Fining agents can be used singly or in combination. The correct fining agent to use depends on the wine’s chemical composition, and the nature of particles in suspension. It is best to carry out comparative trials of different agents at different doses, using small volumes of wine. This can be a two-stage process:

• Trial 1: using a range of fining agents at ‘average’ doses to determine the most appropriate one.
• Trial 2: using a range of doses of the most appropriate fining agent. The selected fining and rate should be the lowest rate to give the best quality of wine aroma and flavour, clarity, rapid sedimentation and leave the least lees volume.

Once the required level is determined, the fining procedure can be carried out. It is vital that fining agents are mixed thoroughly in the wine as soon as they are added. They are then left to settle (days/weeks) before being racked and, if required, filtered.

Fining agents are sometimes added to musts before fermentation, but usually they take too long to settle to be of much use. Most fining agents are added after the end of fermentation and after one or two rackings, when the wine is quite clear and relatively free of carbon dioxide.

The following calculation can be used to help construct the fining trials.