For years, there has been a something missing from this site and that was a post that detailed the basics of boiling water bath canning. I didn’t do it in the very beginning and then, as time went on, I felt a little embarrassed about writing that kind of post so late in the game. Whenever people would ask me for it, I would refer them to other websites. However, I’m happy to finally be filling in that gap with this post here today.
So, a little disclaimer to start out with. I’m going to detail my particular canning workflow. This might not be exactly how you do it in your kitchen and that’s okay. We all find ways to make it work with the tools, equipment and space that we have. In the end, the most important things are that you get your jars hot, that you fill them to the proper headspace, and that you process them for the amount of time prescribed by your recipe. There’s a good deal of flexibility in the rest of the details.
As I mentioned in the first post in this series, any pot can be your canning pot as long as it’s tall enough to hold a rack and your jars, and that it allows the jars to be fully submerged in the water. I like this one, but the best pot to use is the one already in your kitchen. Once you’ve picked out your pot, position a rack in the bottom. I have a silicone trivet pictured here, but any round rack, collection of old canning jar rings or a hand towel will work. Then put your jars in the pot.
Then, fill up the jars and pot with water. I like to use the hottest tap water available, as it speeds up the boiling process a bit to start.
It’s a little hard to see in this picture, but at this point, I only fill the pot enough to just barely cover the tallest jar I’m using. This should be more than enough water for the processing stage, because once you lower your filled jars in the pot, they will displace enough water to sufficiently cover the jars (sometimes, you need to remove a little water from the pot to prevent overflow. If this becomes necessary, use something heatproof, like a Pyrex measuring cup so that you don’t burn yourself).
It is always a good idea to pour a generous glug of white vinegar into your canning pot before you start heating it. This will prevent any minerals present in your water from depositing on your canning pot or jars. I don’t live in a place with particularly hard water, but I still do this because it keeps my pot in good shape and makes it easier to clean.
Now the pot is ready to go on the stove an come to a boil. I do all of this before I ever apply heat to my preserves. That way, the canning pot has a head start on my product and the jars will be nice and hot when I’m ready to use them.
Here’s where my practice diverges a little from what the canning books will tell you. Almost all instructions (even those printed in my cookbook), will instruct you to take out a small saucepan, place the lids in it, cover them with water and bring it to a very gentle simmer. While this is good in theory (you don’t want to over soften the sealing compound), I rarely do it in practice. Instead, I watch my heating canning pot. When it reaches a boil, I turn it down to a simmer and drop my lids in. Everything stays nice and hot until I need to use it. The sealing compound gets to the perfect level of softness and I am a happy canner.
Recently, the experts at Ball Canning announced that it’s no longer necessary to simmer lids prior to canning, as the Plastisol sealant doesn’t require softening. Instead, just make sure to wash your lids in warm, soapy water before applying them to filled jars. More information about this can be found here.
When the product is ready to go into the jars, I slide the canning pot off the heat and pull out the jars with a handy jar lifter. Just a note: These jars are hot, but not sterilized, because I turn the heat down to a simmer as soon as the pot boils. This works because the filled jars get boiled for at least ten minutes (and often longer) during the processing step.
However, if your recipe calls for a processing time that is shorter than ten minutes, you either need to increase the processing time to ten minutes, or you need to actively boil your jars for at least ten minutes before filled, to ensure you have sterilized jars.
Now you fill up your jars, leaving the amount of headspace required by your recipe. If the recipe doesn’t tell you how much headspace to leave, go for approximately 1/2 inch. That’s typically enough for most products.
Before applying the lids and rings, wipe the rims with a damp paper towel (I use the hot water from the canning pot as my dampening water, as the heat helps remove any stubborn sticky spots. If your product is super sticky, a little white vinegar on the cleaning cloth will help).
Then, center a lid on each jar and secure it with a ring. Don’t over tighten the rings, because there needs to be enough space for the oxygen in the jars to escape. The term for this level of tightening is called “finger tip tight” meaning that you only tighten as much as you can with the tips of your fingers. I always tell my canning students that you turn just until the ring meets resistance.
Once all the jars have lids and rings, lower them into your canning pot. Make sure the jars are fully submerged and are covered with about an inch of water (you need that much to ensure that they won’t become exposed during boiling). Turn the burner to high. When the pot returns to a boil, set a a timer to the prescribed amount of processing time.
You do want to maintain an active boil throughout the processing of the jars, but make sure you control your boil. If the pot is madly rolling, the chances that you will burn yourself increase. Turn it down a little, to minimize splashing and injury.
When time is up, turn off the heat. If you have an electric stove that stays hot for a while, slide the pot off the burner. You don’t want the water to be rolling when you reach in with your jar lifter. Then, lift your jars out of the pot and place them on a folded kitchen towel to cool (if you have countertops made from marble, granite, stainless steel or some other surface that stays cool, the towel is really important so that you don’t shock your jars).
If you find that your product is leaking out of the jars when you pull them out of the canner, put the jars back in the water and let them cool gradually in the pot for five to ten minutes. One of the reasons that liquid loss occurs is that rapid cooling causes a powerful pressure differential that can forces product out of the jars. By letting your jars cool more slowly, you reduce the force of pressure and more product stays where you want it.
Once the jars are out of the canner, leave them alone and let them cool. Hopefully, you’ll hear a symphony of popping and pinging lids. This is good, it means that the seals are being formed. However, don’t freak out if you don’t hear those noises. Jars sometimes seal slowly and quietly. Once the jars are cool enough to handle, remove the rings and test the seals by holding onto the edges of the lids and lifting up an inch or two. If the lids hold fast, the seals are good.
Sealed jars should be stored in a cool, dark place without the rings. If the jars are at all sticky after processing, make sure to wash them before you put them away. Any sticky residue can attracts ants and other pests, so make sure your jars are squeaky clean.