Monday, June 18, 2018

Ancient Medium - Egg Tempera Painting, Part 6 - Care of Egg Tempera Paintings

Part 6 – Care of Egg Tempera Paintings

Since it is an organic medium, mildew can be gently wiped off with a moist cloth, applying a little physics to the genome of mold means it will disappear if the painting is placed in the sun for a few minutes and gently vacuumed with a soft brush attachment. Unlike oil, properly tempered egg and pigment will not develop the craquelure of aging on the surface as seen in old oil paintings.  Egg tempera colors are less likely to yellow although certain varnishes will yellow on egg tempera as on oil.  Egg tempera will also not fade as much as oil as long as lightfast pigments are used just as with oil.

Sustainability of the Substrate

In a recent article on egg tempera painting the author failed to mention that as important as the medium is to the painting, so is the substrate on which the painting is painted.  Proper preparation of the panels includes applying hide glue, tempering of the paint (grinding the egg mixture with the pigment) and the final curing all contribute to the longevity of an egg tempera painting resulting in few if any problems.  The environment in which the painting exists must also be considered.  Will addressing these issues completely protect a painting?  Probably not entirely, but they will greatly enhance the life of the painting. Consider what had to be done to bring two Leonardo da Vinci oil paintings to this country – Ginevra de’ Benci from Liechtenstein and Mona Lisa from France, both painted over 500 years ago.  Both had to adhere to elaborate environmental control procedures to prevent damage. Ginevra de’ Benci was the more difficult as it had resided in the same gallery of a castle in Liechtenstein for centuries.  The National Gallery in Washington, D.C. had their handler place a special climate-controlled case on the floor of the gallery in the castle directly below where the painting had hung for centuries.  The case was left open for days to a week before the painting was carefully packed and the controls set on the case.  It was then transported by air, but arrived on the east coast of the U.S. during a winter blizzard.  The plane was diverted which set all the wheels in motion for the case could not be opened in customs.  It was allowed to change to a new flight undisturbed.  When the painting arrived in Washington, D.C. the case was placed on the floor of the gallery where the painting would then reside and the controls were set to gradually adjust to the climate of the painting’s new home before the case could be opened and the painting hung in its new home.

Next Up, Part 7 – Conclusion:  Techniques – Craft as much as Fine Art!  (on June 18)

Monday, June 11, 2018

Ancient Medium - Egg Tempera Painting, Part 5 - Layers and Finishing

Part 5 – Layers and Finishing

Many layers of diluted pigment are used to create an egg tempera painting.  It takes approximately 100 layers to begin to see the substance of a painting (see section on Techniques for speeding up this process).  A finished egg tempera painting consists of about 300-500 layers (this can vary greatly depending on the subject matter, the technique and the artist).  In a recent article an author described the “very thin layers….” of an egg tempera painting as susceptible to damage.  I’ve not seen a report on how many layers the Old Masters actually used, but I assume their efforts were similar to today’s as both are based on similar pigments and their constituent properties.  Tempered and applied correctly there will therefore be many, many layers of pigment that, once cured, are very durable.  Dust and grime can affect an egg tempera painting just as it does oil paintings, but I doubt that it penetrates 500 layers unless some substance is poured on the painting or moisture is too high and the painting not protected in a suitable environment. This is also the case with oil paintings.  With normal wear and tear from hanging on a wall, an occasional dusting, very light vacuuming, moment in the sun, or damp sponge-path sets the egg tempera painting right again today!

Polishing the Painting

Like oil painting there is one last step.  With an oil painting this is typically a layer of varnish.  Once the egg tempera painting is complete and has dried for at least a few days to a week (better to let it cure, if you have the time, for a year), the final polishing is performed.  Using a cotton ball or cheesecloth the painter gently buffs in a circular direction over a section at a time until the entire surface of the painting has been polished.  If the paints were properly tempered then the end result is the most beautiful satiny eggshell finish that feels like microfiber or silk.  If the pigment has not been properly tempered then pigment will come off on the cheesecloth or cotton ball.

This can be the final step, although some painters follow it with a coating of varnish that restores the look of freshly applied paint just as it does with oil paintings, but varnish is not necessary with egg tempera. Other forms of finishing have been used but these two are the most basic.

Next Up, Part 6 – Care of Egg Tempera Paintings (on June 18)

Monday, June 4, 2018

Ancient Medium - Egg Tempera Painting, Part 4 - The Image and Applying the Pigment

Part 4 – The Image and Applying the Pigment

Starting an egg tempera painting on a clean gesso panel is a daunting process.  The gesso is highly absorbent and the first hundred or so layers of very diluted pigment vanish pretty quickly into the gesso, drying almost instantaneously. Lines drawn on traditional gesso once made cannot be erased, therefore, unless the painter is brave, works with a broad brush approach and understands the image and the medium, the image to be painted on the panel is usually planned out ahead of time, drawn on another surface, such as paper, and transferred to the panel. Before transfer papers the Old Masters would lay the drawing over the gesso or parchment and, using a sharp point dipped in ink, pierce the paper thus transferring the image as a series of dots. This can be done today using transfer papers and a stylus.  Another method is silverpoint (one of several types of metalpoint).  This was a traditional drawing method used by medieval scribes on manuscripts drawing out the image on parchment or a panel. The essential metals used were either lead, tin or silver, but today silverpoint is accomplished using a stylus with a small, fine rod of silver at the end that is drawn across the surface of the gesso making a mark.  This line is initially grey, turning to warmish brown as it is exposed to the air and the silver tarnishes. Silverpoint may remain as the final drawing or can then be painted.  The drawing can be transferred using the silverpoint step and then the painting begun.

Because the gesso is so absorbent layers of paint are built up gradually alternating warm and cool, light and dark, crosshatching and broad brush in a meditative fashion until the substance of the painting begins to emerge. The speed of this can be quickened by sponging or airbrushing the pigment on large areas such as sky or large color fields. Pigment is applied in greatly diluted strength because raw pigment is used without the buffer of layers of oily medium in between.  In egg tempera painting there is just the pigment, yolk and water.  If too strong a color is used there is often no going back, thus no way to correct a mistake as can be done with oil paint as it may take so many layers in egg tempera to lighten or darken that area that the paint becomes too impasto to be sustainable (impasto, as a technique, doesn’t work in the traditional sense of egg tempera painting).  Also, some colors are more intense than others and therefore cannot be corrected easily, if at all, such as using too much Prussian Blue, but some intense colors not formulated used as transparent hues can still be used as glazes if diluted sufficiently.  An egg tempera painter must know their colors, how the hues respond, the chemical makeup (toxicity) and how to use them effectively.

As already mentioned a respirator should be used when preparing the paint from dry pigment, but is not necessary once water has been added to create a paste.  Depending on how a painter works latex gloves may be necessary when working with toxic pigments for any length of time.

Depending on a number of factors (how the pigment is applied and the amount of tempering), the painter will occasionally gently sand the painting, or parts of it, during the process of painting with a very fine 2000 – 3000 grit sand paper.  An equally gentle buffing follows this sanding with cheesecloth or a cotton ball.  This removes rough spots, smooths out edges, or corrects insufficient tempering.  Too much buffing at this stage will limit adherence of future layers of paint so it is kept to a minimum.

Occasionally, if the pigment is too dry or wasn’t tempered enough, what’s known as a “nourishing layer” of yolk is applied to areas or to the whole painting.  This mixture is typically one part yolk to sixteen parts water and applied quickly over the intended area.

Next Up, Part 5 – Layers and Finishing (on June 11)