Steam canners are the latest, greatest thing in the canning world. Except they aren't really new; they've actually been around since the early 1900s. But in those early days, manufacturers struggled to get housewives to adopt a special tool for canning high-acid foods when an ordinary cooking pot was all that was necessary to preserve their fruits, jams, and pickles. They also struggled to help home canners understand that steam canners and pressure canners were different contraptions. (Steam canners are only a replacement for water bath canners and can not be used for safely preserving low-acid foods such as meat and non-pickled veggies.) 

Slowly, over the decades, steam canners faded from the home canning consciousness - until recent years, when there's been a surge of interest in them again. And, the truth is, there are some great reasons why you should consider using one. 

Steam Canning is Faster

The reason I became interested in steam canning is that it makes the job of canning faster. Modern steam canners use about 2 quarts of water, whereas a boiling water canner requires 16 or more quarts. Since it takes more time to boil a larger amount of water (and since many modern steam canners are made from lightweight materials that heat up quickly), the process of steam canning is considerably faster than traditional water bath canning. 

Steam Canners are Lighter 

Some people love steam canners because they are so lightweight. If you're accustomed to filling a water bath canner at the sink and then carrying the pot to the stove, or if you have to keep your canner in storage much of the year and hate lugging heavy pots out of the cupboard, you'll enjoy the fact that modern steam canners are extremely light as a feather.

Steam Canners Save Energy 

Obviously, if the canner brings water to a quicker boil, it's going to use less electricity, gas, or propane to operate your stove for canning. For example, with a traditional water bath canner, it can take 15 to 30 minutes to bring the water to a full boil, depending upon the power of your stove and what sort of fuel it uses. With a steam canner, however, it takes 10 minutes or less to get the water to a full boil. 

Steam canners are useful for quickly processing small batches.

Steam Canners May Work on Glass Top Stoves & Induction Burners 

Many home canners bemoan the fact that they have a glass top stove or induction burners that aren't safe to use with their traditional canners. At this time, the Victorio stainless steam canner (not their aluminum steam canner) is considered safe to use in with both. Other brands may follow suit. 

Parts of the Kitchen Crop dome-style steam canner.

As with nearly everything, there are also some downsides to steam canning: 

Steam Canners Don't Keep Empty Jars Warm 

If, like many canners, you're accustomed to putting empty jars in your water bath canner to preheat them, you'll have to use a different warming method when steam canning. Try keeping jars hot in the dishwasher, for example, or put them in a sink of hot tap water, or even fill them with hot tap water once or twice before filling each individual jar with food. 

Steam Canners are Specialized 

With water bath canning, any large pot with a lid and a rack on the bottom will work. With steam canning, you need an actual steam canner. (There are folks on the Internet using their pressure canners as steam canners, but this method has not been lab tested safe. More on this in a moment.) 

Parallax is an Issue 

The American Heritage Dictionary defines parallax as: "A change in the apparent position of an object relative to more distant objects, caused by a change in the observer's line of sight towards the object." In other words, depending upon your position, the position of something else may appear different than what it actually is. In modern life, we commonly experience parallax when we're typing on our phones. We think we are hitting certain letters with our fingers, but we are incorrect, due to parallax. Well, parallax is also a problem with modern steam canners. 

The style of steam canner currently tested safe by sources other than the manufacturer feature a gauge on the lid that faces the ceiling. It's important to read this gauge correctly, or you may not end up with a finished product that is shelf stable - but it can also be tricky to ensure you are looking straight down on the gauge, eliminating parallax. To get around this, my 5'2" self has to stand on a stepping stool, but even tall people should make it a point to carefully look straight down on the gauge. I do not recommend using a mirror or your phone to read the gauge, due to parallax. 

Due to parallax, great care must be taken in reading a steam canner gauge. These photos were taken at exactly the same time, but at slightly different angles. The first shows the gauge not quite meeting the black mark, which indicates the canner has not yet reached full temperature. The second photo makes it look like the gauge has reached full temperature.

Works for Shorter Processing Only 

Researchers recommend using modern steam canners for processing times of 45 minutes or less. The reason for this is that steam canners hold a lot less water than traditional water bath canners, and therefore may run out of water during longer processing times. However, a careful canner, who keeps the burner heat at the minimum to keep the water boiling, may be able to safely process jars for longer. This is a bit of a gamble, though, and you should run tests before canning any actual food. 

