This International Standard specifies a method of determining, using an ashing procedure, the amount of bale coating present on the outside wrapper sheets of bales of natural rubber. It also specifies a method for determining, by a brushing or scraping procedure, the amount of bale coating on the outside wrapper sheets of all grades of smoked sheet rubbers only. NOTES 1 The brushing or scraping procedure, while much faster, is not suitable for use on crepe rubbers because coating dust penetrates in through holes in the outside wrapper sheet and is difficult to remove from between wrapper sheets. This necessitates the use of the ashing procedure on crepe rubbers. 2 The ashing procedure is not suitable for coating materials which are affected by the ashing procedure. In particular, coatings containing carbonates or organic matter can give very low results.