[ Student Projects, Pigments and Binders]
The Effects of Plaster Dampness on the Color Quality of Frescoes
The Sistine Chapel, Michaelangelo
The purpose of our experiment is to determine whether frescoes should
be made with wet or dry plaster, and if the color quality would be affected
by the dampness of the plaster. We would also like to determine if pigments
made from red earth that we collected work as well as pre-processed pigments.
Frescoes are an ancient form of painting on plaster. Frescoes have provided
many historians with insights into ancient cultures, such as Greece, Italy
and the Byzantine Empire. The origins and development of frescoes are unclear,
but there are some that date back to 79 A.D. Around 1300-1800, Italy became
the most skilled and influential culture in the art of fresco. Most early
frescoes were buon frescoes, an Italian term meaning pure. In buon frescoes,
the pigments were applied directly to wet plaster, therefore the artist
had to work very quickly so as not to allow the plaster to dry. Earth pigments
were the most popular for painting, and a wash called sinopia was used
as a base. In the 15th century, painters began to experiment with techniques
to shorten time and allow greater flexibility. Longetivity was often sacrificed
as a result, such as in "The Last Supper" by Leonardo daVinci.
Some of the greatest fresco work was done by Michaelangelo on the Sisting Chapel ceiling. The 19th century proved to be a time when fresco use died down, however, it was revived in the 20th century by artists such as Diego Riviera.
About Our Project
We believe that the wet plaster, when painted on, will bind better with
the pigments than the dry plaster. We also believe that the collected pigments
that we make from natural earth will bind better with the plaster than
the processed pigments because they contain sand, and when doing research
we read that sand was a sort of binder used in ancient frescoes.
L*A*B READINGS FOR PIGMENTS
|vermillion||wet plaster: L:48.93, a:+5.23, b:+5.82|
dry plaster: L:54.51, a:+12.17, b:+8.08
paper: L:59.32, a:+39.68, b:+20.84
|ultramarine||wet plaster: L:55.46, a:+2.05, b:-7.62 |
dry plaster: L:50.11, a:+6.07, b:-13.37
paper: L:47.79, a:+27.78, b:-60.47
|green earth||wet plaster: L:58.12, a:-3.07, b:+8.59 |
dry plaster: L:50.26, a:-5.69, b:+9.77
paper: L:79.39, a:-8.43. b:+15.13
|vertigris||wet plaster: L:54.37, a:-9.05, b:-0.25|
dry plaster: L:44.23, a:-9.57, b:-6.69
paper: L:82.66, a:-14.52, b:-8.02
|yellow ochre||wet plaster: L:60.83, a:+.95, b:+19.13 |
dry plaster: L:54.51, a:+4.39, b:+21.93
paper: L:83.35, a:+2.19, b:+37.39
We conclude that there are greater amounts of color as measured by the
L*a*b scale on the dry plaster than the wet plaster. There appears to be
more pigment on the dry plaster. The pigment on the wet plaster was always
brighter in terms of the L on the L*a*b scale than the pigment on the dry
plaster. This could be for two reasons. First, we learned that there would
be a chemical bond between the pigment and the plaster and that it would
result in luminosity (brightness of a pigment). It could have also been
the white of the plaster mixing with the pigment to produce brighter L*a*b
results. It was concluded that the color quality on the dry plaster was
much better. The pigments bound better with the wet plaster but the color
quality was not as great.
Slides and Descriptions
RED EARTH SAMPLE 1-(anisotropic) viewed with cross polarized light.
RED EARTH SAMPLE 2-also viewed with cross polarized light.
Pigments painted on plaster after drying for five days.
Pigments painted on plaster after drying for three hours.
Our final attempt at producing an aethestically pleasing and durable fresco.
We would like to thank Cassie Mansfield and John Bordley for their heaps of assistance concerning this project. -dfs and rln
Rachel Nance, Danielle Steves, 1997.