March 7

How Long Does Ice Take to Freeze? And How to Speed it Up

Written by: Caitlin Clark

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Curious to know how long it takes for ice to fully freeze?

While timing will depend on a lot of variables, a standard freezer at standard freezers temperature usually takes 3-4 hours to freeze cubes of water. 

In this article, we'll break down exactly what variables effect freezing time and how you can use this knowledge to freeze water faster.   

It Takes ~3 hours  For a Standard ice Maker to  Freeze and  Distribute Ice

Enjoy!

Freeze Time Depends on...


Size of the Cube

Smaller cubes have a higher surface area to volume ratio, and more surface area allows heat to escape into the environment so that small cubes will freeze more quickly.

If you want faster ice, make smaller cubes. 


Receptacle Material

Some materials transfer heat better than others. Metals like aluminum or copper transfer heat away from the water.

Plastic, glass, and silicone act as insulating agents, preserving heat in the water.

If you use a plastic container, the ice will freeze faster than if you use a glass or silicone container. 


Minerals and Ions in Water

Minerals or solutes dissolved in water make it harder for water to freeze; solutes decrease the freezing point of water.

Most of us are familiar with this effect from salt scattered on winter sidewalks.

The salt doesn’t actually “melt” the ice;

instead, it dissolves into thin layers of surface melt water on the sidewalks and lowers its freezing temperature so that the weather must get even colder before the sidewalks can freeze over again. 

So, for faster freezing, use purified water. 


Altitude

Air pressure is lower at high altitudes, which slightly increases the freezing point and lowers the boiling point of liquids.

The change in freezing point at high altitude is not as dramatic as the change in boiling point, so you probably won’t notice the difference outside of a physics lab! 

So, for faster freezing, bring your freezer up to higher altitudes. 


Accompanying food in the freezer

Warm or partially frozen food in the freezer lowers the ambient air temperature, slowing the speed of heat transfer away from the water.

This delays the rate at which it freezes into ice, but it will hardly be noticeable. 

So, for faster freezing, don't add food to the freezer. 

How to Freeze Ice Faster


ice-tray

Some tricks to freeze water faster include...

1) Making smaller ice cubes

2) Freeze in a metal container

3) Making sure everything is already frozen in your freezer.

4) Use a freezer that is set at a colder temperature.

 Also, try making your cubes with hot water. That’s right! This last counterintuitive observation is called the Mpemba Effect.


The Mpemba Effect

Mpemba Effect Explained

In a 1969 paper tantalizingly titled “Cool?”, Ernesto Mpemba described a cooking class he had taken as a schoolboy in Tanzania.

While making ice cream, he observed that a hot solution froze faster than a cold solution.

Although its mechanism remains controversial, this phenomenon has been replicated over the years.

The Mpemba Effect is attributed to everything from convection currents to micro-bubbles.  


Using the Mpemba Effect to Speed Up Freeze Time

Try it yourself!  

For quick-freezing ice, place hot (above 113°F, but not boiling) water in an uncovered ice cube tray, and you’ll observe that it transforms into ice approximately 15% faster than cold water.


Techniques to speed this up even more are...

1) Use a container that has a large surface area, such as a baking dish.

2) Stir the water constantly as it cools. This prevents the formation of ice crystals at the edges, and allows the entire batch to freeze more quickly.

Best Freezer Temp to Freeze Ice Faster


temperature-reader

When it comes to freezing ice cubes as quickly as possible, the freezer temperature is an important factor to consider.

The ideal temperature for freezing ice cubes is -18 degrees Celsius (-0.4 degrees Fahrenheit).

If your freezer is set colder than this, your ice cubes will freeze slightly faster. If your freezer is set warmer than this, your ice cubes will freeze slower. 

But if you're using an ice maker, contrary to intuition, colder is not always better. If an ice maker's pipes freeze, the machine will lose air circulation, crippling its ability to produce ice.

A temperature between 0-5°F is ideal for maintaining a working ice maker while safely preserving stored food. 

How Long Does it Take to Freeze Popsicles?


popsicle

When it comes to making popsicles, there's nothing more frustrating than waiting for them to freeze solid.

