Generally, alcoholic flavoring material must be gauged when dumped. However, when received from a manufacturer in a closed, nonporous container such material may be gauged by using the proof shown on the container label or a related statement of proof from the manufacturer. When the proof is determined from a label or manufacturer's statement, the proprietor will test a sufficient number of samples to verify the accuracy of the proof so determined. TTB may require that alcoholic flavoring materials be gauged by the methods provided in part 30 of this chapter.