Re-gauges are typically performed by the bonded warehouse in which the cask lies. To perform the process, first, a sample is drawn from the cask. This sample is then analysed with a hydrometer to determine the alcoholic strength of the spirit.
This is a vital check for two reasons. Firstly, any spirit that contains less than 40% pure alcohol can not legally be sold as Whisky, which would considerably lower the casks value. This is a particular risk for older casks, due to the natural evaporation of alcohol during the maturation period. Secondly, the alcoholic strength determines how much duty will be paid when the spirit is bottled.
After the sample is taken and measured, the cask is weighed before being emptied and weighed again. This procedure helps to determine the quantity of liquid within the cask accurately.
By combining the alcoholic strength measurement with the quantity of liquid within the cask, the warehouse can then calculate the RLA figure. The RLA, or Regauged Litres of Alcohol as it’s otherwise known, is the industry-standard figure used when selling or bottling a cask of aged spirit.
For example, if the cask is holding 200 bulk litres and the ABV is 60%, then the RLA is 120 litres.