Why is this important? Per 27 CFR 24, wineries are allowed to add up to 6.0 mg/L (ppm) of copper to a wine while in production. In a TTB regulation update, the residual copper concentration must “not exceed” 1.0 mg/L (ppm). However, the DG Winemaking recommends keeping residual copper concentrations below 0.5 mg/L […]