The Mona Lisa is restored by Jean-Marie Hooghstoel, who is responsible for restoration of paintings for the galleries of the Musée Napoléon. A wash and revarnishing is undertaken, which involves cleaning with spirits, a touch-up of colour, and a revarnish.
Two butterfly-shaped walnut braces are inserted into the back of the panel of the Mona Lisa to a depth of about 1/3 the thickness of the panel. This intervention is was skillfully executed, and successfully stabilized the crack that had been forming in it.
The upper brace of the Mona Lisa panel falls out. A later restorer glues and lines the resulting socket and crack with cloth.
Louvre restorer Eugène Denizard performs watercolour retouches on areas of the paint layer of the Mona Lisa disturbed by the crack in the panel. He also retouches the edges of the picture with varnish, to mask areas that were covered initially by an older frame.
The Comtesse de Béhague gives the Mona Lisa its current frame, a Renaissance-era work consistent with the portrait's historical period.
Vincenzo Peruggia attempts to sell the Mona Lisa to the directors of the Uffizi, and is caught. The painting is exhibited around Italy for two years before being returned to the Louvre.
After the return of the Mona Lisa after its theft, Eugène Denizard is again called upon to work on the painting. Denizard cleans the picture without solvent, and lightly touches up several scratches to the painting with watercolour.
A flexible oak frame with beech crosspieces is added to the Mona Lisa. This flexible frame, which is used in addition to the decorative frame, exerts pressure on the panel to keep it from warping further.
Part of the Mona Lisa is damaged when a vandal throws acid at it.
The Mona Lisa is damaged again when a rock was thrown at it, resulting in the loss of a speck of pigment near the left elbow. Restorer Jean-Gabriel Goulinat touches up the damage with watercolour.
Cross braces are added to the Mona Lisa to help to keep the panel from warping further. The beech crosspieces are switched to maple after it is found that the beechwood has been infested with insects.
A new insect infestation is discovered in the back of the panel of the Mona Lisa as a result of crosspieces installed to keep the painting from warping. This is treated on the spot with carbon tetrachloride, and later with an ethylene oxide treatment.
The spot on the back panel of the Mona Lisa damaged by insect infestation is again treated with carbon tetrachloride as a preventive measure.
A conservation and study team replaces the maple crosspieces of the Mona Lisa with sycamore ones, and an additional metal crosspiece is added for scientific measurement of the panel's warp.
The Mona Lisa is moved to a new location within the Louvre's Salle des États. It is displayed in a purpose-built, climate-controlled enclosure behind bulletproof glass. The humidity is maintained at 50% ±10%, and the temperature is maintained between 18 and 21 °C. To compensate for fluctuations in relative humidity, the case is supplemented with a bed of silica gel treated to provide 55% relative humidity. The painting is now illuminated by an LED lamp.
A new 20 watt LED lamp is installed, specially designed for the Mona Lisa. The lamp has a Colour Rendering Index up to 98, and minimizes infrared and ultraviolet radiation which could otherwise degrade the painting.
Extract a cover letter from Leonardo da Vinci to Sultan Bejazet (or Beyazid) II offering his services. This is dated by Charles Nicholl to July 3, 1503.
> I, your servant, have heard about your intention to build a bridge from Stanboul to Galata, and that you have not done it because no man can be found capable of it. I, your servant, know how. I would raise it to the height of a building, so that no one can pass over it because it is so high ... I will make it so that a ship can pass under it even with its sails hoisted.... I would have a drawbridge so that when one wants one can pass on to the Anatolian coast.... May God make you believe these words, and consider this servant of yours always at your service.
Orbital calculations suggest that on this day, Pluto moves outside Neptune's orbit, remaining there for 233 years.