The scribe often left instructions for the illuminator. Within
or near the space left out for splendid initials, often
a tiny letter indicated what letter should be included
there. Occasionally, as in 13th century Cistercian manuscripts
that used a single color for initials, a spot of paint was included
to indicate the color of the initial. The names of colors were
sometimes inscribed on the margin or within the design itself.
The illuminator
began by laying out the design in leadpoint or graphite. When
the underdrawing was completed, it was reinforced with ink.
Pigments
would be mixed with some sort of binding medium that kept the
pigment particles together. Until the fourteenth century the most
widely used binding medium was glair. Glair was an optimal medium
for miniature painting, free-flowing and easily applicable, but
was fairly difficult to prepare well. Besides, it reduced the
natural saturation of colors, and was therefore sometimes varnished
with honey after drying. After the fourteenth century glair was
replaced with gum arabic (the gum of a domestic tree). Its advantages
included the fact that it could be more thinly applied, thus the
resulting colors were more transparent and saturated. The two
types of binding media were sometimes used together or occasionally
mixed with further types of binding media such as egg yolk, sugar,
or ear wax.
The
technique, which both the glair and gum arabic mediums encouraged,
was similar to tempera painting, that is, slow-paced, careful
work with tiny, meticulous brushstrokes, creating clearly defined
forms and homogenous areas of color. The painting of the illustrations
started with application of the basic colors in numerous layers
of washes, and with outlining the original lines of the sketch.
Then darker tones were added, followed by the addition of the
highlighting to add a sense of depth. The use of very small brushes
and the easily controllable, free-flowing medium was a prerequisite
for the execution of the minute pictures that were usually rendered
in great detail. When the book was still in separate leaves, the
artist could work on a number of pages at the same time, and mix
colors for use on more than one page.