one of the oldest and most durable media

Casein: Its Use and Characteristics

by Cathy Bennett

The following article was contributed by Jack Richeson & Co., a Wisconsin based company that manufactures artist supplies:

Casein (kay’seen) is a quick-drying, aqueous medium using a milk-based binding agent. It is one of the oldest and most durable media known to man, even pre-dating its cousin - egg tempera. Nine thousand year old casein cave paintings have been discovered in Asia, and the medium was used by the ancient Egyptians for brightly colored murals called fresco secco. In the 12th century, Theophilus Presbyter, a German monk who documented medieval arts and crafts, first described the preparation and use of casein. In the 14th and 15th centuries, Renaissance artists, including the Old Masters, adapted Presbyter’s recipe and used casein both for finished paintings and underpaintings. In more modern times, Edvard Munch used casein in his most famous mixed media work, The Scream. Gustav Klimpt painted his renowned six-panel Beethoven Frieze with casein and decorated it with gold and semi-precious stones. Other noted artists as diverse as Thomas Hart Benton, John Sloan, Ben Stahl, Hans Hoffman, Ben Shahn and Stuart Davis also used casein. In 1933, casein pigments in tubes were developed by the Spanish American painter Ramon Shiva, who relied on the expertise of well-known Chicago artists and illustrators to help perfect his high-quality paints. During the 40’s and 50’s, Shiva was the leading oil paint manufacturer in the United States and led the world in reviving interest in casein, which was widely used until the 1960’s when acrylics began to dominate the market.
Known for their versatility and capabilities, casein paints share many characteristics with other media, making it possible to create a wide variety of effects using many different techniques and surfaces. Casein paints may be used to create the thin washes of watercolor, the smooth opacity associated with tempera and gouache, or to create the richer textures of oil and acrylics. They can be reworked or layered repeatedly and they are also ideal for underpainting. Unlike oils, casein is a clean, water-soluble medium requiring no strong solvents. Its quick-drying properties also make it possible to glaze within a few hours and move onto the next stage instead of waiting for days for the paint to dry. Layering is also much easier than with gouache or watercolor, and unlike watercolors, casein paints are correctable. Casein may be applied to any rigid non-oily surface such as canvas panel, illustration board, heavy watercolor paper, claybord, plaster, metal, wood, Masonite, or canvas or linen mounted on Masonite. Unless an artist is very familiar with casein, the medium is not generally recommended for stretched canvas because if it’s applied too thickly or in an impasto style, it will crack. Almost any kind of brush can be used with casein depending on the effect an artist wants to create - everything from stiff white bristle brushes to soft hair watercolor brushes, oil brushes, calligraphy brushes and fine points for tempera style. Because casein dries so quickly, it can be hard on brushes and most artists prefer to use synthetic brushes instead of more expensive brushes such as fine sables. Many artists also use rags for toning, toothbrushes for splattering, and sponges for textures. Casein has an exceptional integrity of color and always dries to a perfect velvety matte finish that can be buffed to a satin sheen or varnished to produce a resemblance to oils. Over time, casein pigments become resistant to moisture and may actually be cleaned with a damp cloth.

Artists share their casein expertise
To illustrate just how versatile casein really is, we asked five artists to share their techniques and expertise with us. Four of the five – Robert Tanenbaum, John Molnar, Michael Boss and Stephen Quiller – have been painting in casein for at least 20 years and use the medium in entirely different ways. Our fifth artist Douglas Wiltraut, who is known for his egg tempera and watercolor paintings, agreed to try casein paints for the first time and share his experience with us. We also spoke with Ross Merrill, the Chief on Conservation for the National Gallery of Art in Washington D.C. Merrill, who is also an accomplished plein air artist and contributing editor to the Technical Q & A Section of The Artist’s Magazine. Ross Merrill provided us with a conservator’s insights into casein and offered some important “do’s and don’ts.”

