Organic Pigment Powder This shade card illustrates the shades of the pigments currently offered by us, and also provides technical data which is of importance in evaluating their performance in the various end uses. The data offered therefore is only meant to be of guidance value and the responsibility to obtain accurate information under any specific set of conditions rests with the users of these pigments.

Physical Properties

Specific Gravity
This property has been determined in an inert liquid at 20 degree C.

Oil Absorption (ml/100 g)
Acid refined linseed oil is added slowly from a burette to lOg pigment sample on a glass plate. Each addition of oil is worked into the Pigment with a knife spatula. This is continued until a just coherent paste is obtained. The quantity of oil so required for 100 g of the pigment is then calculated and given as the oil absorption value in terms of ml oil/1 00 g pigment.

pH of Aqueous Extract
This value is not mentioned separately since in most of the cases it is Practically 7.

Light Fastness

Partially covered strong and weak prints of the pigment dispersed in offset varnish on art paper are exposed side by side with Blue Wool Scale Standards in a “Xenotest” accelerated light testing apparatus. The degree of contrast between the covered and exposed parts of the print is assessed by comparison with the standards and the rating are given on a 1 to 8 scale as follows: 8. Outstanding       1. Very low.

Heat Resistance

A stoving paint of the pigment is prepared in a non-yellowing medium and applied on a tin panel. The temperature up to which there is only a negligible change in the shade of the colour after stoving for 30 minutes is noted and this represents the heat resistance figure included in this shade card. In case where pigment are used in rubber, the heat resistance in pigmented rubber has been indicated.

Fastness to Solvents and Chemicals

In the case of water, soda ash and hydrochloric acid, 0.5g pigment is mixed with 10ml of each of these liquids, heated on a boiling water bath for 10 minutes cooled and filtrate. The filtrate is assessed for colouration, where finely suspended pigment is present in the filtrate, the suspension is spotted on a filter paper and colour of the halo is assessed. In the case of solvents, 0.5g pigments is folded in a filter paper, sealed at the open end and suspended in 20cc of the solvent contained in stoppered test-tube at room temperature for 24 hours. The paper bag is then removed and the degree of staining of the solvent noted. The rating in both cases are given on a 1 to 5 scale as follows:
5. Pigment stains very extensively       1. Pigment does not stain