Turnsole
Encyclopedia
Turnsole or folium was a dyestuff prepared from the annual plant Crozophora tinctoria ("dyers' crook carrier", from its use and the curved tip of its spike of florets).
starting with the development of the technique for extracting it in the thirteenth century, when it joined the vegetable-based woad
and indigo
in the illuminator's repertory. However, the queen of blue colorants was always the expensive lapis lazuli
or its substitute azurite
, ground to the finest powders. According to its method of preparation, turnsole produced a range of translucent colors from blue, through purple to red, according to its reaction to the acidity or alkalinity of its environment, in the chemical reaction, not understood in the Middle Ages, that is most familiar in the Litmus test.
Folium ("leaf"), was actually derived from the three-lobed fruit (illustration), not the leaves. In the early fifteenth century, Cennino Cennini, in his Libro dell' Arte gives a recipe "LXVIII: How you should tint paper turnsole color" and "LXXVI To paint a purple or turnsole drapery in fresco." Textiles soaked in the dye vat would be left in a close damp cellar in an atmosphere produced by pans of urine
. It was not realized that the oxidizing urine was producing ammonia
, but the technique reminds us how foul-smelling was the dyer's art.
The colorant was downgraded to a shading glaze and fell out of use in the illuminator's palette by the turn of the seventeenth century, with the easier availability of less fugitive mineral-derived blue pigments.
Turnsole was used as a food colorant, mentioned in Du Fait de Cuisine which suggests steeping it in milk. The French Cook by François Pierre La Varenne
(London 1653) mentions turnsole grated in water with a little powder of Iris.
Herbal
s indicated that the plant grows on sunny, well-drained Mediterranean slopes and called it solsequium ("sun-follower") from its sunflower
-like habit of turning its flowers to face the sun; alternatively it might be called "Greater Verucaria"; early botanical works gave it synonyms of Morella, Heliotropium tricoccum and Croton tinctorium.
History
Turnsole became a mainstay of medieval manuscript illuminatorsIlluminated manuscript
An illuminated manuscript is a manuscript in which the text is supplemented by the addition of decoration, such as decorated initials, borders and miniature illustrations...
starting with the development of the technique for extracting it in the thirteenth century, when it joined the vegetable-based woad
Woad
Isatis tinctoria, with Woad as the common name, is a flowering plant in the family Brassicaceae. It is commonly called dyer's woad, and sometimes incorrectly listed as Isatis indigotica . It is occasionally known as Asp of Jerusalem...
and indigo
Indigo
Indigo is a color named after the purple dye derived from the plant Indigofera tinctoria and related species. The color is placed on the electromagnetic spectrum between about 420 and 450 nm in wavelength, placing it between blue and violet...
in the illuminator's repertory. However, the queen of blue colorants was always the expensive lapis lazuli
Lapis lazuli
Lapis lazuli is a relatively rare semi-precious stone that has been prized since antiquity for its intense blue color....
or its substitute azurite
Azurite
Azurite is a soft, deep blue copper mineral produced by weathering of copper ore deposits. It is also known as Chessylite after the type locality at Chessy-les-Mines near Lyon, France...
, ground to the finest powders. According to its method of preparation, turnsole produced a range of translucent colors from blue, through purple to red, according to its reaction to the acidity or alkalinity of its environment, in the chemical reaction, not understood in the Middle Ages, that is most familiar in the Litmus test.
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...
. It was not realized that the oxidizing urine was producing ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
, but the technique reminds us how foul-smelling was the dyer's art.
The colorant was downgraded to a shading glaze and fell out of use in the illuminator's palette by the turn of the seventeenth century, with the easier availability of less fugitive mineral-derived blue pigments.
Turnsole was used as a food colorant, mentioned in Du Fait de Cuisine which suggests steeping it in milk. The French Cook by François Pierre La Varenne
François Pierre La Varenne
François Pierre de la Varenne , Burgundian by birth, was the author of Le Cuisinier françois , the founding text of modern French cuisine. La Varenne broke with the Italian traditions that had revolutionized medieval French cookery in the 16th century...
(London 1653) mentions turnsole grated in water with a little powder of Iris.
Herbal
Herbal
AThe use of a or an depends on whether or not herbal is pronounced with a silent h. herbal is "a collection of descriptions of plants put together for medicinal purposes." Expressed more elaborately — it is a book containing the names and descriptions of plants, usually with information on their...
s indicated that the plant grows on sunny, well-drained Mediterranean slopes and called it solsequium ("sun-follower") from its sunflower
Sunflower
Sunflower is an annual plant native to the Americas. It possesses a large inflorescence . The sunflower got its name from its huge, fiery blooms, whose shape and image is often used to depict the sun. The sunflower has a rough, hairy stem, broad, coarsely toothed, rough leaves and circular heads...
-like habit of turning its flowers to face the sun; alternatively it might be called "Greater Verucaria"; early botanical works gave it synonyms of Morella, Heliotropium tricoccum and Croton tinctorium.
External links
Further reading
- Daniel V. Thompson, Jr and G.H. Hamilton, 1933. De Arte Illuminandi: The Technique of Manuscript Illumination (New Haven: Yale University Press) pp 41-43.