During the Medieval era, painters and artisans had to invent methods and adapt art materials to increase adhesion between canvas banners and the pictures painted on them.
At the beginning of the 13thC, the Venetian Senate declared a public holiday on the day before Ash Wednesday so everyone could go to confession before the beginning of Lent. In addition to confessing their sins on Tuesday, Christians enjoyed their final party for 40 days.“Carnevale” was celebrated in Italy, “Mardi Gras” in France with marvelous city-wide parties and air space filled with colorful flowing fabrics.
In Florence, Medici carnivals employed artists and artisans year-round to build and paint sets for various street parties and international performances to attract tourists. Early in the Medieval era, the flying of heraldic banners was a privilege only for royals and bishops who were in attendance.
Between the 12thC and 15thC, the display of a heraldic banner became, more indicators of personal prosperity than social status. As the middle class expanded, patrons and customers wanted even more richly embellished banners with newly purchased clan insignia embroidered with colorful flowers.
Embroiderers could not keep up with demand for stylishly encrusted banners. To meet escalating demand, artisans traded time-consuming embroidery for painting to speed up production. Painted banners could be made more quickly and less expensively. If lost, they were easier to replace. Painters needed specialty paints in order to make pictures to stick on fabrics blowing in the wind.
Originally, banners were made from simple woven cloth, usually dyed a solid color. The fabric used commonly for banners was linen. Linen is woven from long fiber threads from the stalk of flax plants, the seeds of which yield linseed oil. Industrially produced linen “sail cloth” was value-priced, durable, and readily available. In Venice, banners had been painted with Christian iconography since the First Crusade. Carrying cloth banners in religious processions was much easier than carrying life-sized plaster statues through the streets.
Banners were used to brighten interior walls where murals were not an option. (Fresco painting was not common in Venice due to high humidity.)
Inside or outside, to make painted pictures stick onto flowing surfaces, painters and their advisors (chemists, alchemists, pigment distributors) had to develop materials that would form a more durable, more flexible paint film than tempera or distemper (limewater) paints. Venetian color makers met the moment and invented an oil painting system which proved to be a durable art-making medium.
To prepare fabric surfaces for oil paints, a canvas was fitted into a frame to hold the fabric taut. The new painting system relied on gesso plaster for the foundation layer. Both sides were sized with a custom formulation of thin gesso (calcium carbonate + gypsum plaster pigments mixed to the correct viscosity with lime water + warm hide glue). The calcium carbonate “marble dust” + quick-set gypsum filled the holes between the warp and the weft threads without making the fabric too heavy.
Oils paints were never new. Oil paints have been made from some concoction of linseed oil, pine resin, and beeswax for thousands of years. Among the first cultivated crops 12,000 years ago, the seeds of the flax plant yield linseed oil. Ubiquitous in human life, linseed oil was used as a base for medicines, ointments, and lotions; as well as sealants for mosaics and binders for paints. Linseed oil is the only naturally occurring vegetable oil that dries completely into a firm film. Different jobs required specific modifications of oils to change viscosity and dry time. Oil paints for banners were made with low viscosity.
As a binder for health care and for cosmetics, linseed oil was produced from the first pressing of the seeds, using no heat. For painting, linseed oil was further modified with pine resin (1 C fine-quality linseed oil mixed with ¾ cup very finely crushed pine resin).
To make thin layers, painters could defat the oil a bit by adding a dash of solvent like “naft” or “naptha.” Naft was the highly volatile, highly flammable liquid hydrocarbon mixtures from petroleum refined by distillation beginning about 4500 years ago in the Akkadian culture in Mesopotamia. Naft was used as a diluent and to make Greek fire. (Turpentine was not widely available as a diluent until the 18th century.)
Being able to thin oil paints decreased the oil slick and increased the likelihood of good adhesion. The goal was to use enough binder so pictures would stick on banners without being too heavy. Banners had to fly to signify which dignitaries were in attendance or to signal where to locate your fellow soldiers on battlefields
While much more expensive, silk was a popular fabric for flags, especially for indoor displays by the richest citizens who wanted to add dimension and bright colors like “wall paper.” The silk surface was also prepared by smoothing the fabric onto a frame. A thin gesso mixed with rabbit skin glue was more carefully, more thinly applied to both sides of silk fabrics. Many more colorants, especially dyes, were available for silks, which were painted and/or block printed.
A Chinese technique for painting on lightly gessoed silk included adding an opaque white paint layer to the reverse side of the painting. The gesso seeped through the fabric to create a more translucent white surface on the front side in areas reserved for faces and hands. The paintings were usually lightly colored with water media.
Captions:
“Banners” by Steve Cady
V & A Museum/Banner, tenth century
Heidelberg University, Codex Manesse
Banner, mid-nineteenth century, England, appliqué and embroidery of silk and metallic threads on damask Cooper Hewitt Museum
“Interior of Saint Peter’s, Rome” by Giovanni Paolo Panini
Banners of mid-sixteenth century Knights of the Order of the Garter
Silk stretcher
Oil/varnishes in painting studio
Triumph of Maxmillian 1, 1512 by Hans Burgkmair
“Art Treasures of Peking Museum” Beijing China