Rembrandt's 'recipe for a stopping-out varnish'

Rembrandt's 'recipe for a stopping-out varnish' on the verso of a drawing 'Landcape with a River and Trees', 1654-55.

• "..in order to etch, take white turpentine oil, and add half the turpentine to it; pour the mixture into a small glass bottle and let it boil in pure water for half an hour".

It is evident that Rembrandt refers (alas fragmentarily) to a so-called 'stopping-out varnish', used to terminate the bite of acid in select areas of a plate that had already been exposed to the etching agent.

Thus other portions will remain exposed to the acid to deepen the bite.

Seven Colours of the Rainbow

A rainbow is an optical phenomenon caused by refraction, internal reflection and dispersion of light in water droplets resulting in a continuous spectrum of light appearing in the sky.

The rainbow takes the form of a multicoloured circular arc.

Rainbows caused by sunlight always appear in the section of sky directly opposite the Sun.

Rainbows can be caused by many forms of airborne water.

These include not only rain, but also mist, spray, and airborne dew.

Jean-Léon Gérôme | La République, 1848 | Musée des Beaux-Arts de la Ville de Paris, Petit Palais

Eastman Johnson | Co-founder of the Metropolitan Museum of Art

Eastman Johnson (1824-1906) was an American painter and Co-Founder of the Metropolitan Museum of Art, New York City, with his name inscribed at its entrance.

Best known for his Genre paintings, paintings of scenes from everyday life, and his portraits both of everyday people, he also painted portraits of prominent Americans such as Abraham Lincoln, Nathaniel Hawthorne, Ralph Waldo Emerson and Henry Wadsworth Longfellow.

His later works often show the influence of the 17th-century Dutch masters whom he studied while living in The Hague, and he was even known as The American Rembrandt in his day.

Francois Fressinier, 1968 | Figurative painter

Born in Cognac, France to scholarly portrait photographer parents with an affinity for aesthetics, it was fitting that modern figurative artist, François Fressinier, would develop a unique, enchanting style.

His father's admiration for the works of the Old Masters and his exposure to some of the world's most historic places, along with France's Gallo-Roman ruins and Gothic churches inclined François to explore and create figurative, symbolic artwork.

In addition, his education at the Ecole Brassart in Tours afforded him the opportunity to study the drawings and paintings of old and new masters.

Eberhard Keil | Pupil of Rembrandt

Eberhard Keil or Keyl dit Monsù Bernardo (1624-1687) was a Danish Baroque painter who became a pupil of Rembrandt.

Keil was born in Helsingør.

According to the RKD he was a pupil of the Danish painter Morten Steenwinkel, who became a pupil of Rembrandt in Amsterdam in the years 1642-1644.

Guy Hoff (1889-1962)

Born in Rochester, New York and trained at the Art School of the Albright Gallery in Buffalo and the Art Students League in New York City, Guy Hoff (1889-1962) is known for his cover pages for The Saturday Evening Post, McCall's and Ladies Home, among others, which often star young, beautiful women.

Guy Hoff is among the American painters who also used their talent to design illustrations for books, magazines and newspapers during the so-called 'Golden Age of American Illustration'.

Konstantin Razumov, 1974 | Children's world

Konstantín Rázumov (Константин Разумов) is a Russian painter with a realistic-impressionistic tendency.

He began his studies in art and painting in the studio Ilyá Glazunov at the Academy of Fine Arts in Moscow.

Razúmov is faithful to early Impressionism; however, he adds some modern touches, which are most evident in his beautiful, charming, soft and sensual figures.

Giovanni Boldini | Treccia bionda / Blonde Braid, 1891

Giovanni Boldini | Blond Braid, 1891

Based on its messy and impulsive pictorial style, "Treccia bionda" is generally dated to the beginning of the 1890s, by which point Giovanni Boldini (1842 -1931) had already moved to Paris.

In addition to serving as an example of Impressionist painting from that time, the faintness of the strokes showcases an in-depth knowledge of Frans Hals' chiaroscuro technique; it seems that Boldini may have become close with him during a trip to Amsterdam in 1876.

Unlike many of the artist's female portraits, in which the entire figure functions as a means of showcasing all the details of the protagonists' elegant and elaborate dresses, this painting limits the appearance of the figure to the bust.

Giovanni Boldini | Treccia bionda, 1891 (detail) | GAM - Galleria d'Arte Moderna di Milano