egyptian blue

EGYPTIAN BLUE.

description of Egyptian blue:

Very stable synthetical pigment of varying blue colour. It is a copper calcium silicate that was the first synthetic pigment and the most extensively used from the early dynasties in Egypt until the end of the Roman period in Europe. Many specimens, well over 3000 years old, appear to be little changed by the time. The new life of Egyptian blue.

Egyptian blue could find use in the modern era in applications such as biomedical analysis, telecommunications, and lasers, according to a new report (2009). A quantitative study of the pigment luminescence properties assesses its quantum efficiency and lifetime. It was found that Egyptian blue has an exceptional high luminescence quantum yield for a molecular-level infrared emitter. Egyptian blue's long luminescence lifetime and intense IT emission make it a promising candidate for use in biomedical application, for example, because IR photons can deeply penetrate human tissue and the pigment's emission at 910 nm minimizes light absorption by tissues. Furthermore, the pigment is extremely stable, exhibiting bright luminescence even after millennia. Ancient Egyptians may not have gained eternal life but one of their most frequently used pigments may now have a future in a variety of high-tech applications.

Pigments in Pastels.

What is Pastel?

Pastels are usually in stick form, similar to chalk. A pastel stick consists of pure powdered pigment and an inert binder, such as gum arabic, gum tragacanth, or methyl cellulose. Pastels have a higher pigment concentration than any other artist medium (hence the rich, luminous colors that pastels can achieve). The powdered pigments used in pastels are similar to those found in oil paints.

how do you make this?

(A) Place powdered gum tragacanth into a glass jar, add water and mix to dissolve. The ratio is typically 1 part gum tragacanth to 30 parts water. Close the jar and refrigerate it for at least 48 hours. The mixture will become a gelatinous solution. (B) Place powdered pigment on a glass palette. Make a hole in the middle of the pile of pigment. Pour a very small amount of the gum tragacanth solution into the center of the pigment. Using a palette knife, mix the pigment and the gum tragacanth solution. (C) If necessary, add more gum solution. Mix thoroughly until the mixture reaches a doughy consistency. (D) To make a lighter shade of blue, add a pile of white pigment to the remaining blue pastel. Add a small amount of gum tragacanth, and repeat the mixing process. (E) Mold the doughy pastel into a stick form. Place the pastel on absorbent paper, such as a paper towel. Allow the pastel to dry (typically 24-48 hours). You can create your pastels in any shape that you want, depending on what you might want to use it for. (F) The dried pastels and the marks that they make on abrasive paper.