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While savouring a craft cocktail at a bar, the rod or block shaped ice is a defining feature of how drinks can be made to appeal visually even before a sip has been taken. Their clear, shiny appearance with a pristine centre along with their capacity to dilute slowly makes them an interesting element – unlike the hazy white centred cubes one freezes at home. What is essentially comprised of hacking the freezing process and controlling the pace of water turning solid, clear ice is not simply an aesthetic addition to home bars but also melts evenly and slowly in drinks or if used for shaved ice.
What Makes Ice Cloudy
For most daily kitchen uses, cloudy ice cubes do just fine but has plenty to do with how water freezes on a microscopic level. When water hits the 0°C mark, the crystal formation is kickstarted by a tiny, imperfect nucleus – which ranges from a speck of dust to even the movement caused by closing the door of the freezer. In typical cube trays, ice begins to form inward in all directions while simultaneously trapping surrounding gases, air bubbles and even dissolved minerals. On coming in contact with light when unmoulded, these trapped particles provide homemade ice their cloudy effect and a dense core – irrespective of whether the mould is replaced with fancier options or even boiled or distilled water.
Understanding Freezing
The essence of achieving clear ice cubes boils down (pun intended) to a key principle – understanding the difference between directional freezing and slow freezing. With the former, the idea is to let water freeze from a singular direction as opposed to all directions. This method allows the impurities trapped within the water to be pushed downward instead of being trapped in the core – ideally replicable using an insulated container or small bottle. Insulation helps slow down freezing on the sides and the bottom, only enabling ice formation to begin when low temperatures reach the top and proceed in a downward direction.
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The controlled freezing environment provides a temperature gradient – one where the top surface is colder than the sides which have been insulated and allowing the freezing to spread slowly and spread down gradually, pushing air bubbles to the bottom most layer. As important and crucial this is, the duration which water takes to freeze also has a significant role to play in its clarity. On an average, clear ice takes anywhere between 24-48 hours to form depending on the manner in which it has been frozen and size of the cubes. Using an insulated container wraps the water in ‘warmth’ on all sides but the top, which slows down freezing time and enables the formation of larger, orderly crystals with minimal impurity trapping.
Making Clear Ice At Home
While multiple options for insulated ice moulds are available for purchase, it is always advisable to invest in clear ice moulds designed specifically to freeze from the top down. Opt for various shapes and sizes to have a variety – depending on the purpose for which they are being used. An insulated thermos also does the trick – however with a bit of extraction challenge since the ice becomes tough to remove, once frozen. However, the two-tier, stainless steel filter coffee device with its stackable compartments is not only easy to disassemble and unmould, but also provides exact conditions required for ice to freeze into a clear block. Fill up both containers with water and place it inside an insulated thermos for anywhere between 36-48 hours, ensuring that there is no room for the contraption to be disturbed by movement or vibration.
