The problem lies in the analysis and understanding of the techniques utilised by Michelangelo, and the technical response of the restorers to that understanding. A close examination of the frescoes of the lunettes convinced the restorers that Michelangelo worked exclusively in "buon fresco"; that is, the artist worked only on freshly laid plaster and each section of work was completed while the plaster was still in its fresh state. In other words, Michelangelo did not work "a secco"; he did not come back later and add details onto the dry plaster.