[ Student Projects, Pigments and Binders]

The Effects of Plaster Dampness on the Color Quality of Frescoes


Contents


The Sistine Chapel, Michaelangelo




Abstract


History


About Our Project



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.


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.