17

Bianca that Cillenia Trissino

Bembo,37

his second wife, was so taken by the
beauty of the portrait and by the grandduchess’s features that she had tried several
 times to kiss

it.38
In the opinion of his contemporaries, Francesco Bembo was a »vain man, of little
reputation, profuse in speech but very limited in noteworthy

assets«.39

He was
accused of having passed on state secrets to the grand duke of Tuscany while he
was Provveditore ai Dazi from 1591 to 1593. This office allowed access to the
Senate and so to the effective centre of the Republic’s government. At the end of
his mandate Bembo continued to send information procured by deceit until he
was found out and reported to the Council of Ten. Bembo confessed to the crime
and was condemned to death; on 5 July 1599 he was beheaded between the two
columns in the

Piazzetta.40

A Blue in a Class of its Own

The specialist literature has always taken for granted that the portrait of Bianca
Cappello now in the Kunsthistorisches Museum is the one discussed in the correspondence
 between Bianca and Bembo, partially published in 1981 by Karla Langedijk
 in her monumental work on Medici

portraits.41
Thanks to a valuable clue contained in the correspondence between the two
people it is now possible to confirm with certainty that our portrait is precisely
the one commissioned by Bianca Cappello. In a letter of 5 November 1585 Francesco
 Bembo, who was in Firenzuola, on his way back from Rome to Venice, includes
 a reminder by Pulzone to Bianca that contained a request to procure some
ultramarine blue. Bembo’s desire to own the portrait was so great that he allowed
himself to pass on the artist’s request to

Bianca.42

It was common practice that
the commissioner provided the painter with the most precious materials and ultramarine
 blue, made from lapis lazuli, was a very expensive pigment. Such information
 with first hand »technical«

details43

could be scientifically verified. So it
was decided to subject the areas of the painting that according to the restorers’
analysis seemed to contain significant quantities of blue pigment to x-ray fluorescence
 spectroscopy. This study showed the presence of ultramarine blue beyond
any doubt and, on the basis of these results, it is possible to confirm the identity
of the painting commissioned and owned by Francesco Bembo as that in the
collections of the Kunsthistorisches Museum.