To make single malt (which is the product of one single distillery) you need malted barley, water, and yeast.
The barley is mashed with hot water, producing a sugary liquid called wort, which is then fermented with yeast into a strong beer called wash (around 9-10% alcohol by volume usually!), the wash is then distilled in copper stills – normally twice – firstly in wash stills, this will increase the percentage of alcohol to around 20-25%, then again in spirit stills, the alcohol content here will be much higher. Distilleries portion off what is known as the ‘middle cut’ – usually 64%-74% alcohol by volume.
This ‘middle cut’ can then be diluted with water (optional) and filled into an oak cask to mature. After 3 years of maturation in a bonded warehouse, legally this can now be called Single Malt Scotch Whisky. Many casks can be married together to create a more harmonious tasting liquid but so long as they were distilled at the same distillery it remains a single malt.
If we take casks of single malt from multiple distilleries and blend them together, we get something like Naked Malt – crafted from some of the finest single malts from across Scotland. Blending only single malts together gives you blended malt.