Robert Tanenbaum
Tanenbaum didn’t begin working with casein seriously until the early 70’s when a fellow illustrator who specialized in automobiles showed him how much easier it was to add highlights using casein paint instead of watercolor or gouache. He found casein was perfect for the tight details and textures he was trying to achieve. He also found casein’s quick drying properties made it ideal for the tight deadlines and overnight changes that illustrators inevitably face. When working in oils Tanenbaum continues to use casein for his preliminary color sketches and for underpainting. “Years ago, I learned that by doing small preliminary color sketches I could work out the composition, colors and value patterns. That way I could spot problems early on, so that I could be more spontaneous with my final images, instead of laboring over them. “I think casein is the best choice for color sketches because it usually dries within a few minutes and I can make changes immediately or quickly move onto the next stage.”
When doing colored casein sketches, Tanenbaum uses Crescent #1 Watercolor Board and begins with a fairly detailed drawing of the figure. Then he begins laying in the casein, using the same techniques as he does with oil – painterly brush strokes, and blending and softening the edges before the casein dries entirely. When he gets his color sketch to a level he’s happy with, he’s ready to approach his final oil painting. Again, casein plays a major role. “When I paint in oil, I still tone with casein because I can use oil as soon as the casein feels dry to the touch. If I tone with oil, I have to wait for a long time until it sets up. “Then I lay on an opaque casein passage to completely cover the white of the canvas, but I’m careful not lay it so thickly that it becomes impasto. After that I begin painting with oil.”
Ross Merrill, Chief of Conservation for the National Gallery of Art in Washington D.C. has this to say about underpainting: “As long as an artist doesn’t lay on casein too thickly, it’s an excellent choice for underpainting because it’s insoluble once it dries. The casein will easily accept the oil and will form a good mechanical bond, ” “One thing an artist must never do is underpaint oils with acrylic paint, says Merrill. “Acrylic paints are formulated with a ‘closed’ surface to protect the paint from stains, grime and other pollutants. This ‘closed’ surface is non-absorbent and will not form a good mechanical bond with oil. Over time, the oil on top could actually delaminate and come off in layers. “Using acrylic gesso works fine with casein or oil paint because it has an ‘open’ surface to accept the paint layer and form a mechanical bond.”

John Molnar
John Molnar began painting in casein in art college under the tutelage of James Hill After a short stint as a storyboard artist and illustrator and a growing dissatisfaction with the world of advertising, Molnar turned to painting full time, with casein being his medium of choice. “When I turned seriously to fine art, I also painted with watercolor and acrylics, but I liked the feel and performance of casein better,” explains Molnar. “These days I paint in oil in addition to casein, but I’ve set up my studio so that the most ventilated room is for oils, which is very important, especially during winters in Toronto, where I live and have my studio.”
Molnar used to do his casein paintings on Masonite panels, but now he usually paints on canvas or linen, which he affixes to plywood panels. He makes the panels himself by sanding down the plywood and sealing it with a 50-50 mixture of Weldbond PVA glue and water. Then he pastes the canvas or linen on the panel and overlaps it on the back, making neat folds at the corners. The next day he applies gesso, thin coats of shellac or PVA glue, usually sanding to a smooth surface because that’s what he prefers to paint on. “I find the weave in canvas or linen produces a more interesting effect than Masonite,” explains Molnar, “and that I can use the warp and weft to create beautiful tonal gradations by simply dragging my brush over the surface. “I’ve also been experimenting with unprimed acrylic cloth (polyester) which I sand a bit to make the paint adhere. The more fluid casein sinks into the fabric, while casein applied with a dry brush technique sticks to the surface. What you end up with are diffused ‘washy’ layers charged up with crisp highlights. It really stretches the casein look and produces a strong resemblance to oils.” “Recently I’ve been using casein more like oil than tempera,” Molnar points out, “but for both styles I paint thin, building up my paintings with layers and glazes. “For extra translucent glazes, I thin the color I want to use with Shiva Casein Emulsion. Although I don’t use it for every glaze, I’m a big fan of Shiva Half Tone Black, which is more finely dispersed than opaque colors like titanium white or ivory black. Half tone black allows your layers to show through – muting the colors, but leaving them alive, so that they have a beauty that’s all their own.” Molnar likes to save his real power punch of color for the end, pushing the paint to the limit with high key colors. If he needs a “turbo boast” or can’t match the color he’s trying to create with the pre mixed colors, he mixes powdered pigments with a few drops of Shiva Casein Emulsion. When all the layering and glazing is complete and the casein has dried, Molnar applies varnish over the painting to seal the surface. To intensify the color and produce a resemblance to oils, he opts for Shiva Casein Varnish or gloss acrylic varnish. To preserve that “authentic casein” look, he uses matte acrylic varnish.

