Troubleshooting Chalk Gesso

December 14, 2010

The first time I began creating paintings on panels using chalk gesso I had no problems. I read the manuals, ordered the materials from a good supplier in NYC and proceeded to create my panels.  No problem. It was summer in Connecticut.  30 years on, the paintings I created from those panels are still alive and well.

Over the years, with other batches both in sunny, dry, warm California and later in Germany (also in the summertime), I had no problem. My batches were done using rabbitskin glue sourced from my American art suppliers (Utrecht in NYC or Bay City in SF) or later Kremer pigmente in Munich. Now, after moving to Bruges, I’m back to creating new batches of gessoed panels.  But why am I experiencing such difficulty with my gesso? How strange to find myself returning to square one with what should be a relatively simple process. So, I’ve decided to document my trials and errors – for myself and internet posterity.  There may be others out there who have experienced similar problems?

The problem:

My assembly process would begin normally, but as I proceeded to build up layers, the gesso would no longer flow but rather glom onto the panel. The brush would stick, the gesso would glob.  When dry, a little sandpaper would remove far too much pigment. So it was clear: there was a problem with my glue.

Troubleshooting:

I generally create my panels in the wintertime.  Nothing to be done about that.  The house is radiator heated, that’s got to be better than whatever (winter) conditions Cennini ever experienced. We live next to a canal in an older house that does not contain double glazed windows, so it might be more drafty and moist than many modern environments, still, creating good gesso panels should be possible.

Double boiler?  Yes, of course. Did the glue boil?  No.  Never.  But after the gelatine melts, what is the threshhold temperature which spoils the glue?  I researched temps on the internet and found 52° Centigrade to be the most generally noted gauge.  But is that true?  From my experience, it depends on the source, as RS can vary a great deal.  At this point, I would not go by numbers but rather my own eyesight.

For example, a few years ago I bought a new batch of glue from my local art dealer, a man who specialized in esoteric artists materials.  It seemed OK at the time but then the problem began to recur.  Does RS have a shelf life?  Or did I let the glue “cook” too long?  I had purchased a meat thermometer and kept my temp well below 52°.  Still, invasion of the glom. 

For my most recent batch I used the last of my old RS from the esoteric art supply store.  When I added the pigment, the paint became very granular and unattractive.  I guess it does have a shelf life (even though it did not smell)…  So I threw it out.

Then used the RS that I had purchased recently from Kraemer Pigmente.  Little crystalline pebbles, very nice.  When I ran out of the Kraemer RS (silly, I had only purchased a 100 G test amount), I bought a new batch of glue from my local art supply store (brand, Senellier). This stuff comes in pellets similar to the scat of small animals that you might find in a forest. (I prefer the Kraemer)  But for both glues, I soaked them overnight (80 G RS to 1 liter of water), melted, cooled and did the finger-pressure-crevice test. So far, so good. (Though the Kraemer RS seemed firmer, clearer, less cloudy, more uniform and refined.)

I bought an electric warming plate at the local Kringwinkel (Salvation Army).  It holds food warm but doesn’t  cook it.  40° Centigrade or so but not higher.  Great, I thought.  But still, when I kept the glue-pigment in that double boiler pot for a few hours, the glue lost its strength.  Oooops.

Bottom line: 

  • Buy the best grade of RS that you can find from an archival artist’s materials supplier (like Kraemer). 
  • Do the crevice test, if you want, but be sure to take it off the heat as soon as it fully melts.  
  • Add your pigment in the center in a stream, allowing it to gently absorb the glue and sink via gravity.  
  • Stir thoroughly but not vigorously.  
  • For uniformity, do your gessoing in one session (one day). 
  • Rabbitskin glue is an organic substance, containing all the resilience and receptivity of living matter, as well as it’s limitations.

OK, OK, I admit it.  I am in love with glazing.  Like non-duality, it has the capacity of unifying many disparate elements, without negating them.  (And isn’t that  wonderful???)  As ever, translucency is the key.  But the tricky thing is the application.  Too much glazing and the painting has a tendency to float off the panel; too little and the thick opaque paint just stays stuck in the mud, reflecting little or no light.  Of course, you can see the same principle reflected in people’s lives. Too little inspiration and we have the tendency to stay stuck in our comfortable grooves; too much inspiration – without a transparent application to the mundane activities of living – and that wonderful poetry, lacking substance, falls short of its mark.

