In the glass on the left the reduced ABV (below 44%) has caused the esters with a longer molecular chain length such as lauric, palmitic and palmitoleic acid to react with the acid fats and cause a hazing of the spirit. The below video by the fantasic Ralfy (if you’ve not already I highly recommend subscribing to his YouTube Channel) explains the process and the consequences of chill filtration and why it might work for blends but is tragic for malts!
If you’re anything like I am you’ve most probably spent a fair amount of time pouring over your whisky labels trying to learn more about the spirit in your glass, you might have also noticed that the words non chill-filtered are generally accompanied by a higher ABV but had no idea why. You might have noticed that they’re also generally speaking better whiskies, a fantastic example would be the Glenfiddich 15 Distillery Edition I’ve recently reviewed. Put in simple terms chill filtration is a cosmectic process whereby tasty fatty acids left behind by the grain are removed to give a clearer looking spirit at lower ABV. As these acids are soluble in high (44%+) alcohol you would only notice the hazing if the spirit was bottled arounnd 40% ABV or if you add water: