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Terms for Canning: A Guide for New Canners
If you're new to pressure canning, the lingo can feel like its own language. Canning is the process of preserving food by packing it into jars and processing it to create a safe, sealed environment for long-term storage, and terms like headspace, venting, and siphoning tell you how to do that safely.
We put together this quick-reference guide for new or inexperienced pressure canners who want to understand what a recipe is asking them to do before, during, and after processing. It walks through key canning terms and steps, from headspace, hot pack, and raw pack to pressure management, altitude adjustments, cooling, sealing, and testing seals, so you can avoid common mistakes and can with confidence.
Before You Start Home Canning
Headspace The empty space left between the top of your food/liquid and the rim of the jar in this food preservation method that destroys microorganisms and inactivates spoilage enzymes. Recipes will always tell you how much to leave (usually ¼" to 1¼", depending on what you're canning). Too little headspace and food can bubble out during processing; too much and your jar might not seal properly.
Hot Pack Filling jars with food that's already been heated (like a soup or pre-cooked veggies) before processing.
Raw Pack Filling jars with raw, unheated food, then adding hot liquid before processing. Common for things like meat and some vegetables.
Fingertip Tight How tight your lid band should be before processing — snug, but not cranked down. Check jars carefully for nicks or cracks before use. Too tight and air can't escape during processing, which can prevent a proper seal. Use new flat metal lids each time. Wipe jar rims clean with vinegar before sealing to help ensure a good seal.
During Pressure Canning
Venting (or Vent Time) Before you start your processing time, you have to let steam escape through the vent pipe for about 10 minutes to push out any trapped air in the pressure canner. This step is non-negotiable — skipping it can throw off your internal canner temperatures and processing accuracy.
Vent Pipe The small pipe/opening on top of your pressure canner where steam escapes during venting, and where your pressure regulator weight sits.
Pressure Regulator Weight The rocking weight that sits on the vent pipe once venting is done. It "jiggles" or rocks to indicate you've reached (and are maintaining) the correct pressure.
Pressure Gauge A dial with a needle that shows your pressure reading. Our gauge is accurate +/- 2 lbs, and is used only as a reference, and to determine when the cover can be safely removed, which is when the steam gauge returns to zero.
Pressure Buildup The period after venting where your canner climbs up to the pressure your recipe calls for.
Processing Time The actual amount of time your jars need to spend at pressure — this is what actually makes your food safe to store at room temperature.
Altitude Adjustment Pressure needed to safely process food changes based on your elevation. Most recipes list adjustments for higher altitudes — always double check before you start canning, and follow tested recipes plus manufacturer instructions and support directions from authoritative sources.
After Boiling Water
Pickup Time (or Cooling Time) Once your processing time is done, you turn off the heat and let the canner naturally depressurize — no quick-releasing, no lifting the weight early.
Siphoning When liquid gets pulled out of the jar during or after processing, usually because of a rapid pressure change. A little siphoning liquid loss won't ruin your seal, but it's a sign to slow down your process next time.
Sealing As jars cool, the lid pulls down and seals as a vacuum forms inside; canning jars are made to withstand the heat and pressure of processing, and a reliable seal depends on using new flat metal lids each time. You'll often hear a "ping" — that's the sound of a successful seal!
Testing the Seal After jars have cooled completely (usually 12-24 hours), press the center of the lid. If it doesn't flex or pop, you've got a good seal. You can also tap lids lightly with a teaspoon after cooling to help confirm the seal. If it flexes, refrigerate and eat that jar soon rather than storing it on the shelf. Properly sealed jars can be stored at room temperature for months or even years, and canned goods often last over a year in a cool, dark place. Never taste food from jars that show signs of spoilage.
The Bottom Line
Pressure canning has a learning curve, but once you know the terms, the process makes a lot more sense, and canning is also a cost-effective way to preserve seasonal harvest produce. Every step — venting, building pressure, processing time, pickup time — exists to keep your food safe and your seals solid.