Korte Sint Annastraat

Korte Sint Annastraat value study

I have admired this very colorful alley view of the Sint Anna Kerk in midday light for a number of years now.  Over time, I have made watercolor and value studies of it,  photographs, too (here is the all important value study). The light at midday creates a strikingly vertical composition. The color relationships of the tile roofs are quite exciting along with the added bonus of it being the only street in Bruges whose street is lined with bricks glazed in blue ceramic. Over time, I collected enough material for a winter studio production this year.

Korte Sint Anna black and white

Korte Sint Anna black and white


I began the piece by transposing my black and white drawing to a 30 x 60 cm. gessoed panel. I like to use silverpoint for the first level of drawing. It is very soft and can render lots of intimate details. It tends to create an ambience that invites image development. Silverpoint catches well on the toothy gesso, so the mark lands and does not require too much repetitive movement. Then using india ink, I add touches of higher contrast that push forward the gesture of the composition – but only in the foreground. The idea is to build up the visual effects of distance from the get go. Every layer will play a role. So the black and white level sets up the basics. I’ve decided to add “I Am” to the sky. (the decision occurred after I made the photograph, so Photoshop has come to my display rescue)

Korte Sint Anna Egg tempera

Korte Sint Anna Egg tempera

I use egg tempera to set out the basic color relationships. In contrast to the methods of the old masters, who used their underpainting primarily for value work, I bring color in early in order to test out the vibrations – particularly of complimentary colors. I use a limited palette and usually avoid any color mixing on the palette – with the exception of white since I add zinc white to all my colors in order to avoid an oversaturated final painting. At this stage, the colors are light and somewhat pastel-like. With this method of painting, by the time you reach the oil level, you cannot really paint white over a color to lighten it very much as each successive layer adds a layer of darkness, so to speak. You have to to rely as much as possible on the original white of the panel (that’s why I call it painting backwards). When I’m finished with egg tempera, I seal the surface with a light coat of (rabbitskin) glue size.

Korte Sint Annastraat

Korte Sint Annastraat mixed technique #1

Oil painting with the mixed technique essentially involves alternating transparent glazes with opaque pigments mixed into a painting emulsion. I start with a yellow glaze and then set out bringing the highlights back in. Yellow paint mixed in a series of tints up to white goes back into areas that will contain differing degrees of that color. Warm Gray mixed up in an array of tints is worked back in to shadow blocks, or alternatively into areas of color that will not contain much yellow. At this point, using a large brush, I try to cover most of the panel with emulsion mixed paint. The work goes quickly. In a few hours, I have set the groundwork for both hue and value development. The overall effect is harmonious and low contrast. Because emulsion has been mixed into the paint, the areas of paint blend smoothly into adjacent areas and will dry to the touch within a few days.

Korte Sint Annastraat

Korte Sint Annastraat mixed technique #2

Between the yellow and the red layer, I decided that the “I Am” text in the sky needed to be more luminous, so using turpentine and a stiff brush, I took the earlier levels of paint away (painting backwards). The text may now seem rather stark but I know that it will be softly blended by the time I am done. On the palette I mix up a series of tints in yellow, red and warm gray. There are about 15 little blobs of paint. I cover the panel with a thin glaze of Crimson Lake and begin working the colors back into the surface. Reclaiming the highlights is best done by removing the red glaze rather than painting emulsified white paint back into it (more painting backwards). Shadows and other colors receive their appropriate tint (the normal approach of painting forwards). Every area should receive some work; if glaze is not painted into, it can become unreceptive to further manipulations in successive layers.

Korte Sint Annastraat

Korte Sint Annastraat mixed technique #3

The final level is the blue level. I mix up a series of tints of yellow, red, blue and Payne’s Gray (at this stage I switch from Warm Gray to Payne’s as it is more neutral). Now I have about 20 little blobs of paint. I cover the panel with a light glaze of Cyan. This pigment is quite saturated so I am careful to dilute it well and begin painting. I “erase” the glaze from all the strongly highlighted areas. The warm colors of the underpainted tile roofs pop out and glow (very nice!). I reclaim all the neutrals by painting a gray tint back in, beginning from the background and moving forward. Additional colors arise as needed with a brushstroke of the appropriate color. For example, the strong greens of the foreground shadow, left, are aided by its underlying yellow color structure. Soon I have covered most of the panel and am working details back into the foreground. This is the last session: it takes the longest time since it combines the blue color adjustments along with the final gray balance work. I finally step back, satisfied and ready for dinner.

