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Applying Multiple Layers of Pigment to Create a FrescoSusie Clark |
I originally became interested in working with pigment as part of my final project and specifically how pigments are incorporated into frescoes. Originally I had planned to compare and contrast two differnt types of fresco: true fresco and al secco; however, due to time constraints and the delayed delivery of the slaked lime, I ammeded my project to compare the color quality of different layers of pigment in true fresco. Though this was not part of my original plan, I found the results very interesting.
Fresco is an ancient technique that comes from the Italian word for fresh in which pigments are applied to wet plaster. First used by the Romans in the first and second centuries BC, this form of art remained heavily popular because it not only covered the walls, but also became a part of the walls themselves. Not many examples of the ancient technique still remain entact; however, with the discovery of Pompeii in mid-eighteenth, the development of technique and design have become more and more evident. A re-emergence of frescoing occurred during the Italian Renaissance. From the walls of a nobleman’s country estate to the famous Sistine Chapel ceiling, frescoes were in high demand. Much more information is known about these later artists’ techniques and the pigments used. The artists must apply the pigment to plaster while it is still wet to create a true fresco. He would work only in small sections that measure about one square foot. These sections are known as giornata. Today the plaster is formed by mixing sand with slaked lime putty to create a "canvas" for the artist.
Materials:
Natural pigments:
Chromium
Oxide Green
Vine
Black
Smalt
Iron
Oxide Yellow
Iron Oxide
Red
Slaked Lime—Slaked
in 1998
2 frames with
mesh wire bottoms
2 clay tiles
approximately 2x2 inches
Diamond trowel
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The first layer, trusilar, which is formed by combining course sand and slaked lime in a 2:1 mixture is placed in the base of frame and spread using a diamond trowel. The layer is then scored with a cross-hatching pattern and then allowed to dry. |
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The second layer, arricio, is made by mixing medium sand and slaked lime in a 2:1 mixture. It is added on top of the first layer and is spread and smoothed using a trowel. This layer dries until the sand does not stick to the hand when lightly pressed against the surface. |
The final layer, intonaco, is made up of slaked lime and fine sand combined in a 1:1 mixture and placed over the top of the second layer and smoothed. n.b. Because of the time constraints while working on the top layer, the two frescoes were made during two different sessions |
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Pigments must have already been combined with water prior to the mixing and spreading of the final layer. The paint should be a very thin and diluted mixture. |
| Once the final layer is spread, the artist must work speedily to apply the pigments while the plaster is still wet. | |
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Layers of pigment are applied in deliberate brushstrokes of diminishing size, one on top of the other, so as to show the different layers of pigment |
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Once the final layer has dried, a colorimeter is used to measure the difference in color. |
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In addition, I experimented with two clay tiles as an alternative to the frame with wire bottom. To these I applied a thin arricio layer and a thin intonaco layer. One was successful, the other one was not. |
Observations
| First Layer | The first layer, which was formed by combining course sand and lime was very gritty and very thick, but when dried the rusty color of the sand appeared much more white than expected due to the dried slaked lime. |
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| Second Layer | The second layer, in many ways very similar; however, the final layer was applied while it this layer was still a little damp. It appeared also very orange because of the color of the sand and was also very gritty |
Final Layer |
The final layer, because it was a different ratio of sand to lime, was less sandy and gritty than the previous two layers. The first mixture of lime and sand was still not of a satisfying consistency, so in the second mixture I increased the amount of lime and decreased the amount of sand ever so slightly. The result was much more satisfying and produced a better finished product. |
| Pigments | The pigments were mixed with water to make the "paint" very thin. The final mixtures of pigment and water closely resembled the concentration of paint in watercolors. |
| Applying Pigments | When applying the pigment, thin layers are used. Because the first fresco I made was much more sandy than expected, making the application of pigment very difficult. The fresco seemed to wick the pigment and water solution into the wet layers, making a lasting image |
| Finished Fresco | The finished product was different than I had expected. The first fresco was still sandy and slightly gray in color, yet it did not seem to effect the color of the pigment. The second fresco cracked in a few areas, but the overall surface appearance of the fresco was much more polished. The difference in the layers of pigments was visible. |
| Tiles | The tiles were not overly successful. One crumbled completely during the application of the final layer. The one tile that I was able to apply both the arricio and intonaco layer, still was very difficult to work with. |
Results/Data
| Color | One Layer of Pigment | Two Layers of Pigment | Three Layers of Pigment |
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| Black | L* 53.92 |
L* 37.28 |
L 36.52 |
| Yellow | L* 72.24 |
L* 67.22 |
L* 60.50 |
| Red | L* 48.50 |
L* 39.92 |
L* 36.69 |
| Green | L* 65.00 |
L* 52.47 |
L* 47.88 |
| Blue | L* 57.30 |
L* 56.12 |
L* 53.06 |
Data was collected by using a colorimeter to produce a L*a*b* reading. The letters refer to coordinates on a 3 dimensional plane. The L* values show lightness, while the a* and b* refer to color. The data suggests that the L values decrease with the increased layers of pigment, this conclusion is supported by visual observation. It seems that in order to achieve a darker and deeper color, the artist should apply multiple layers of pigment. The
Image of Sistine Chapel courtesy of ARTstor
Gianluigi Colalucci: "Fresco" Grove Art Online. Oxford University Press, [04 April 2007], http://www.groveart.com/
Kleiner, Fred and Mamiya, Christin. Gardner's Art Through the Ages. Wadsworth Publishing; 12th edition 2004.
I would like to acknowledge Dr. Bordley for his help on this project and for providing me with several resources that pertained to the production of frescos.