Lime Cycle is the process by which limestone or marble (pure form of lime stone) is converted to quicklime by heating, then it is slaked (hydrated), and reverted back to limestone (marble) by carbonation.
Lime Plaster is composed of slaked lime (calcium hydroxide) and an aggregate such as sand, mixed with water. In Western culture scholars are dating lime plasters as far back as to 4th century BC.
It was widely used in Ancient Rome where it came from Greece. Greek origins of Roman Plaster are mainly responsible for its mixture proportions of 1 part lime 1 part fine aggregate for the final color coat (referred to as marmorino). During the Renaissance the mixture proportion of the final color coat was changed to more painting friendly proportion of 5 parts lime to 8 parts aggregate. Technically, the proportion itself did not change, rather the final, marmorino coat of polished plaster was omitted and painting began to be done on finely troweled undercoat. I believe that at this point, to distinguish the difference in plaster finish, the “new final” painting plaster coat began to be referred to as “Intonaco” assuming its’ name from the word “plaster” – “Intonaco” in Italian. Hence – “painting on wet plaster.”
Complete Lime Cycle:
CaCO3 + heat → CaO + CO2 → CaO + H2O → Ca(OH)2 → Ca(OH)2 + CO2 → CaCO3 + H2O
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