Comments, as usual are welcome…

Encaustic

May 26, 2009

Encaustic:

portrait in encaustic

portrait in encaustic

Interestingly, encaustic or hot wax painting,  was known as one of the major creative techniques used by the Greeks.  The Egyptian tomb portraits, which are some of the finest examples of encaustic portrait painting available today, were done by Greeks (not Egyptians) – according to Ralph Mayer.  In recent times Jasper Johns used the technique with a great deal of success in his series of images of the American flag.  It is a technique that traditionally requires alot of cumbersome tools.  Today the process has been streamlined with simpler tools but for purity, simplicity, and honesty’s sake I will try to describe the technique that I have used.

The Ground:
The Greeks reportedly used encaustic on walls and panels.  A revival of the technique in the 18th/19th century concentrated mostly on mural painting – with reportedly insubstantial results, now 200 years later.  My own experience has been entirely on wooden panels, prepared with chalk gesso as for egg tempera.

Tools:
As the medium is melted beeswax, the first tool one needs is a pallette for mixing the colors in a molten state.  Years ago, I went to my local metal junk yard and commissioned a pallette measuring 18″ x 28″ of 1/4″ steel plate welded on four sides by legs 5″  high (also of 1/4″ steel plate).  This allowed for the pallette to sit on top of a hot plate with an air space of approximately 2″.  At the time, I remember it cost me about $10.  The second tool one needs is a hotplate.  The best are the kind that allow for variable temperature adjustments.  Look around at your local flea markets and you should be able to find what you need. 

Materials:
The same dry pigments that can be used for egg tempera can be used in encaustic.  Purchase a few blocks of fine beesawax.   Melt some wax and mix it with approximately 20% damar varnish by volume.  Mix this molten fluid together with a similar amount of dry pigment and keep it in a metal cup on the warmed pallette.  Mix up a few colours as needed for the project at hand and keep them warm on the pallette. [I hear these days that encaustic sticks can be purchased with the resin/oil component already mixed in.]

encaustic flag by Jasper Johns

encaustic flag by Jasper Johns

Painting:
Molten colors can be applied using bristle brushes or even the pallette knife.  As the paint hardens almost immediately upon contact with the panel, expect a highly textured, immovable result. [My original experiments were done outside in the hot humid summertime, so setting time was slightly delayed anyway.]

Burning In:
Further manipulations can be obtained by heating  the panel surface with a heat lamp.  Be careful to keep the surface horizontal to avoid runs.  The final “burning in” is also done with a heat lamp close and evenly rotated over the surface to achieve a final fused result.  In this way heavy impasto effects can melt into thin, veil like veneers. [I have never done this phase, I look forward to trying it.]

There are some other resources for encaustic.  One being the International Encaustic Artists website.  And here’s the information that is available on Notebook.

Egg Tempera

May 25, 2009

Egg tempera portrait by Botticelli

Egg tempera Medici Portrait by Botticelli

Egg tempera is an time tested technique, especially well loved by panel and icon painters.  It renders flat graphical shapes and fine precise detail quite well.  Softer gradual modulations are possible but take practice and patience.  The unvarnished final work has an almost chalk-like finish to it.  This technique formed the backbone-skill to any medieval or renaissance painter’s tool chest. The twentieth century has witnessed its revival with Andrew Wyeth being perhaps its most famous spokesman.

For anyone wishing to ask experts geeky questions about the medium check out the MITRA forum. In the past there has also been the Society of Tempera Painters (whose informative forum is currently offline). The Tempera Society had a well established site and forum, documenting many aspects of the process as well as related techniques. In its absence, I’d suggest picking up a good book and starting in. The online version of Daniel Thompson’s, The Practice of Tempera Painting is one of the most extensive sources around.  Cennini is charming even if a bit antiquated in his terminology and procedures.  If you are looking for something more general in order to get started, try Ralph Mayer’s “The Artist’s Handbook of Materials and Techniques”, Reed Kay’s “The Painter’s Guide to Studio Methods and Materials”, or “The Materials of the Artist and Their Use in Painting” by Max Doerner.  All are tried and true comprehensive source books for the craft of painting.

