I disagree with those who assert that Titian and El Greco painted on a tempera underpainting. ...In contrast to Titian, El Greco very frequently employed glazings ...In El Greco we find a curious combination of tempera school ideas associated with a freedom of the brush stroke surpassing that of his master, Titian. Like the tempera painters, El Greco often underpainted in grisaille and glazed upon such a monotone underpainting the fiery hues of madder lake, verdigris, azurite blue and yellow (probably Indian yellow). This... largely accounts for the brilliance and extraordinary luminosity... But El Greco's grisaille... was brushed on roughly and the texture of the superimposed color often does not correspond with that of the grisaille. This... is an entirely unorthodox method. Entirely unconventional also was his use of the madder, which, at times, he applied with an extreme impasto defying the nature of this glazing color.