====Preparing Wood Panels for Icon Painting====A work still in progress, spelling & punctuation issues etc.

By, Lady Oksana Goncharova

The process for making the wood panels for painting is a detailed process. Wood panels were used for egg tempera painting in medieval times. Later during the Renaissance, the wood panels were also used for oil painting. Wood is more permanent than alternatives. Icon paintings were done using egg tempera paints. The egg tempera is a mixture of ground pigments that are tempered with egg yolks and water.1)

Both monks and lay artists painted icons in the 14th and 15th centuries. Icon painters of this time worked for a growing number of patrons including; monarchs and rulers, feudal lords, nobles and bishops.2) Many of the artists started signing their work in the 14th century. The surviving icons were found in churches and wealthier households, usually depicting a religious theme.

The first step for icon painters was to prepare a wood panel on which to paint. Cennino says to use whitewood or poplar, linden or willow.3) Birch, maple and oak are also used.4) The wood must be thoroughly dry before starting to prepare the panel, taking several years.5)This was done to insure that none of the tree saps would leach onto the paint surface. For larger icons, planks of wood are glued together using cheese and a little quicklime.6) this mixture is very sticky and dries as hard as stone.7) Use of horizontal and vertical strips of wood, attached to the back, further supported the planks.8) For smaller icons these strips were not used. The wood panels could be left flat or carved. This carving could be as simple as a framed in area being cut out to elaborate leaves, animals or other ornamentation. Detailed ornaments would be carved seperately and then attached to the panel with nails or pegs. Cennini tells us to cover any nail heads with a little “coin” of tin foil stuck on with glue. This was done so that no rust would come through to spoil the gesso finish.9)

A size made of sheep parchment is then applied. The sheep parchment was boiled until one part remained out of three. When the size is sticky it is done.10) This was then strained and more water was added and then heated again. The resulting glue size was then applied to the wood and any ornaments, using a brush. Three coats of size are used, letting each coat dry in between. After the size has dried take strips of old thin linen or canvas that is white and soak them in the size.11) This size is thicker than the first size, made with more glue than water. These strips can be small or large depending on the size of the panel. take these strips and lay them out on the panel, flattening them out with your hand and removing any seams.12) Let this dry for two days. After the panel has dried, scrape down any lumps or seams using the tip of a knife shaped like a spatula.13) Linen was laid down to strengthen the panel, especially when boards are glued together. If the panel cracked or any joint came apart the linen would hold the panel together and keep the gesso from cracking.

The next step is to apply several layers of “gesso grasso,” which is a thick gesso. This is made with plaster of Paris and the sheep parchment size. The plaster of Paris is purified and sifted like flour.14) It is then ground up with the size on a slab of stone. The result is a thick paste. This mixture is then scraped on the flats of the panel using broad even slices. It is applied with a spatula or a wooden slice, which is a chisel-edged slip of hard wood.15) The gesso is worked into the grains of the linen. It is applied in layers in alternating directions. Warmed gesso grosso is used on the carved areas. The gesso becomes liquid when slightly heat. This makes applying coats to carved areas easier, without losing any details.

Gesso Sottile can be applied at this point. This gesso is thinner gesso than the gesso grosso. It is made from gesso grosso, which has been purified by soaking for a month. After stirring every day for a month pour off the water. Make this into loaves and allow to dry. Cennini says, “this is sold to painters by the apothecaries.”16) This gesso is used for gessoing, for gilding and doing reliefs.17) These loaves are then soaked in water again and ground on the stone slab. Put the ground gesso in a cloth and wring out any wetness. Put this into the top of a double boiler and mix in the parchment size. Make sure not to overheat, just barely liquid is fine. This is brushed on top of the thicker gesso in layers. The application of gesso sottile is not necessary, it can be skipped. It is more time consuming, but doesn’t require any scraping after drying, as this makes the surface quite smooth and perfect for painting.18)

The panel is then left to dry for two days. Ground up charcoal is placed in a cloth bag and dusted over the gessoed panel. The panel is then scrapped down. It is scraped using “little hooks”. Cennini describes the “little hooks” as having a straight edge and one finger wide.19) The charocoal is used to see where it needs to be scraped down. Keep scraping until the panel is white again.20)

What I Did

Step #1: Picking the wood. I used a piece of poplar wood. No gluing was involved. I did a flat panel with no ornamentation. No support system was needed.

