ACID FREE.
A paper product having a pH level of 7 or above.

ACIDIC.
In paper, an unstable state whereby the molecular structure of the paper breaks down, causing discoloration and weakening of the sheet.

ACRYLIC.
Refers to a class of synthetic polymeric resins used extensively in emulsion paints, varnishes and adhesive formulations. In sheet form the acrylic resins bear trade names such as Plexiglas, Lucite and Perspex.

Aertsen, Pieter (b. 1508-09, Amsterdam, d. 1575, Amsterdam). Netherlandish painter, active in his native Amsterdam and in Antwerp. A pioneer of still life and genre painting, he is best known for scenes that at first glance look like pure examples of these types, but which in fact have a religious scene incorporated in them (Butcher's Stall with the Flight into Egypt, University of Uppsala, 1551). His depictions of food, flowers, and everyday objects make him important in the development of still-life painting. Aertsen was the head of a long dynasty of painters, of whom the most talented was his nephew and pupil Joachim Bueckelaer.

Nicknamed Lange Pier (Peter the Long), born in Amsterdam, he became a citizen of Antwerp in 1542 where he resided until around 1556. Hosted initially by Jan Mandyn, a gifted follower of Hieronymus Bosch, Pieter Aertsen links the Dutch and the Flemish schools. His sons, Pieter Pietersz and Aert Pieterz, also became painters. Aertsen also trained his nephew Joachim Beuckelaer.

During his first years in Antwerp he was mainly commissioned to make altarpieces for Dutch churches. Before long he also started to paint scenes from peasant life and he gained a reputation for his paintings of market scenes and "kitchen" tableaux, which contained an abundance of fruit, fish, poultry, cheese, bread and much more.

Renowned today as the painter of "kitchens" (Christ with Maria and Martha), featuring an opulent and familiar realism, he is in fact a varied and ambitious painter, tackling both religious compositions, genre scenes and portrait: his career can be traced between 1543 and 1571 with a series of signed and dated artworks. Today he is considered as important as Bruegel among 16th century painting: a powerful and monumental artist, using splendid and frank tones, announcing the Flemish still-life developments with such realism and surcharge of details.

His compositions packed at the front with vegetables reflect a mannerist pathos specific to the 16th century; however if religious figuration is often relegated in the background in a subordinated position (a scheme that will later have much success, among his younger cousin and pupil Beuckelaer for instance, who took over this style of painting and developed it further), the religious painter should not be ignored, with such massive formats and powerful ambitions. He was tormented by iconoclasts and practiced a heroic and dignified style, close to and competing with Floris.



AGING.
The continuous action of atmospheric components- oxygen, moisture, as well as light, temperature - on materials and structures, leading to deterioration. Natural aging deterioration may also be caused by incompatible components reacting slowly within the structure.

AIR-BRUSH (Aerograph).
A small air-gun capable of spraying paint, ink, varnish or ground in a stream of fine droplets. It can be used in lithography and aquatint, for the application of a flat tint, and on drawings which are to be photographed in the half-tone technique.

ALKALINE BUFFER.
An additive used in paper-making processes and conservation treatments that will raise the pH level.

ALUMINUM.
This metal can be used in printmaking either as a plate, or as a support for an impression to be made upon. In the former case, it can be (a) engraved with the burin, (b) etched with mercuric bichloride, or (c) prepared lithographically. Impressions can be made directly onto the metal, in particular with the screenprinting technique.

Altdorfer, Albrecht (b. c.1480, Regensburg, d. 1538, Regensburg). German painter, engraver, architect and graphic artist working in Regensburg, of which town he was a citizen from 1505 onwards, the leading artist of the so-called Danube School of German painting. His most outstanding works are biblical and historical subjects set against highly imaginative and atmospheric landscape backgrounds.

The exact date and place of Albrecht Altdorfer's birth are unknown, although he was associated with the Bavarian city of Regensburg for almost all of his life. He is first documented there in 1505 when he acquired citizenship rights and was called a "painter from Amberg", a small town north of Regensburg. Since one could become a citizen in Regensburg at age sixteen, it is possible for Altdorfer to have been born as late as 1488, although an earlier date, circa 1480, seems more likely. Altdorfer became a citizen of Regensburg in 1505 and bought a house there in 1513, another in 1518 and a third in 1532; he also owned several vineyards. From 1517 he held seats on the outer and inner councils of Regensburg and represented the city on important official business. A portrait of Altdorfer is found in an illumination in the Freiheitenbuch (1536; Regensburg, Stadtmus.) by Hans Müelich, which represents him in minute profile among Regensburg's city councillors.

On the first of January, 1513, Altdorfer bought a house in Regensburg, and it was around this time that he began working for Maximilian I. He participated in group projects such as the marginal drawings in Maximilian's Prayer Book (kept in Besançon, France), the woodcuts of the Triumphal Portal, both c. 1515, and the woodcuts of the Triumphal Procession, c. 1517/1518. The artists and his shop also produced a series of illuminations depicting the victorious battles of Maximilian.

Yet in spite of these varied influences Altdorfer's style always remained personal. Most of his paintings are religious works, but he was one of the first artists to show an interest in landscape as an independent genre during the third decade of his work, maybe as a reaction to the altar of St. Florian which included large human beings. Two pure landscape paintings (without any figures) by him are known (National Gallery, London, and Alte Pinakothek, Munich), along with 9 etchings and 2 aquarelles.

On 12 February 1538 Albrecht Altdorfer died in Regensburg after making his last will and testament. The inventory of his estate, which ran to twenty pages, indicated that he was one of Regensburg's more prosperous citizens. Except for the will he dictated on the day of his death, there are no surviving papers or letters by him; nor are there contemporary writings about him.

The corpus of Altdorfer's surviving work comprises c. 55 panels, 120 drawings, 125 woodcuts, 78 engravings, 36 etchings, 24 paintings on parchment and fragments from a mural for the bathhouse of the Kaiserhof in Regensburg. This production extends at least over the period 1504-37. Most of the early works are dated: engravings 1506-11, woodcuts 1511-13; and although after 1513 Altdorfer ceased dating his prints, most, it would seem, and most of the surviving drawings, were executed by 1522. Therefore, with the notable exception of the Battle of Alexander at Issus (1529; Munich, Alte Pinakothek), the works on which his reputation rests derive predominantly from a concentrated period of activity, 1506-22.

ARCHIVAL.
An archival material should have a neutral or slightly alkaline pH; it should also have good aging properties.

ARTIST'S PROOF. (see proof)

AQUATINT. ( See printmaking techniques)
A process of intaglio engraving on metal.