Depending on the recipe and the freezer temperature, it can take anywhere from a few hours to overnight.

Technically, water freezes at a rate of approximately 3 hours per 100 cm3 (or about 3.4 fluid ounces–about the size of a child’s popsicle mold) at a typical freezer temperature of 0°F.

However, it may take popsicles double that to freeze completely solid because their freezing temperature is depressed from the addition of solutes like sugar and flavorings and because they are often insulated in thick plastic molds.  

The best freezer temperature to freeze popsicles is -18 degrees Celsius (-0.4 degrees Fahrenheit). At this temperature, popsicles will freeze in an average of two hours.

Tips for Making Cubed or Crushed Ice at Home


Cubed Ice 

ice-cube-tray

There are a few different ways to make cubed ice at home, but the most popular method is to use an ice cube tray.

To make cubed ice with an ice cube tray, fill the tray with water and freeze it for several hours.

Once the cubes are frozen solid, you can leave them in the tray, or remove and store them in a freezer-safe container for easy-access. 

You can also use disposable ice cube bags, which are cheap, easy to use, and convenient if you need a lot of ice at once.


Crushed Ice

blender-with-ice

There are a few different ways to make crushed ice at home, but the most popular method is to use an ice crusher

If you don't have an ice crusher, you can use a blender or food processor to crush the ice. Just be sure to leave some larger pieces intact, so that the ice doesn't melt too quickly when it's added to drinks.

Another option is to freeze water in plastic bags. This is a quick and easy way to make crushed ice, and it's perfect for margaritas or smoothies. 

Just fill a plastic bag with water, seal it shut, and freeze it for a few hours. Once it's frozen solid, you can break it into smaller pieces by gently hitting the ice with a hammer or mallet. 

How to Make Ice Melt Slower


Try this trick to keep your ice unmelted longer: make large cubes from just-boiled water.  

Boiling water before freezing eliminates air bubbles. Not only does this result in lovely translucent ice, but it also slows down melting.

And, just like tiny ice cubes freeze faster, big ice cubes melt slower! This is also a function of surface area; large cubes transfer less heat from the environment to the cube surface, meaning they melt less quickly.

You can also use a freezer that is set at a colder temperature. This will cause the ice to last longer than if the freezer were set at a higher temperature.

Another way is to add salt or sugar to the ice. The salt or sugar helps to lower the freezing point of water, which will keep the ice from melting as quickly.

You can also use a container that has a large surface area, such as a baking dish. This will help to slow down the melting process.

And finally, you can stir the ice constantly as it melts. This will help to distribute the heat evenly and prevent the ice from melting too quickly.


Does an Ice Maker Make Ice Faster than an Ice Cube Tray?


GE-Profile-Opal-Countertop-Nugget-Ice-Maker

A properly working ice cube maker should work much faster than an ice cube tray.

It freezes water in metal molds, which helps transfer heat away, cooling the ice more quickly.

It also uses refrigerant in compressor coils to cool trays (the refrigerant does not come in contact with the ice) rather than relying only on the ambient temperature of the cold air. 

Conclusion


Not only is it a pain to have to go get ice, but it can also be expensive. And if you're like most people, you probably don't have an endless supply of ice in your freezer.

Freezing and melting are governed by the laws of physics, so you may have thought there wasn’t much you could do to change it. Now you know that you can nudge the physics of freezing in your favor.

With our handy guide on how long it takes ice to freeze, you can utilize these tips, and you'll never have to worry about being caught without ice again.

Cheers,

Caitlin


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About the author

Caitlin is a Ph.D student and chocolate researcher at Colorado State University. Her research in the Food Science program focuses on chocolate fermentation (that’s right, it’s a fermented food!) and small-batch post-harvest processing techniques. When she is not acting in her capacity as resident chocolate guru, she researches other fermented foods and beverages like beer, sausage, and natto. Caitlin was drawn to fermented foods while living in rural Spain for six years, where she was exposed to traditional, time-honored practices of food preservation. At home, she practices Bollywood dance for fun and is followed everywhere by two small pet rabbits.

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