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Natural Pigments Aluminum Stearate

The minimum order amount for this product line is $30.00
Natural Pigments Aluminum Stearate 500 g Natural Pigments Aluminum Stearate 1 kg
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Product description

Aluminum stearate (aluminum di-stearate) is a white, wax-like powder (metallic soap) that dissolves in mineral spirits or hot oil. A small amount (2% or less) added to oil paint imparts a short, buttery consistency. It eliminates the separation of pigment and oil, thickens varnishes considerably. A concentrate of aluminum stearate and linseed oil can be prepared ahead of time and added to the paint whenever needed.

Aluminum stearate is made via the precipitation process using high quality stearic acid and exhibits the following properties: Good gelling and thickening action, excellent water repellency, transparency and a synergistic effect with zinc stearate or calcium stearate.

The effects of metal soaps on pigments have been extensively studied. Aluminum stearate was found to coat the surface of pigment particles and helped prevent settling as well as reducing the amount of oil needed to wet the pigment. The amount of aluminum stearate needed to coat pigments varied on a weight basis, but a solution of 2% by weight (weight of aluminum stearate/weight of oil) of aluminum stearate was more effective than 0.5% or 4% solutions in altering pigment surfaces (Gardner 1930). The soaps coat the surface of the pigments and by steric effects keep the particles from aggregating (Pilpel 1963), which helps to keep the particles in suspension.

With increasing amounts of aluminum stearate the oil pigment mixture becomes viscous, and by using an appropriate amount of aluminum stearate the paint can gel at a lower pigment concentration (Mayer 1965). This can be used to create a "cheaper" paint since a smaller amount of a costly pigment needs to be used. A significant advantage of using stearates is that the oil and pigment do not separate greatly over long periods of time in the paint tube. Manufacturers of artists' paints often use aluminum stearate in their formulations without listing it as a component on the product label.

Aluminum stearate exhibits relatively high solubility in hydrocarbon solvents (such as mineral spirits) when compared to other metallic stearates. It is insoluble in water, alcohol and ether; but is readily soluble in benzene, acids and common solvents when hot.

Aluminum stearate has long storage life if stored in cool and dry location.

How to Use
Aluminum stearate dissolves in vegetable oils on heating and if a high enough concentration of the soap is used, gelling occurs on cooling. In the usual practice of making paints, the aluminum stearate is ground with the pigment before the bulk of the oil is added. To prepare a concentrated solution (10%), add 200 grams of aluminum stearate (nearly fills a one liter measuring cup without compacting) to one liter of linseed oil. Heat the oil to about 150� C. and gradually slowly adding the white powder to the hot oil with stirring. Add one part of this solution to four parts of oil by weight of oil before adding to pigments and grinding.

Gardner, H. A., (1930) Physical and Chemical Examination of Paints, Varnishes, Lacquers, and Colors, 5th Edition, pp. 884-896.

Mayer, R., (1965) The Artist's Handbook of Materials and Techniques, Revised Edition, The Viking Press, New York, pp. 150-153.

Pilpel, N., (1963) Properties of Organic Solutions of Heavy Metal Soaps, Chemical Reviews, 63, pp. 221-234.

Chemical Name Aluminum Di-Stearate
Chemical Formula C36H71AlO5
CAS 300-92-5
Chemical Analysis
Aluminum 4.7-5.3%
Free Fatty Acids 4.0-7.0%
Typical Physical Properties
Retained on 200 Mesh Screen 10% maximum
Moisture Loss @ 110� C. 1% maximum
Bulk Density 220-290 g/L
Melting Point 150-165� C.
Specific Gravity 1.07

Natural Pigments

Natural Pigments is a limited liability company based in Willits, California. We manufacture and distribute rare and hard-to-find materials for fine artists and decorators. We specialize in supplying artists' materials that were used in historical painting since pre-historic times up to and including the nineteenth century.

We constantly search for materials and products of the finest quality so that we can bring them direct to you from the source. To do so, we travel the world to find materials specifically for use by professional artists and decorators. We obtain minerals from mines in Afghanistan, Chile, Russia, Ukraine and Uzbekistan, to name a few places, processing these into natural pigments. We purchase resins, gums and plants from India, Kenya and Malaysia to make natural varnishes and painting mediums.

Our mission is to provide the largest variety of natural pigments, paints and other professional artists' supplies, enabling us to bring you a selection that makes shopping for rare and hard-to-find art materials easy. Our objective is to promote the education and use of these materials among artists by providing detailed information for their employment in encaustic, fresco, oil, watercolor and tempera painting.
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This product is shipped from our warehouse in Gretna, NE, USA.
This product is brand new and includes the manufacturer's warranty, so you can buy with confidence.
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Product line (2 items)

SKU Thumbnail Product name List price Price Quantity Extended price
NAP-510-15ALD50 US$ 19.69
NAP-510-15ALD10 US$ 35.61

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