Working procedure – Painting on glass
.jpg "da G.B. Salvi")
.jpg "da Bourne Jones")
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After cutting the glass tiles, we draw the sketch using black grisaille. Then, using soft brushes and brown grisaille, we lay the shadows to create volume and depht. |
| There are major technical difficulties in the process of laying the shadows because glass doesn't absorbe color. After the painting is done, we perfectly clean the reverse and those spots that will be completely transparent. Then we fire the tiles at 600 degrees Celsius. This temperature allows for the pigments to permanently adhere to the glass. |
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After the first firing, the brown grisaille sometimes fades a lot, therefore we need to re-establish the shadows and also finish the minute details. It is at this point that we apply the polychrome enamels, which add colors to the panel. In the following photographs, you can see the application of the yellow enamels to the hair of the figures and to the tunic of the Risen Christ ('Cristo Risorto'). At this stage the enamels are opaques, but they will become transparent after the next firing. |
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After re-establishing the shadows, we clean the tiles again and set them on the kiln trays. These trays are made of non-stick material, and we cover them with a dusting of calcium carbonate. |
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| As you can see in the photograph, the trays are piled up until the kill is full, then the firing procedure begins. We gradually raise the temperature so it reaches the optimal level in about 8 hours. |
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Then, after a brief lapse of time, the kiln is turned of, but temperature must decrease much more slowly than it was raised. Lest dangerous internal tension happen in the glass tiles, which would make the tiles break. Two days elapse before we can see the results of our work. |
