Digital BW, The Print

Léonard de Vinci's 500 year old painting, "La Jaconde" aka "Mona Lisa"
has found a new home at the Musée du Louvre, Paris and will be again
shown to the public starting today.

Vinci's famous painting will be shown with Veronese's painting "Les
Noces de Cana" and with other 16th century Venetian paintings  in a
new room called "La salle des États", designed by architect Lorenzo
Piqueras.

Mona Lisa has undergone a series of tests: microfuorescence X
analysis, Raman microspectrometry, and spectrocolometry. Verdict: Mona
Lisa is in very good health for its age. There is an ancient slit
measuring 11cm that goes from the upper side to Mona Lisa's right
temple. It has not evolved and seems stabilized.

They have found that the pictural coat is so fine as to be almost
unreal, evoquing the preciosity of ancient chinese paintings made from
color juices. The finesse of the coating goes against all rules of
security for an oil painting.

It's the varnish that maintains the painting at the cost of it being
darkened. There was talk of lightening the varnish but this has been
rejected as being too dangerous as the solvent might attack the pigments.

Varnish protects and adds to longevity but at the same time, darkens 
the images

Cheers,
Andre Moreau

Andre,

Interesting news -- thanks for the post.

 
> Léonard de Vinci's 500 year old painting, "La Jaconde" aka "Mona Lisa"
> ... will be again shown to the public starting today...

> Mona Lisa has undergone a series of tests:...
> Verdict: Mona Lisa is in very good health for its age. 
>...
 
> They have found that the pictural coat is so fine ...
> goes against all rules of security for an oil painting.

Which, I assume, is that thicker coats will resist fading more?

> It's the varnish that maintains the painting at the cost of it being
> darkened...

Do they know what the varnish is?

This reinforces my view that the coatings are very important, at least
potentially protecting the pigments from physical abrasion, oxidation and
other gas attacks, and UV.  I suspect the high-tech clear coatings will
continue to get better for some time.

(But the real significant point is that Dan Brown in "The Da Vinci Code"
totally missed the symbolism of the coating both protecting and obscuring Da
Vinci's encoded message about the Holy Grail!!)

Paul
www.PaulRoark.com

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul Roark"
<paul.roark@v...> wrote:

> 
> Do they know what the varnish is?
> 
Paul,

Sorry I do not have that information at this time. I'll try to see
what I can find out.

It seems that Da Vinci mixed his pigments with a highly volatile
binder which evaporated as soon as it dried. This is more visible in
the veil. The painting seem to have been painted on a wood panel,
whose fibers may be visible under close scrutiny. I wonder how lignin
 could have affected its longevity, if it did.

There is no visible brush strokes on the painting. Coud be that Da
Vinci spread the pigments with his fingers.

And, I made a typo, it should have read "La Joconde".

Cheers,
Andre Moreau

Paul,

I dont know if I'll ever know which varnish Da Vinci used. My
knowlegde of chemistry is very limited. Here's what I've been able to
  get. Hope this is of any help.

Varnish is made up of binders (resins, oils, gums), solvants such as
alcohol and eventually diluants or other additives like colorants. But
you probably know that.

Da Vinci probably used varnish made from natural resins. 

But, what seems just as important, if not more, is the method of
applying the varnish. When not mixed with the pigments, it was applied
in several coats. When done correctly it will last. If not, bubbles
and/or premature cracking will appear. The different varnish coatings
can be distinguished under UV lights.

Even if applied coorectly, cracks will eventually appear in the
varnish from natural ageing or from stress of shocks. Mona Lisa was
painted on a board and in 1951 a perimetric frame made of oak was
installed on the back side. I wonder how cracking of the varnish could
be prevented on a photograph which by nature has a flexible support.

The other problem is yellowing. In 1999-2000 a grand was given by the
C2RMF to the Université Blaise Pascal,France  for research on the
prevention of yellowing of varnish, but I don't know if any progress
was made.

I wonder how long the Mona Lisa painting would have lasted if it had
been subjected to todays airborne pollutants and UV levels from day
one. It is now displayed behind glass in a controlled atmosphere.

And finally, museums do have conservationist which are able to prolong
the life of artworks which would have deteriorated a long time ago.

HTH,
Andre Moreau