The Pressure Side
What a pressure canner does that a boiling pot cannot, which gauge creates a yearly job, why an electric appliance is not the same machine, and where the dial-gauge altitude tables stop.
5 pages here.
A pressure canner is not a faster boiling pot. It is a different temperature. Low-acid food is sterilised at 240° to 250°F, and those temperatures are reached with a canner operated at 10 to 15 PSIG [F-1.2] — figures a pot of boiling water cannot produce at sea level, at altitude, or with any amount of extra time.
That is the whole reason this side of the site exists. Everything below is downstream of one sentence in the tested guidance: pressure does not destroy microorganisms, high temperatures applied for an adequate period of time do [F-1.8]. The pressure is the means. The temperature is the mechanism. Keeping those two apart is what makes the rest of these pages make sense, and collapsing them is how most of the bad advice in this subject gets written.
The five pages. What a pressure canner does that a boiling pot cannot, and what the guide's own timeline says you are signing up for. Dial gauge or weighted gauge — a real decision, because one of them creates a job you have to do every year and the other does not [F-3.5]. Whether an Instant Pot or an electric canner will do, which is the most heavily marketed question in home canning and the one where the honest answer has three parts rather than one. Venting, come-up and cool-down, which are parts of the process rather than the waiting around either side of it [F-3.3]. And what happens above 8,000 feet, where the USDA dial-gauge tables simply stop [F-4.2].
What is not here. No processing times, no pressures for a given food, no altitude table of ours. When you need one, these pages name the tested document that holds it and link you straight to it. That is deliberate: a site that retypes somebody else's table becomes a place where one typo can hurt a reader, and it cannot improve on the original anyway.
If you are choosing equipment rather than reading about it, start with the two questions that actually cost money — what the machine has to hold, and which gauge you want to live with. The minimum useful canner is one that holds four quart jars standing upright, and pressure saucepans below that are not recommended for canning [F-3.1]. The gauge question is on the second page below.
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What a pressure canner does that a boiling pot cannot
A pressure canner is not a faster boiling pot, it is a hotter one. Here is the temperature the tested guidance names, why pressure itself kills nothing, what Clostridium botulinum actually needs, and the guide's own timeline for a load.
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Dial gauge or weighted gauge, and the yearly job one creates
One of these gauges has to be checked for accuracy every year and the other does not. Here is what the tested guidance says about each, what the two-pound tolerance means, and where to get a dial gauge tested, including free by post.
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Can I use an Instant Pot or an electric canner
Three electric pressure cookers were put on a bench with data loggers in the jars and two never reached the temperature. Here is that data, why pressure is the wrong thing to measure, the one electric canner NCHFP excludes from its warning, and the model that is still an open question.
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Venting, come-up and cool-down: the parts people skip
Venting is a safety step, not a warm-up. Losing pressure restarts the clock from zero. Cooling is part of the heat treatment and must not be forced. Here is what the tested guidance says about each, and the one thing it admits it cannot quantify.
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Above 8,000 feet, where the tables stop
The USDA dial-gauge process tables have four altitude columns and the last one ends at 8,000 feet. Boiling-water and weighted-gauge tables do not stop. Here is exactly what is missing, what the published pressure ceiling is, and where the higher numbers in circulation actually come from.