- Turnsole
The dyestuff folium or turnsole, prepared from the annual plant "Crozophora tinctoria" ("dyers' crook carrier", from its use and the curved tip of its spike of florets), was a mainstay of medieval manuscript illuminators from the development of the technique for extracting it in the thirteenth century (Thompson and Hamilton 1933:41). It joined the vegetal-based
woad andindigo in the illuminator's repertory, but the queen of blue colorants was always the expensivelapis lazuli or its substituteazurite , 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 theLitmus test ."Folium" ("leaf"), was actually derived from the three-lobed fruit, not the leaves. In the early fifteenth century,
Cennino Cennini , in his "Libro dell' ArIe" gives a recipe "IXVIII: How you should tint paper turnsole color" and "ILXXVI 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 ofurine . It was not realized that the oxidizing urine was producingammonia , 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 itssunflower -habit of turning its flowers to face the sun; alternatively it might be called "Greater Verucaria"; [So named in a recipe for producing the colorant, "Pro tornasolio faciendo",British Library , Sloane Mss 1754, folio 235 verso, quoted in Daniel V. Thompson, Jr., "Medieval Color-Making: Tractatus Qualiter Quilibet Artificialis Color Fieri Possit from Paris, B. N., MS. latin 6749", "Isis" 22.2 (February 1935, pp. 456-468) p 458 note. ] early botanical works gave it synonyms of "Morella", "Heliotropium tricoccum" and "Croton tinctorium".Notes
External links
* [http://www.debrecy.org.uk/raphael.exe/turnsole.htm Turnsole]
* [http://www.geocities.com/CollegePark/Library/2036/art/pgpnt.htm Merouda Pendray, "Pigments and paints" 1999]
* [http://www.pbm.com/~lindahl/articles/food_coloring_agents.html "Food Coloring Agents"]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.
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