(a) Use of carbon dioxide. The addition of carbon dioxide to (and retention of carbon dioxide in) still wine and still hard cider is permitted if at the time of removal for consumption or sale, the still wine or still hard cider does not contain more than 0.392 gram of carbon dioxide per 100 milliliters of wine.

(b) Tolerance limit. A tolerance of not more than 0.009 gram per 100 milliliters to the maximum limitation of carbon dioxide in still wine and still hard cider will be allowed where the amount of carbon dioxide in excess of 0.392 gram per 100 milliliters is due to mechanical variations that cannot be completely controlled under good commercial practice. A tolerance will not be allowed where it is found by the appropriate TTB officer that the proprietor continuously or intentionally exceeds 0.392 gram of carbon dioxide per 100 milliliters of wine or where the variation results from the use of methods or equipment determined by the appropriate TTB officer to be not in accordance with good commercial practice.

(c) Penalties. Penalties are provided in 26 U.S.C. 5662 for any person who, whether by manner of packaging or advertising or by any other form of representation, misrepresents any still wine or still hard cider to be effervescent wine or a substitute for effervescent wine.

(d) Records. Records for the use of carbon dioxide in still wine must be maintained in accordance with § 24.319 of this section.