Tempering of Clear Craft Ice

Tempering of Ice

With a stash of clear craft ice built up, placed in storage containers and stored in a freezer, cubes are almost ready for future use. In a hurry to use clear craft cubes, the ice is placed in a glass and liquid is poured over it. Suddenly a large crack appears in the ice. The beautiful craft ice cube now has fissures throughout the cube.  What happened and how can this be fixed? 

Ice has a very defined structure in the solid state. It can be brittle, very similar to glass.  Brittle materials can be extremely sensitive to large temperature differentials between the core (inside) and surface (outside).  A classic example of this can be observed when a hot glass cup is placed under cold water, and it breaks or shatters.  This is known as thermal fracturing and is exactly what has happened to the once clear ice cube. 

Tempered Ice

Tempering Clear Craft Ice  Tempering clear craft ice

Non-Tempered Ice

  Tempering Clear Craft Ice
The high temperature differential between the ice cube and the liquid being added creates thermal stress. The higher the temperature differential, the higher the likelihood and severity of cracking.
Experiments were conducted to illustrate best practices for tempering.  Here, a cube of varying temperature was placed in a glass then liquid of varying temperature was poured over  it.  The severity of cracking was then observed.
  

Experiment 

Liquid Temperature 

Ice Temperature 

Results 

1 

Room Temperature (75°F/24°C) 

-20°C (Right out of freezer) 

Cracked badly, no clarity 

2 

5°C Refrigerated Water 

-20°C (Right out of freezer) 

Edges cracked 

3 

Room Temperature (75°F/24°C) 

0°C 

No cracking 

4 

5°C Refrigerated Water 

0°C 

No Cracking 

 

From the experiments above, the combination of cooling the liquid and warming the ice (experiment 4) is the best method to maintain the integrity of the cube clarity and slower melt time.  Do not forget, with a higher temperature differential between the cube and liquid, more cracking and dilution will be experienced!  

To help determine the right time duration for cube tempering before pouring a drink, Klaris has you covered with more data.  Testing showed the following results: 

Time (min) 

Initial Ice Temp 

Initial Water Temp 

Results 

0 

-20°C (Right from freezer) 

Room Temp (75°F/24°C) 

Cracking 

1 

-20°C (Right from freezer) 

Room Temp (75°F/24°C) 

Cracking 

2 

-20°C (Right from freezer) 

Room Temp (75°F/24°C) 

Slight Cracking 

3 

-20°C (Right from freezer) 

Room Temp (75°F/24°C) 

No Cracking 

4 

-20°C (Right from freezer) 

Room Temp (75°F/24°C) 

No Cracking 

Best practices recommended by Klaris

  • For just a drink or two, remove the cube(s) from the freezer and let each cube sit (temper) in a glass for 3-4 minutes before pouring the drink. 
  • For larger parties with multiple drinks served throughout the course of a night, place multiple cubes in the refrigerator 1 to 2 hours before first serving.  Refrigerated cubes will lose little to no shape (a testament to slow melting) over the course of 4 hours and will be ready to serve directly out of the fridge! Cheers to maintaining clear ice! 
Back to blog