Burnt Umber Research Articles

Lightfastness of pigmented handmade papers

AbstractArtists are making pigmented handmade papers in increasing numbers to be certain that the color of the paper is lightfast. The lightfastness of handmade papers colored with commonly used pigments was tested. Three methods were used: (1) exposure to a measured 1260 MJ/m2 outdoors to the sun under glass; (2) exposure in the laboratory to daylight fluorescent lamps; and (3) exposure in a window monitored by Blue Wools. Burnt umber and the yellow and red iron oxides were lightfast as expected. Excellent, or sufficiently lightfast, were Pigment Yellow 65 and the lightfast form of Pigment Yellow 74, the phthalocyanine blue and green, ultramarine blue, and the Quinacridone reds if used in sufficiem strength. If the Quinacridones were weaker they were classified as Good in lightfastness along with Pigment Yellow 97. Classified as Fair were the higher‐strength form of Pigment Yellow 74 and the naphthol red with AS‐D coupling. Unsatisfactory, or fugitive, were the lithol and toluidine reds, weaker use of the higher‐strength form of Pigment Yellow 74, and an unidentified organic yellow pigment.

Dentures to harmonize with heavily pigmented tissues

For those dental patients whose oral tissues are not a monotone pink, an acrylic resin simulating their heavily pigmented mucosa is necessary. Those dentists who serve non-Caucasians can produce a resin for these patients with acrylic powder, chalk that is burnt umber in color, and the implements normally found in the dental office. For those dental patients whose oral tissues are not a monotone pink, an acrylic resin simulating their heavily pigmented mucosa is necessary. Those dentists who serve non-Caucasians can produce a resin for these patients with acrylic powder, chalk that is burnt umber in color, and the implements normally found in the dental office.

The Russell and Abney Report on the Action of Light on Water Colours

In 1888 Russell and Abney published the results of a series of experiments on the influence of light on watercolours. Samples were exposed on Whatman Paper tomixed sunlight and daylight equivalent at least to 480 years of exposure to daylight in exhibition galleries. The following is a list of pigments in order of stability commencing with the lease stable: carmine, crimson lake, purple madder, scarlet lake, Payne's grey, naples yellow, olive green, indigo, brown madder, gamboge, Vandyke brown, brown pink, Indian yellow, cadmium yellow, Leitch's blue, violet carmine, purple carmine, sepia, aureolin, rose madder, permanent blue, Antwerp blue, madder lake, vermilion, emerald green, burnt umber. Pigments which did not show any change after exposure are the following: yellow ochre, Indian red, burnt sienna, chrome yellow, lemon yellow, raw sienna, terre verte, chromium oxide, Prussian blue, cobalt, French blue, ultramarine ash. After exposure to dry air, to wet air, to hydrogen, under vacuum, under coloured glass etc, Russell and Abney came to the following conclusions, among others, that the presence of humidity and oxygen is, in general, essential for fading. The blue and near violet end of the spectrum produce the most important changes. The article ends by giving some of the consequences of the report.

ADDITIONAL NEW RHOPALOCERA (LEPIDOPTERA)

Papilio cresphontes Cram., tr. f. forsythae new tr f.In typical Florida and southern United States examples of cresphontes, the ground color is pale yellow. In this tr. f. the ground color is a deep canary yellow, practically an orange or burnt umber, similar to Papilio rutulus ammoni Behrens which is well illustrated on pl. I of Comstock's “Butterflies of California.”

Physical and Chemical Properties of Commercial Arsenical Insecticides: I. Manganese Arsenate

The patented methods of making manganese arsenates for insecticidal use consist in treating a manganese compound, such as pyrolusite, with white arsenic (As2O3) in the presence of nitric acid as a catalyst. The manganous arsenate formed is partly converted to the trimanganoarsenate by treatment with manganese carbonate to lower the water soluble arsenic content. The brown color of the insecticide is produced by treating the mixed arsenates with lime, which decomposes some of the arsenates with the formation of calcium arsenate and hydrated oxides of manganese. Burnt umber is also generally added to cheapen the product. The chemical analysis of the commercial insecticide shows that the total arsenic content runs close to 40 per cent calculated as arsenic pent oxide As2O5; that the water soluble arsenic content ranges from 0.7 arsenic pent oxide As2O5; and that the total manganese calculated as to 1.5 per cent calculated as manganous oxide (MnO) ranges from 31.6 to 40.7 per cent. The lime content, present mostly as calcium arsenate, ranges from 15.5 to 16.4 per cent calculated as calcium oxide (CaO). The commercial manganese arsenate insecticide is a complex mixture of various arsenates of manganese, calcium arsenate, oxides of manganese and smaller quantities of aluminum, iron, silica, etc. The composition of different samples is not the same.