Table 1.
Different samples regarding their porosity and conductivity were used for the experiment. MS1 and MS2 are not conductive, while MS3, RS1 and RS2 have some metallic particles (iron) in their pigmented layers.
| Sample | Pigment | Preparatory layer | Binder | Number of Layers |
|---|---|---|---|---|
| MS1 | – | Chalk | RSG | 1 |
| MS2 | – | Chalk | LO | 1 |
| MS3 | Yellow earth | Chalk | RSG + T | 2 |
| RS1 | Green earth | Chalk | Oil U + T | 3 |
| RS2 | Yellow and green earth | Mortar | Carbonaceous | 4 |
MS: Model sample; RS: Real sample; RSG: Rabbit skin glue; LO: Linseed oil; T: Tempera; U: Unknown.