C80 is a technique using an Acryloid B72 solution that was developed specifically for the Sistine Chapel restoration. The idea that a substance might be left on the frescos was denied, so the restorers had to find another way to do a final treatment. The C80 method is a way to consolidate the pigments without the formation of a superficial layer. Restorers would apply the Acryloid B72 only in areas attacked by salts and where extreme detachment of rare pigments occured. A few coats of Acryloid B72 would be applied and restorers would let them dry over a two day period. When the two days had passed, the small portion of treated fresco would be washed with one stroke of a flat brush soaked in a potassium solvent. Immediately after the thinner, the area would be washed with distilled water and a natural sponge. The process is only done once. Once the treatment is completed, a subtle heightening of tone has occured and the fresco will appear as if untreated. The pigments and intonaco are perfectly waterproof and the detached pigments are secured.