Egg tempera is a paint made from an emulsion of oil and water.  The final paint film is not as flexible as oil.  Thus, to avoid cracking, the painting is executed on a firm and stable panel not on a stretched canvas.  At the moment, I use egg tempera primarily as an underpainting.  The links here on the right offer some info – by no means extensive – about how I prepare my gesso and panels.

Pigments:
Be sure to supply yourself with a good collection of dry pigments – avoiding poisonous materials whenever possible.  You don’t want to breathe in toxic dust. By grinding your own paints you get to know the specific characteristics of each pigment – opacity/translucency, saturation, hydrophobic or philic, chromatic nuance. Online suppliers are very helpful if you do not live in a large city with a big art supply store. Get a thick piece of frosted plate glass and a glass muller. Otherwise a pallette knife and wooden painter’s pallette can suffice in a pinch. Grind up a small amount of each pigment you want to use in distilled water, making a smooth paste. The pastes can be stored in plastic film containers for short periods without drying out. To extend that drying out time I usually insert a piece of sponge at the top of the jar. Keeping it moist prolongs the life of the pigment paste.

The Egg:
Locate as fresh an organic an egg as you can. Crack the shell carefully in half without breaking the yolk. Carefully move the yolk between shell halves to isolate the yolk from the white (all the while protecting the egg yolk membrane from puncture).  Let the white albumen drip away. Pass the yolk back and forth between the palms of the hands in order to dry it off.  Roll it across a piece of absorbent paper towel for further drying.  Eventually you should be able to pick up the yolk by it’s sac.  Hold it over a small clean jar (empty jelly jars from hotels are great for this) and pinch the bottom.  The pure yolk will drip out.  Add an equal amount of distillled water, cap, and shake it. Store in the refridgerator.

Tempering the Paint:
On your glass palette add equal amounts of pigment paste and egg yolk. I use a palette knife to measure a “bean” of pigment paste and a small pipette to measure the same by dipping into my prepared egg. Mix until smooth. If you have already ground up your pigments in distilled water, then adding the egg binder now is easier and requires much less grinding. Some pigments will require more yolk, others less. To make sure you have tempered your paint correctly, Take a moistened sable brush, dip it in your newly mixed paint and lay a stroke on a nearby piece of window glass. It should dry quite quickly. Then take a one-sided razor blade and gently scrape the paint swash off. It should maintain its own consistency and curl off like a ribbon. If you have not added enough egg the pigment will return to powder and flake off. If you have added too much egg the paint film will lack chromatic saturation. Let experience be your guide. Soon you will get the knack of it.

When you are satisfied that you have tempered your paint correctly, transfer this mixture to a painting cup. I use a nested set of porcelain dishes that have a top cover. The tempered paint is rather thick, too think for painting, so at this point it is important to add additional water in order to arrive at the right mixture of pigment/yolk. How much water? Apparently, that doesn’t really matter. If your paint has been tempered correctly you can (if you wish) dilute it with large amounts of water so as to paint with many fine watercolor-like washes. As you work, it may seem as though the color is not building, but be patient and you will see that it does.

Painting:
Sable brushes dipped in this watered down paint will be too saturated for the painting stroke. Using your thumb and forefinger press the excess liquid out until the brush renders a clean full stroke without leaving behind a blob of paint at  the end of the motion.

Egg tempera does well with many light thin strokes. Do not immediately rebrush a stroke. Let it dry, then add another level. Because it dries so quickly this is usually not a problem at all. In this way soft transitions can be achieved. But is is important to let your brush dance over your whole painting. Do not obsess in any one area, if it has not thoroughly dried it can become overworked and lift off earlier levels of paint, creating a hole that is difficult to repair. Stay light and playful, attentive to the whole work. Each artist decides how to use this medium to his/her own ends.

Silverpoint

May 15, 2009

Hans Holbein silverpoint

Hans Holbein silverpoint

Silverpoint is another ancient technique that is receiving renewed attention these days.  Jan van Eyck and the Flemish masters are reputed to have regularly used it as a drawing tool. Artists like Picasso and Joseph Stella brought it into the 20th century art world.  The final design stands softly but well on its own or can be incorporated as an underdrawing into a painting. 

There is an informative site at silverpointweb.com which offers a lot of practical information as well as sales of silver tips and a ground for the drawing support.  I bought some of my pure silver tips from him a few years ago. The silver renders a soft, warm gray line that can darken upon exposure to light – just like the silver content of a photograph. The line itself is indelible so it cannot be erased.  Another experiential resource is international silverpoint archives.

