The addition of the mentioned ingredient is intended to facilitate crumbing. This part of standard aids the estimation of the amount of oil remaining in the rubber. Triglyceride of ricinoleic acid is the principal constituent of castor oil (80...85 %). Method applicable to all grades of natural rubber. Lower limit of detection approx. 0.05 % of castor oil glycerides. - Part 2 of this standard refers to the total ricinoleic acid content.