Visible faults

Faults in a wine’s appearance are generally either hazes, clouds, or precipitates in the bottle. stabilization is designed to avoid all these hazards. (In the past, bacteria sometimes affected a wine’s viscosity, but this problem is rare today.) Haze and cloud in bottled wines can have a variety of causes, of which the most common today is the growth of the micro-organisms yeast or bacteria. Mycoderma is a yeast-related fault which forms a film on the wine’s surface (and so may be visible to winemakers, if not to wine consumers). Clouds from heat-unstable proteins and from heavy-metal contamination do occur but they are much less frequent than they were in the era of copper and brass pipes and taps.