Friday June 28th

Today we spent the day mainly with Andreina Nardi, Roberto's wife and well known consevator. She first took us through the traditional Roman process of making lime mortar. To begin, blocks of  limestone and arranged into a large kiln, also made from limestone, and a fire is lit at the base of the kiln. The following reaction takes place: calcium carbonate plus heat yields calcium oxide (quick  lime, which is very reative with water) plus carbon dioxide. The smoke from the kiln turns black when the temperature reaches roughly 700 C, and the kiln is sealed off  for three to  four days, until the smoke turns back to white.

After allowing a week for the kiln to cool off, the stone is removed and water is added along the following reaction: calcium oxide plus water yields calcium hydroxide. The stone must sit in the water for about three months; if the correct proportion of water is added, hydraulic lime is produced, but with extra water slaked lime (also called lime putty) is produced. Filler  is then added, often sand but sometimes shell, pumice, straw, or coal, depending on what the mortar will be used for. Finally, the mortar is applied and pigments must then also be applied while the mortar is still fresh.

Andreina then taught us a little about tratteggio, a form of inpainting areas of loss in paintings and painted surfaces, and showed us incredible examples of her own use of the technique. We then spent some time working on our Medusa mosaic and working on selecting pictures, videos, and music for the final video of our time here in Italy.