Michael Boss
Michael Bass was introduced to casein about 25 years ago. “Although I’ve painted with oils and acrylics over the years, casein’s still my favorite medium. I feel I can control the colors better than when I’m painting with oil, and acrylics just don’t feel as alive as casein.”
Boss generally paints on Crescent Illustration Board with a rag surface and frames the finished work under glass to protect it. “I usually put a semi-opaque wash over the surface of the board and block in the composition. I can easily move things around or makes adjustments because casein dries so quickly that it’s easy to change things. When I’m happy with the composition, I generally begin working on the sky because that’s where the light comes from. As I move though my paintings, I blend while the casein is still wet to create the effects I want.
“Most of my paintings are a combination of thicker opaques and more translucent layers, which I build up with thin washes. The beauty of casein is you can paint transparent over opaque because the ‘fat over lean’ rule of oil painting doesn’t apply.” To keep his casein from drying out, Boss stores it in the refrigerator and he has also developed a “wet palette” to keep it from drying out overnight. “To make a wet palette, you’ll need two butcher’s trays,” explains Boss. “Line the first butcher tray with paper towels which should be soaked with water and kept damp at all times. Then put parchment paper, which is non-absorbent, on top of the wet paper towels and squeeze out your casein. When you’re finished painting, cover your palette with the other butcher’s tray and your casein will last for days.”

Stephen Quiller
“I work with acrylics, casein, watercolor, and gouache because they’re compatible, yet have different characteristics that lend themselves to different aspects of a painting. “I use casein because I love its velvety matte qualities and I find it’s the perfect medium for depicting the low winter light in the mountains around my gallery and home in Creede, Colorado.”
Quiller often does plein air paintings, but for the pieces he’ll work on later, he makes bold drawings in black crayon and makes notes about color and values. Then back in his studio, Quiller sets to work on 300 lb. watercolor paper. “When approaching a casein and acrylic painting, I usually begin with acrylics because when used transparently, they have a rich, vibrant glow and hold their intensity after they dry. “I tone my paper with thin luminous washes that tint the paper, rather than sealing it, so that when I come in with casein, the casein will bind to the paper. As I progress through the painting, I leave areas of the acrylic underpainting exposed so that I can use casein opaquely to diffuse the acrylic and create a cloudy veil. If I want I can also use casein for translucent layers, light over dark. Normally, I work with complementary colors, cool over warm or vice versa.” Although Quiller normally paints on watercolor paper, he’s recently been experimenting with textured claybord, a relatively new painting surface consisting of a hardwood panel coated with a PH neutral and acid free absorbent kaolin clay ground. “Painting on textured claybord is very much like ‘true fresco’ painting, which is basically building up layers of paint on a wet plaster surface,” explains Quiller. “With claybord, you can lift the paint and it’s very forgiving, although first time users should be warned that the paint does sink into the porous surface and may take some getting used to. “I find claybord responds well to all the water media I use including casein and it has a beautiful visual quality that’s all its own. Another advantage for water media painters is that claybord can be varnished and shown without glass.”

Douglas Wiltraut
Douglas Wiltraut is the President of the National Society of Painters in Casein & Acrylic. Yet, oddly enough, Wiltraut had never tried painting in casein until Jack Richeson approached him for this article. Rising to the challenge, Wiltraut came up with a casein painting five weeks later using the same technique he uses for his egg tempera paintings. Wiltraut agreed to share his experiences, not only as a first time user, but as a senior artist as well.
For his surface, Wiltraut prepared a “true gesso” panel – a Masonite panel sized with rabbitskin glue and primed with prepared gesso powder mixed with water – which is the same surface he uses for his egg tempera paintings. “As I squeezed out the paint, I felt like I was going back in time to when I did my last acrylic painting. I thought I was coming home to something familiar, but to my surprise, the consistency of the paint felt buttery and more workable than acrylic. “Because I rely on numerous glazes to create the illusion of strong sunlight and cast shadows in my work, I thought it was going to be an interesting challenge to paint with a medium that is more traditionally known for its opaque qualities. Once again I was pleasantly surprised. “I discovered I could paint thinly with casein, using just a bit more water than I normally use for glazing with egg tempera, while still using a dry brush technique. I was able to cover large areas in a shorter time with my glazes, which like watercolor or tempera, I built up from light to dark. “I was also able to use casein’s opaque qualities when necessary, which came in especially handy when I needed to do the lettering in the painting.” Wiltraut did note that casein had a tendency to sink into his “true gesso” surface, which is more porous than acrylic gesso, but found that after applying a coat or two of casein, the gesso seemed to seal. He also said the values dried a bit lighter than he expected, but as he became accustomed to the paint, he made adjustments for the value changes.
“Every medium has its own challenges, but I liked casein and I would certainly use it again, ” comments Wiltraut enthusiastically. “I especially liked the way I was able to build up glazes until I had a very interesting dry light – like the kind of light you would find in an old attic. I think this could be very useful for creating still lifes and interiors when I wanted to accomplish that old, dry, dusty look. “I’m sure there’s a lifetime of discoveries with this wonderful medium.”

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