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Using a Pressure Canner as a Steam Canner
I only own one canner. It is a good one, a Presto 23 qt Pressure Canner, which is large enough to double decker pint jars, and even tall enough to can half gallons, or to use as a water bath canner with the actual recommended water coverage.
This canner does everything. But I don't use it as a WB canner. Too much water, too much time heating the water, more of a hassle filling the thing.
I use it as a steam canner. (For those who are unaware, steam canners ARE approved for canning in the US by "official" sources. Look it up, I don't have time to cite sources.)
A Steam Canner is used in place of a Water Bath canner. It uses hot steam, instead of hot water, to heat the jars and process them. Steam canners use the SAME TIMES as Water Bath canners. Using your Pressure Canner as a steam canner can save you the cost of the steam canner, and you can even avoid the cost of a water bath canner also if you like.
To use a pressure canner as a steam canner, follow this procedure:
1. Add 1 more quart of water to the bottom than you would add for pressure canning. For my canner, this means 4 quarts instead of 3 quarts. You need a little more water since it will steam the whole time, instead of having the steam contained. In all the times I've done it, 4 quarts has been more than enough. See the note below for cautions.
2. Put the jars in. Stack them if you want. Water does NOT need to even touch them (if you are stacking), because they will be surrounded by steam that is actually hotter than the water.
3. Put the lid on like you normally would, lock it into place.
4. Turn on the heat. I start it on high.
5. Wait until the safety latch pops up. (The safety latch will not pop up until there is sufficient steam pressure inside to lift it, and it won't do that until all the air is exhausted, so it is an accurate indicator for starting the time for steam canning, or putting the weight on for pressure canning.) If your canner does not have a safety latch, then wait until it is steaming hard through the vent.
6. Start timing. Use the NORMAL time for Water Bath canning. DO NOT PUT ON THE WEIGHT. Just let it steam. You can turn the heat down, just make sure it stays steaming hard (you will hear the water boiling inside and the latch will stay up).
7. When the time is up, turn off the burner. (Move it if you want to - I don't, because I have a heavy canner, on a glass top stove - the Presto 23qt that I have is made to be safe on glass tops.)
8. Let it cool until the safety latch drops, or until it is no longer steaming visibly.
9. Go ahead and open the canner and remove the jars. (If you are having problems with liquid loss, let the jars cool a little with the lid set on at an angle for about 10 minutes before removing the lid entirely, then let them cool for another 10 minutes before removing them from the canner.)
CAUTION: Don't use this for things that need to process for more than about 45 minutes unless you add another quart or two of water. I've done things that took 30 minutes, and it still had a lot of water left in it.
You want to make ABSOLUTELY SURE you do NOT use this as an "alternative" to pressure canning.
Not only is it just better to pressure can if you have the equipment to do so, you risk running it out of water on long steam cycles. That's bad, it can crack your jars and crack or even melt your canner - generally it will at least warp the bottom, and that IS A RISK for having the canner crack during a pressure cycle in the future.
HOW DO YOU KNOW IF IT RUNS OUT OF WATER? You won't see or hear steam coming out, you won't hear boiling, and the safety latch will drop. After a bit, you will smell the smell of hot metal (possibly combined with the smell of burning food residues if the jars have leaked any liquid) - not a nice smell to have in your kitchen!
If this happens, turn off the burner and MOVE THE CANNER off the burner, and let it cool down COMPLETELY, without disturbing it (you cannot tell how hot it is inside, and if you open the top too soon you risk cracking the jars from sudden exposure to cold air). Once it is completely cool, remove the jars, check the canner for warps or cracks, check the jars for damage, etc. If it is still usable, fill it again, but use MORE water, and try again.
IT IS MOST IMPORTANT that you DO NOT run water into the canner until it is COMPLETELY COOLED. Running water into the canner while it is as hot as it gets without water in it, can warp or crack the canner, and if there are hot jars in it, it can shatter the jars.
The chance of this happening with a normal canning run is pretty well impossible. So don't get all worried because I put this in there. I'm just putting it in there for those who might use it improperly, or for those who wonder what the chances are that it might run out of water and what would happen if it did!
If food residues get burned onto the canner, it may stain it badly, and you may need to scrub it with an SOS pad, or fill it with water to the top of the stains, and then add a few cups of vinegar to the pot and boil it for a while.
Now... If this has EVER happened, you'll need to watch the canner in the future, and be alert for progressive warping of the bottom of the canner.
If the canner has run dry at any time, the heat on the bottom is higher than normal during the disaster, so the bottom can kind of start to round out a bit instead of being flat. If that appears to be happening, it is not safe to use it anymore as a pressure canner.
There is a small possibility that it could crack during a pressure canning run if it has warped due to abnormallly high heat exposure, and this is no small thing. Also listen for atypical sounds during pressure canning runs, and respond quickly (this is something we usually do anyway, it is kind of instinctive).
That's a lot more detailed than I'd normally be, but hopefully that will answer all the questions anyone has.
I've been doing this for probably 40 years, since I started doing it when I was in my teens in my mother's house. I've never had an unfortunate episode with it, in any way whatsoever. It has been a very efficient and easy way to waterbath high acid foods.
The information on this site is presented for informational purposes only, and consists of the opinions and experiences of the site authors. It is not to be construed as medical advice or to be used to diagnose or treat any illness. Seek the assistance of a medical professional in implementing any nutritional changes with the goal of treating any medical condition. The historical and nutritional information presented here can be verified by a simple web search.
I do what I do because I understand the science behind it, and I've researched worldwide sources to verify the safety of my practices to my own satisfaction. Please do your own research, and proceed AT YOUR OWN RISK.