Nelson-Denny Practice Test 10

Painting into Plaster

¹For the great wall paintings of Renaissance Italy, artists often relied on a technique known as buon fresco, or "true fresco." The painter applied pigments mixed only with water to a layer of freshly spread lime plaster. As the plaster dried, the lime reacted with carbon dioxide in the air to form calcium carbonate, locking the pigment particles into a thin crystalline skin. The color did not merely sit on the wall; it became part of the wall.

²This permanence came at a price. Because the plaster stayed workable for only part of a day, a painter could prepare only as much wall as could be finished before it set. Each such section is called a giornata, from the Italian word for "day," and on many frescoes the faint seams between sections can still be traced, revealing the order in which the work was done. Mistakes were hard to correct: an error usually meant chipping away the plaster and starting that section again.

³Some colors posed a further problem. Certain pigments, including some blues and greens, reacted badly with the alkaline lime, so artists added them afterward on the dry plaster, bound with glue or egg. This method, called fresco secco, allowed more time and a wider range of colors, but the paint lay only on the surface. Centuries later, it is often these secco passages that have flaked away, leaving bare plaster where a sky or a robe once glowed.

⁴Fresco thus rewarded planning over improvisation. Before the plaster was spread, a painter had to know exactly what that day's section would contain. This is one reason full-size preparatory drawings, transferred onto the wall before painting, became so important to the practice.