3.1 This practice may be used to determine non-protein or non-nitrogen containing organic matter in leather which is not extractable with water or hexane. Examples would be vegetable tannins and acrylic lubricants.

1.1 This practice covers the determination of the combined tannin and nonextractable organic resins and the degree of tannage of all types of vegetable-tanned leather and leather with organic retannages. This practice does not apply to wet blue.