic); resistant to microorganisms; possible to use cold; is no more rigid than the panel (it must have some flexibility).
- Types of Adhesives: glutoline and collagen glues (hide glue); casein glues; artificial resin adhesives
- Rabbitskin Glue in the USA is made from pork and beef (by-products of the meat industry). Its name refers to strength only, not its source material.
- Isinglass glue is made from the dried bladders of Russian sturgeon - it is used by conservators to correct delamination.
- Fish glue has good strength and remains liquid at room temperature.
- Collagen glue is made from animal bones, cartilage, and hooves (and less frequently, animal hides).
- In the USA, glue has a deodorizing agent added; European glue smells like road kill.
- Casein glue is a skim milk derivative. It is good at filling pores and it is less hydroscopic than collagen glues. Casein glue hydrolyzed with lime is best version.
- PVA glue (polyvinyl acetate) is a better glue, though under certain circumstances it can release acetic acid.
- Lineco makes a good PVA glue.
- Talas Aquazol (another brand of adhesive) is hydroscopic.
- Acrylic gels when used as adhesives suffer from not being easily reversible during conservation.
- Protective Backings are important!
- Earliest form of protective backing was to paint on both sides of a panel.
- Moisture can't go through pigment!
- Backings slow down the moisture cycle.
- Direct Backing Types: pigmented shellac, fused beeswax, fused beeswax and shellac, metal and plastic foils.
- Indirect Backing Types: plywood boards, fiberboards, composites.
- Gesso does not make for a good direct backing - it is hydroscopic.
- Polyurethane might not make for a good direct backing.
- Zinsser makes a pigmented shellac.
- Plastic Supports - Pros: rigid, lightweight, low moisture absorption
- Plastic Supports - Cons: low to moderate thermal expansion (paint and panel should move the same), susceptible to UV damage.
- ABS (Acrylonitrile Butadiene Styrene) plastic is pretty good.
- Sintra® PVC - closed cell polyvinyl chloride foam board.
- Plastics have low-energy surfaces, i.e. it is hard to adhere to them.
- Aluminum Composite Material (ACM) or Aluminum Composite Panels (ACP) are the standard names for the material most artists refer to as Dibond®
- ACM Pros - excellent strength; lightweight; easy to fabricate; not hydroscopic; expands and contracts at nearly the same rate as paint.
- ACM Cons - expensive; not as readily available as other materials.
- ACM can be cut with a plexiglass blade.
- Paint on the coated side of the ACM. Scuff it first, then wipe it clean with isopropyl alcohol. Do not sand down to the aluminum.
- Beva® makes an adhesive available in sheet form (#371), which can be used to fasten canvas or linen to an ACM panel. It dissolves in toluene.
- Honeycomb aluminum panels are an excellent painting support. They are lightweight, have excellent strength, and do not warp. However, they are difficult to fabricate and very expensive.
- Copper Panel Pros - does not warp, excellent strength, lightweight
- Copper Panel Cons - expensive, difficult to fabricate. Can also suffer from oil-canning (moderate buckling).
- Some of the best preserved paintings were done centuries ago on copper panels.
- Linen vs. Cotton - Linen: 2-3 times stronger than cotton; absorbs more moisture and dries quickly; relatively more expensive; Cotton: weaker than linen; absorbs moisture and dries quickly; low cost; readily available.
- 19th c. linen was stronger than today's linen. It had longer fibers.
- Looser weave linen (non-mechanically woven, perhaps) is better for painting.
- Artificial textiles have high strength and stiffness and a low moisture response.
- 9.1 oz Clipper and Fredrix® Polyflax 1008 are good polyester fabrics for artist use.
- O'Hanlon doesn't recommend flexible supports at all.
- The stretcher key was introduced in the mid 18th c..
- Sapwood stretchers are too absorbent.
- Cross members should be introduced one for every 30" of stretcher length. They should be made of a different wood from the stretcher bars.
- Low lips on stretchers create a microclimate between the bars and the canvas back, which can lead to problems.
- John Annesley Company in California makes expansion bolt stretchers for precise tension control.
- Switching from stretched canvas to a rigid panel will remove 90% of future problems.
- On a macro level, there is little difference between staples and canvas tacks.
- A tack has the same surface area under the head as a staple area.
- When attaching canvas to the stretcher bars, place a strip of mylar between the staple and the canvas. This increases the surface area affected by the staple, and makes removing the staples at a later date easier. Make sure to use low-profile staples.
- Copper coated tacks are good for attaching canvas to the stretcher.
- Staple the canvas on the back of the stretchers. This broadens the stress point placed on the canvas across the edges.
