Cask strength whiskies are often regarded as whisky in its purest form.
When it is decided that the cask is ready for bottling, the whisky is then cut with local spring water and then blended with other whiskies to make the finished style.
Cask strength whiskies are simply bottled directly from the cask at the natural strength from the barrel, often in excess of 55% abv. It is up to the person drinking their whisky to 'cut' it with mineral water, to get their their preferred strength.
Cask strength whiskies are regarded as a true expression of how a cask can mature at a distillery. They are unique expressions of the distillery's style of whisky and no two casks will ever taste the same.
Most whiskies, and other spirits, are chilfiltered to stabalise the liquid that is being bottled. This will stop it from clouding if the bottle gets cold. Not a problem to the whisky as its will clear as the bottle warms up, but it often causes complaints from customers who do not appreciate that this is a natural phenomenon that occurs.
For big brand owners it is important that this does not happen, as customers often feel it is a fault in the spirit, hence they filter and cold stabalise the product. However, some master distillers feel that chilfiltration and cold stabalisation removes some of the essential oils and character of the spirit which ultimately detracts from the final tasting experience for the customer.
Often it is assumed that the whisky in the glass is its natural colour. Colour in a whisky comes from the cask, a sherry cask will give the spirit a deep golden colour, whereas a bourbon cask will make the spirit light, almost a straw yellow colour. However, there will always be variation in the colour that comes from different casks. Again, this is natural.
Some brand owners will add an addition of caramel to be used as a colouring agent to ensure that all the bottles are consistent. Is this important? I suppose it is if you are a brand embassador.
From an interest point of view, look out for labels that say that the spirit Natural Colour, you will be buying a whisky that the master distller is proud of.
A Quick History of Whisky
Types of Malts
Now Whisky is Made
Influences on Whisky Flavour and Aroma
Whisky Style Chart