 The eighteenth- and nineteenth-century restoration attempts were also reversed.Since it had proved impractical to move the painting to a more controlled environment, the refectory was instead converted to a sealed, climate-controlled environment, which meant bricking up the windows.Then, detailed study was undertaken to determine the painting's original form, using scientific tests (especially infrared reflectoscopy and microscopic core-samples), and original cartoons preserved in the Royal Library at Windsor Castle.