Before any restoration work was attempted, scientist were allowed in to do chemical analysis on the frescoes. By running certain tests, scientists were able to confirm that Michelangelo worked the majority of the fresco in buon fresco using a secco only when impossible to do otherwise. Scientists also found the frescoes covered in heavy layers of foreign materials that had built up over five hundred years. Smoke from candles, torches and braziers, greasy dust, sediment from rain, glue, animal varnish, and residue from past cleanings had built up on the frescoes. Scientists also investigated the cracks in the ceiling and determined them to be the result of a shifting foundation. Scientists identified two major restorations that had occured: the 1570 Carnevali and the 1710 Mazzuoli. Carnevali's restoration was carried out in almost all fresco while Mazzuoli's was executed in tempera.