Drawing with silver is a very simple but time consuming technique.  A thin piece of silver is inserted into a drawing stylus instead of a piece of lead.  The silver can be obtained from a local silversmith. I have used both pure silver and sterling. The pure silver is reputed to create a slightly darker line, but I have not yet noticed the difference (which could be due to my gessoed surface not having enough tooth, so take my experience with a grain of salt). Points can be chiselled fine or beveled. Darker tones are achieved by repeated gestures and not by an increase in pressure. 

silverpoint Joseph Stella

silverpoint Joseph Stella

The drawing surface seems to make a great difference in results. The surface should have a slight “tooth” to it, to draw out the silver particles. I have used both white gessoed panels and toned paper. The toned watercolor paper clearly had the tooth to pull out the silver, but the value of the silver was so close to that of the paper that I finally opted for the white panels.  Thus far the panels have given fine results which I have then used as underdrawings for some of my paintings.

Gesso

May 9, 2009

Various recipes exist for gesso. Here’s what I use:

The Glue:
Dissolve 2 3/4 ounces of dry rabbit-skin glue with one quart water in a big glass jar (used pickle jars are great for this). This equates to 75 grams dry glue to approximately one liter of distilled water. The proportions work out to approximately 10/1 water to dried glue by volume. Many professional egg tempera painters suggest a higher percentage of 16/1. (I will try this next time around.)

Let it soak overnight.

Heat the glue in a double boiler, that is, with a second pan surrounding the jar with the glue water. The water should be the same temperature as the glue water, so bring the heat up slowly to melt the gelatine glue. Stir gently. The glue should never boil, only melt. Overheating significantly harms the adhesion of the glue, so do not let the temperature rise above 135 F° (57.3 °C), 127F° (53°C) is optimal.

The Filler:
Use calcium carbonate or precipitated chalk or whiting for filler with 10% titanium white or zinc white to insure a bright whiteness to your gesso.  The chalk whiting part can vary in both purity and whiteness, depending upon the grade. Industrial grade chalk whiting can be found in most hardware stores or paint shops. Dry pigments can be found at art supply shops or online suppliers. 

The proportions are 1 lb filler (or 450 grams) to one quart (liter) of glue water.  Or 1 1/2 filler to 1 glue water by volume. The melted glue is gently poured into the chalk stirring all the while.  Lumps should be stirred or strained out (cheesecloth).  The final result should be about the consistency of light cream.  Return the mixture to the double boiler, to keep it warm but again, be careful not to let it boil.

Applying the Gesso:
Sand the panel lightly to remove any rough texture, clean the dust off with a moist cloth.  Cover the board with a light coating of size (1 1/2 oz rabbit skin glue dissolved in one quart water or 45 grams glue to one liter).  After the size has dried, begin applying thin coats of gesso.  The first coast is loosly brushed or scumbled in. I prefer to apply the gesso to both sides and ends of the panel to avoid the uneven absorption of moisture that can cause warping. I use a wide flat bristle brush, applying thin layers in alternating horizontal and vertical layers.  The layers dry quickly, especially in warm weather.  Generally a well prepared panel can take about 10 thin coats of Gesso. I wait until 3 or 4 levels have accumulated and begin lightly sanding it down between layers, and then using a moist cloth to remove all dust.

Finishing:
After the final coat, the sanding moves from coarse to fine.  As a last step, it’s possible to take a slightly damp cloth and rub it gently over the entire surface in circular motions in order to obtain a final smooth, egg shell-like finish.  If, however, the intended underdrawing will be in silver point, it is best to leave that last step out in order to retain a slight tooth to the panel.

The Panel

May 7, 2009

The Panel:
A firm non flexible ground is necessary for painting with egg tempera.  On good linen canvas, the oil medium can sustain flexing and shrinking, but egg tempera cannot.  If one chooses to work exclusively in oil, canvas may be the ground of choice.  As I prefer to use a mixed technique, painting on panel is my preference.  Additionally, I find the smoothness of the surface very sensuous.

Of the choices readily and economically available to painters these days, my personal preference is good quality, plywood panels.  They are heavier than Masonite but in the long run, more absorbent.  They do not warp, and the fine crackles that can occur in the gesso from slight wood expansion can be avoided either by obtaining a high quality piece of plywood from a cabinet maker or by gluing a thin layer of fine linen fabric to the board before the first coat of gesso.