In the last two days, I’ve gotten three different questions about canning on glass top stoves. And so, I figured it was high time that I added a blog post to the Canning 101 archive to explain why it’s not recommended and how you can potentially work around those warnings. Read on for more!
If you are the owner or regular user of a glass top stove, you may have heard that you’re not supposed to do any canning on your smooth, easy-to-clean stovetop. For long time canners who find themselves with these stoves, this news can be quite a blow.
There are three primary reasons why manufacturers recommend against canning on a glass top stove. The first is that many older canners have concave bottoms. When you combine a concave bottom with a flat surface, heat, and water, there is a risk that a seal will form between the canner and the stovetop. It’s not a huge deal until you go to move a canner that has suctioned itself to the stove. The seal can be strong enough that attempting to move the canner can result in a cracked or shattered stove top (this can also happen if you put a lid on your flat surface).
The second reason that it’s not recommended is that a full canner load of seven quart jars can be heavier that the stove top can bear. Even if your pot has a flat bottom, if it ends up weighing more that the glass surface can bear, you can still end up with a broken range.
The third reason is that some glass top stoves cycle the heat on and off, and so aren’t able to hold a steady boil. If you can’t hold a canner at a constant boil, you cannot guarantee that you’re getting the full level of heat penetration necessary for your preserves to be sterilized and safely shelf stable.
Happily, not all is lost for potential canners with flat glass top stoves. You can eliminate the risk of breakage through suction by using a pot with a flat bottom. A light-weight stainless steel stock pot (like this one) works well as a canning pot and will never seal itself to your stove. It also has the added benefit of being light enough to prevent the surface from cracking or breaking due to too much weight.
There is the issue of maintaining a rolling boil. Some stoves can do it and others can’t. Test your stove by bringing a pot of water to a boil and tracking the temperature with a candy thermometer while it boils. Does it stay at or near to 212 degrees F? Or does the temperature fluctuate a great deal? If you can maintain a rolling boil, you should be good to go.