If the canner runs low on water, you cannot stop, add water, and then wait for the water to boil again; for safe food, it's essential that the processing time (using boiling water and the correct amount of steam) be uninterrupted and that the lid of the canner never be removed. Also, any canner that runs dry may warp and therefore be ruined. 

May Not Hold Many Jars 

Although my Victorio steam canner manual claims it holds 7 quart jars, it cannot hold that many wide-mouth (or mixed wide- and regular-mouth) jars and have the lid fit properly. If the lid doesn't fit securely on a steam canner, excess steam escapes, which will make the canner run out of water more quickly. An ill-fitting lid may also result in the canner not reaching the correct temperature to make canned food safe and shelf-stable. 

What Style of Steam Canner is Safe? 

At this time, the only steam canners that have been tested by a source other than the manufacturer and found to be safe are the dome-style canners, such as Victorio's (VKP's) Kitchen Crop. These look a bit like an old-school cake storage pan, with a short base and a domed top. For now, experts at the extension offices recommend we avoid other styles of steam canners for one important reason: Dome-style and stock pot style canners make the steam move differently.

Dr. Barbara Ingham, Professor of Food Science at the University of Wisconsin-Madison, explains the thermodynamics this way: "In a dome-style canner, steam vents at the base of lid – in the ‘stock pot’ style canners, steam vents out of the top of the lid. We know that heat circulates differently in the two systems...As scientists, we cannot state that our research applies to stock-pot style canners since we did not test those in the lab...in this case, we don’t have the evidence to support stock-pot style canners as steam canners." 

Quart jars of crushed tomatoes in a steam canner base.

Other Things to Note about Steam Canners 

1. When steam canning, use the same processing times that you would for a traditional water bath canner. As with water bath canning, processing time will vary according to your altitude. 

2. Keep the heat as low as possible while still keeping the water boiling and the gauge indicator in the correct position. Make small, incremental changes to temperature, as needed. If you allow the water to boil too vigorously, the contents of the jars will also boil too vigorously, leading to food coming out of the jars, resulting in seal failures (just as happens in the traditional water bath canner).

3. What about using a pressure or water bath canner as a steam canner by putting a small amount of water in the bottom of the canner, putting a rack in, and then waiting for steam to escape from the lid? The University of Wisconsin speaks directly to this method, saying they cannot recommend it: 

"In order for any canning process to ensure safe food is produced, there must be enough heat for a long enough time to kill pathogens and spoilage organisms that would make the product unsafe when stored on the shelf. We tested (steam) canners using thin thermometers, or thermocouples, tracking temperature at several points inside the canner and inside containers of several types of food to verify that the recommended canners and recipes would produce safe food. We compared our results to a boiling water canner that was used as recommended. For other steam canner styles or adaptations of a boiling water canner to be proven safe, a researcher would need to test the canner in a laboratory to ensure a safe product can be produced."  

In addition, modern steam canners have a gauge that must be read correctly for the altitude you live in; ensuring the gauge is in the correct setting during the processing time is essential for a safe end product. Neither pressure canners nor water bath canners have this style of gauge. 

My Kitchen Crop steam cammer.

General Directions for Using a Steam Canner 

Always read the manual that comes with your steam canner and follow the directions contained therein. However, the general process for steam canning is as follows: 

1. First do a temperature indicator test, which usually involves adding water to the canner, putting the lid on, and bringing the water to a boil. When the indicator on the gauge stops moving, the canner has reached its maximum temperature. Mark the location of the indicator on the gauge with a Sharpie. 

2. To begin canning, fill the bottom of the canner with water in the amount indicated in the manual. Add the rack. Preheat the water to just below boiling. 

3. Place filled jars with lids and rings on the rack. You can either fill the canner completely with jars or only process a single jar. 

4. Put the lid on the canner and bring the water to a boil. 

5. Begin your processing time when the indicator on the gauge reaches your Sharpie-marked line. Adjust the burner as needed to keep the indicator on this line, but keep stove heat to a minimum. 

 6. When the processing time is up, turn off the heat, but leave the lid on the canner. Wait 5 minutes. 

7. Remove the lid, and then the processed jars. 

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