Page 9 - George O'Hanlon

Making stack process flake white (or lead white made according to the "old Dutch method") is time-consuming and prone to variations in the resulting pigment. These variations are not surprising and were well known from literature and historical documents of the process by manufacturers of lead white. It was a major issue of the process that manufacturers dealt with in various ways. This article describes the reasons for the variations and how these may be useful to artists.

Natural iron oxide pigments, or iron oxide earth pigments collectively referred to as iron oxides, comprise both oxides and oxide hydroxides of iron. Hematite (α-Fe2O₃) is the most common iron oxide in red earth pigments, and the iron oxide hydroxide goethite (α-FeOOH) is the most frequently found iron compound in yellow earth pigments. Umbers are brown earth pigments containing both oxides of iron and manganese.

Oil paint is a slow-drying paint consisting of pigment particles suspended in a drying oil, commonly linseed oil. The viscosity of the paint may be modified by adding a solvent, such as turpentine or mineral spirits (white spirits), and varnish may be added to increase the glossiness of the dried film. In this article, you will find complete descriptions of oil painting mediums or additives (or, as we prefer to call them, "amendments") made by Natural Pigments. These amendments are designed to alter the consistency of oil paint in novel ways, different from the varnishes introduced into everyday use during the eighteenth and nineteenth centuries.

Studies of the reaction of painting supports, oils, and pigments to changes in the environment during the past hundred years make it possible to understand the behavior of paintings. Modern commercial oil paints present new issues to conservators as they observe defects in paint films caused by new pigments and additives used in their formulations.

Fluorescence is a phenomenon where a substance absorbs light at a specific wavelength and then re-emits the light at a longer wavelength. This re-emitted light is known as fluorescence. Fluorescent pigments are substances that can fluoresce and are widely used in various applications, such as in art, science, and industry.

Fluorescence occurs when a molecule, called a fluorophore, absorbs a photon of light at a specific wavelength and then re-emits the light at a longer wavelength. This process is known as fluorescence and is caused by the movement of electrons within the fluorophore.

Fluorescent pigments are made up of a variety of different compounds, such as fluorescent dyes, fluorescent inks, and fluorescent plastics. These pigments are used in many applications, including art, science, and industry.

There are several types of fluorescent pigments, each with its unique properties. One type of fluorescent pigment is called a “dayglow” pigment, which is highly fluorescent and visible...

Lead sulfate (British spelling, sulphate) formed the basis of several white pigments that were made on a large scale in the 19th and 20th centuries and sold under a variety of names, such as "Patent White Lead," "Non-poisonous White Lead," "Sublimed White Lead," etc. Some of these pigments did not consist entirely of lead sulfate but contained other minerals, such as zinc oxide, barite (barium sulfate), magnesia (magnesium carbonate), etc., in varying quantities.

Support Induced Discoloration (SID) occurs when paint changes color due to pulling up water-soluble substances from the substrate. As the paint dries, these particles remain in the paint, discoloring it. Read how to avoid the discoloration of paint on wood supports.

Tempera is a method of painting with pigments dispersed in a binder that is miscible with water such as egg yolk, casein, gum, or hide glue. This article examines the type of supports used today for tempera and the best practice of preparing them for tempera paint using a new ground, Tempera Ground, made by Natural Pigments.

It is an old saying that rules are meant to be broken. No one did this more successfully than Rembrandt. For instance, the rich red in the tablecloth in the Syndics is obtained by glazing a translucent red over brown instead of a brighter red. Rules are meant to be broken, but it is necessary to know them first. Read more about these painting rules.

For over a hundred years, most of the causes of cracking have been explored: humidity and temperature, expansion and contraction, stress, and paint embrittlement. The symptoms were obvious—cracking and paint loss—but the causes were not clearly understood. In 1982, Marion Mecklenburg and other scientists at the Smithsonian Institute reported the first systematic explanation of painting mechanics, especially that of canvas paintings.