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Oil Absorption of Pigments

IP.com Disclosure Number: IPCOM000073640D
Original Publication Date: 1971-Jan-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Williams, CL: AUTHOR

Abstract

Pigments incorporated into coating compositions are commonly characterized by oil absorption tests. In this type of test, a measured amount of pigment is mixed into a paste with linseed oil. The quantity of oil required to reach a reproducible end point, normally the formation of a paste or of a single lump of pigment, is related to the size, surface area, and surface roughness of the particles. The smaller or rougher the particles, the more oil is required to reach the end point. A widely accepted method of testing oil absorption of pigments is by the Gardner-Coleman method, as described under the American Society for Testing and Materials designation: D 1483-60. In the Gardner-Coleman method, as well as in most other reported methods of testing oil absorption, mixing of pigment and oil is done manually.

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Oil Absorption of Pigments

Pigments incorporated into coating compositions are commonly characterized by oil absorption tests. In this type of test, a measured amount of pigment is mixed into a paste with linseed oil. The quantity of oil required to reach a reproducible end point, normally the formation of a paste or of a single lump of pigment, is related to the size, surface area, and surface roughness of the particles. The smaller or rougher the particles, the more oil is required to reach the end point. A widely accepted method of testing oil absorption of pigments is by the Gardner-Coleman method, as described under the American Society for Testing and Materials designation: D 1483-60. In the Gardner- Coleman method, as well as in most other reported methods of testing oil absorption, mixing of pigment and oil is done manually. Therefore, oil absorption determined is dependent not only upon the characteristics of the pigment, but, to some extent, upon the technique of the individual performing the test. The ASTM reports that repeatability of the Gardner-Coleman oil absorption test by the same operator is +/- 5% while reproducibility of the Gardner-Coleman technique by different operators agrees within +/- 10%. Increased repeatability and reproducibility is obtained utilizing the following technique.

Initially, oil absorption of the pigment to be tested is roughly determined. In subsequent tests, a measured amount of pigment, for example 20 grams, is placed into a closable container. A fixed increment of oil, for example, 3 to 7 ml., is added to...