Rev. Rul. 66-229

The Internal Revenue Service has been asked whether copper sulfate may be used as a clarifying agent in the production of grape wine.

The use of copper sulfate as a clarifying agent to clarify and stabilize grape wine is considered as being consistent with good commercial practice. However, the addition of copper sulfate may not exceed 0.5 ppm with a residual level not in excess of 0.2 ppm.

Winemakers desiring to use this clarifying agent in the treatment of wine may obtain approval of the Assistant Regional Commissioner, Alcohol and Tobacco Tax, by filing a notice pursuant to the provisions of 26 CFR 240.1052.