- Place staples parallel to the edge, 1" to 1½ " apart at most. More staples distribute the stress on the canvas.
- Fold the fabric at the stretcher corners using "hospital corners" - this reduces the point of stress.
- It's good to have a humidity and temperature gauge in your studio.
- The optimum temperature for stretching a canvas is between 64 - 74˚.
- Stretch your canvas in a moderate environment. Calculate your margins, align the stretcher to the weave, draw weave lines, line up and set corners, and STRETCH FROM THE CORNERS using pliers.
- Conservators now feel that stretching canvases beginning in the corners and moving toward the center of each side is better than starting in the middle and moving out toward the corners.
- Variations in canvas tension can lead to cracking in the sizing, ground, paint, and varnish layers. Uneven stresses placed at the corners create radiating cracks, commonly seen in 19th c. paintings.
- When stretching a canvas, set the sides with push pins along the edge first, before tacking or stapling on the back. Tension is then placed over a short distance - from the push pin to the staple or tack.
- Pre-stretching an unprimed canvas (setting the fibers in place) - Stretch by hand; wet with a fine mist first; then wet thoroughly; let it dry completely.
- Never leave your paintings in a hot car!
- A backing for a stretched canvas acts as buffer from environmental changes, protects against mechanical damage, and keeps out dirt and debris.
- A good backing can be made from hardboard. Attach hardboard to stretcher backs using screws and washers. Make sure the screw holes in the hardboard are large enough to accommodate movement in the hardboard (expansion and contraction) created by environmental changes.
- A backing with holes in it (some people erroneously believe this allows the canvas to "breathe") creates its own environmental climate, different from that affecting the rest of the painting.
- There is nothing permanent in art materials! We can use "longevity" and "durability" when discussing art materials, but not "archival."
- We should all paint frescoes! They are the most durable paintings.
- Have a healthy distrust for commercial art products. They are marketed to hobbyists, so longevity is not the issue, price is.
- Most canvases must be relined after 100 years.
- Light and oxidation are the greatest threats to all painting materials.
- 15th c. paintings are in better condition than 17th c. paintings, which are, in turn, in better condition than 19th c. paintings.
- Types of sizing: animal collagen glue, PVA, or acrylic dispersion.
- Size is considered part of the ground. On stretched canvas, it is used to stiffen the fabric, and not necessarily for creating a barrier between the support and the paint. On wood panels, size provides a barrier and creates a uniform painting surface. Size is unnecessary on metal or plastic.
- Grounds act as a barrier between the support and the paint layer, provide a receptive surface for the paint, and present a suitable background for the paint.
- Types of grounds include traditional gesso or chalk; oil or alkyd; and acrylic dispersion (e.g. what many companies confusingly call "acrylic gesso")
- Gesso is the Italian word for gypsum (calcium sulfate). Whether you used the word "gesso" or the word "gypsum" depended on which side of the Alps you were from.
- Up until the late Renaissance, gesso (calcium sulfate) was primarily used for grounds in Italy, while Northern Europe used chalk (calcium carbonate).
- In making gesso (gypsum + animal collagen glue), the glue quantity should be low, without under-binding. Ideally, gesso should be 81.6% calcium sulfate by volume in relation to the glue.
- To cut the porosity of a chalk ground, coat it with oil or shellac.
- Lead oil grounds suffer little free-swelling strain.
- Hide glue has great stiffness, but weakens at high humidity.
- Contrary to common belief, acrylic does respond to moisture.
- The "yield point" is the specific point after which a stretched material can no longer return to its original state. (stress/strain)
- The yield point of paints is lower than the flex rate of canvas.
- Zinc white is very rigid, but breaks quickly.
- The breaking point of paint occurs when elongation can no longer occur under applied stress, and the material separates.
- Titanium white is less rigid, but also has a poor breaking point.
- According to the Proposition 65 Awareness Act in California, titanium dioxide (when airborne) is a possible carcinogen.
- In food, titanium dioxide is basically inert.
- Oil paint on an acrylic ground has good adhesion, and is very stable.
- Acrylic grounds improve the flexibility of oil paint, especially alkyds.
- Adhesion - when 2 things cling together.
- Cohesion - when one thing clings to itself.
- Mechanisms of adhesion: mechanical, chemical (weak form of bonding), dispersive (Van der Waals forces), electrostatic, diffusive.
- Metal surfaces have micro fissures (mechanical adhesion)
- Acrylics cure over a longer period of time than previously thought.
- Acrylic-primed canvas is better than today's oil-primed canvas, only because lead paint is no longer used (unless specified). Titanium and zinc used in grounds are far too brittle.
- The art market is reliant on all other industries. "We're the step-child."