Step #2: Applying the glue size. I used already prepared rabbits skin glue. I did not need to boil down sheep parchment. The glue is reconsitutied by sprinkling the glue pellets over water and letting it soak for several hours. The result is a slightly chunky applesauce like consistency. I used a 5% glue solution (5gm of glue to 100ml of water). I used a weak solution so that the glue would be absorbed into the grains of the wood and seal the panel. The reconstituted glue was then put in a water bath in a glass container. Double boiler method would work also. The glu melts a 98 degrees. I never let the glue get above 110 degrees. I used a thermometer to monitor the water temperature. Heating the glue over 120 degrees spells disater and a lumpy, sticky mess. (Pervious experiment) this means just barely turing the heat on the stove. The glue will eventually melt at the 98 degree mark; it can’t be rushed by application of more heat. The glue was stirred occasionllly. The glue will become clear, with no visible grains. I took the melted glue still in the water bath off the stove and applied the glue to the wood while still war,m. The glue stayed melted for a long time in the water bath even off the stove. I drenched the panel on all sides using a brush to apply the glue. This was then allowed to dry for several days.

Step #3: Applying the linen. I picked a light colored open weave linen as closed weaved fabrics trap air and are hard to glue down. I pre-washed the linen and dried it so that it would be pre-shrunk. I cut the piece slightly larger than the panel. The glue solution was made the same way as step #2. This time I used a 15% glue solution, (15gm of glue to 100ml of water). Once the glue was melted the fabrics was put in the melted glue to soak for 1/2 hour. I rolled the fabric and then folded it, before inserting into the glue.After the fabric was soaked it was removed and the excess glue was squeezed out with my fingers. It was fairly wet, but not dripping. I laid the fabric out over the bottom of the panel and rolled it out, and flattened the fabric using my fingers. I flattened from the middle to the edge and gradually un-rolled the fabric to the top flattening as I went. I made sure there was no creases or air bubbles. If there are ant dry spots the melted glue must be applied to those areas so the fabric will adhere. The panel was then let to dry overnight. The excess linen was then easily cut off the edges using a razor blade. This was then let to dry another 2 days.

Step #4: Making the gesso. Once again the glue solution is prepared as above using this time a 10% solution. This time a larger container was used to accept the whiting. To the glue solution I added a tablespoon of linseed oil and honey. These were used in making gesso for Flemish painters. It made the gesso less susceptible to cracking.21) I used whiting instead of plaster of Paris. Cenninis’ plaster of Paris is made from alabaster and or gypsum, which are forms of calcium sulphate. I used ground chalk and marble dust. The chalk is a calcium carbonate.22) Marble dust ans size was used by painters in Bologna in the 14th and 15th centuries.23) Chalk was often used to make gesso in the middle ages.24) I mixed 1/3 marble dust to 2/3 of chalk to make my whiting. They were blended well together and then I measured out 8 cups of whiting per 1 liter of glue solution. After the heated glue solution was clear the whiting was sifted into the warm solution. This was done slowly using a kitchen sieve and letting the whiting “Snow” into the solution. Scoops of whiting were added to the sieve and each layer of whiting was absorbed before the next spoonful was added. The gesso was not stirred until all the whiting was introduced and absorbed. Then the gesso was gently stirred, being careful not to introduce air to the mixture. The mixture was then transfered to a storage container and a wet cloth was put directly on the surface. The container was then put in a cool place to set up. The gesso can be kept for month in the refrigerator.

Step #5. Application of the gesso. The gesso is used at room temperature. (If it was refrigerated, allow to return to room temperature before using). Slabs of gesso were sliced off and put on a plate with a wet cloth on top to keep the gesso moist. Using a putty knife I applied the gesso. Chips of gesso were sliced off and mashed into the fabric and smeared down in a stripe towards myself. the panel was coated with the gesso in lineal strokes. Any lines from the putty knife were smoothed out using my fingers. The panel was then dried before the next layer was put down. Each layer is put on rotating the panel so each layer is in a different direction. After five layers th e texture of the linen fabric will disappear. After that less and less gesso is applied. After ten layers were applied, the panel is allowed to dry for several days.,

Step #6. Sanding of the panel. Streaks, if there are any, are removed using a blade of some sort. I used a straight edge blade. The panel was then carefully sanded using a 220 grit sandpaper to start, then 320 grit, and then 400 to polish. A barely damp cloth was then wiped over the surface to remove any gesso dust.

Bibliography

Babic, Gordana. Icons. International Publishing GmbH/ Munich. 1998.

Cennini, Cennino d’ Andrea. The Craftsman’s Handbook (Il Libro dell’ Arte, 1437) translated by Daniel Thompson. Dover Publications, 1954.

Merrifeld, Mary P. Medieval and Renaissance Treaties on the Arts of Painting, orginal texts with english translations. Dover Publications. 1967.

O’Malley, Maryann, (My Icon teacher)

Sulatn, Altoon. The Luminous Brush painting with egg tempera. Watsin-Guptill Publicatiosn. 1999.

Talbot Rice. Russian Icons. Spring Books. 1964.

Thompson, Daniel. The Practice of Tempera Painting. Dover Publicatiosn. 1962.

Thompson, Daniel. The Materials and Techniques of Medieval Painting. Dover Publications. 1956.