Water-Bath Canning

The equipment

• Boiling-water canner: a deep pot with a rack and lid, deep enough for jars to be covered by 1 in. of boiling water with room to boil.
• Mason jars with two-piece self-sealing lids: a flat lid with a sealing compound and a reusable screw band ¹. Reuse jars and bands; use new flat lids each time. Unused lids seal well for about 5 years, so buy a year’s supply at a time ¹.
• A jar lifter, funnel, plastic bubble remover, ladle, clean towels, and a timer.

Commercial mayonnaise jars can be used with acid foods but break and fail to seal more often; other commercial jars aren’t recommended ¹.

Jars and lids

1. Wash jars in hot soapy water or a dishwasher and rinse well ¹.
2. Keep them hot: in simmering (180 °F) water in the canner, or in the closed dishwasher, until filling ¹. Hot jars don’t crack when filled with hot food.
3. Sterilize only when needed: jams, jellies, and pickles processed less than 10 minutes go into sterile jars. Boil empty jars 10 minutes, plus 1 minute for each 1,000 ft above 1,000 ft ¹. Foods processed 10 minutes or longer don’t need presterilized jars ¹.
4. Prepare lids per the manufacturer’s directions; don’t use dented or defective lids ¹.

Packing and headspace

• Hot pack: heat the food in syrup, water, or juice and fill hot; it removes air, shrinks food so more fits, and floats less.
• Raw pack: fill with raw food and cover with boiling liquid; quicker, but more floating and color loss.
• Headspace: 1/4 in. for jams and jellies, 1/2 in. for fruits and tomatoes in boiling water ¹, and as each recipe states.
• Release air bubbles by running a plastic spatula between food and jar; then readjust headspace ¹.
• Wipe the rim with a clean damp paper towel, center the lid, and tighten the band per the manufacturer, usually fingertip-tight ¹. Too loose leaks; too tight traps air and can buckle lids ¹.

Processing

1. Fill the canner halfway with water and heat it (about 140 °F for raw packs, 180 °F for hot packs).
2. Load filled jars on the rack; add boiling water until it’s 1 in. above the jar tops.
3. Bring to a full rolling boil, then start timing. Cover the canner.
4. If the boil stops at any point, bring it back and restart the timing from the beginning ¹. Add boiling water as needed to keep jars covered ¹.
5. When time’s up, turn off the heat, remove the lid, and wait 5 minutes before taking jars out ¹.

Altitude: use the recipe’s column for your elevation. For example, hot-packed peaches in quarts take 25 minutes at 0-1,000 ft and 30 minutes at 1,001-3,000 ft ¹.

Cooling and testing seals

Lift jars straight up with a jar lifter onto a towel, 1 in. apart, and let them cool undisturbed for 12-24 hours ¹. Don’t retighten bands. Then remove the bands and test each seal ¹:

• Press the center: a sealed lid doesn’t move; one that springs back isn’t sealed.
• Tap with a spoon: a sealed lid rings clear; a dull sound means no seal (or food touching the lid).
• Look across the lid: it should be slightly concave.

Unsealed jars: check the rim for nicks, use a new lid, and reprocess within 24 hours for the full time; or refrigerate and eat within several days; or freeze it, adjusting headspace to 1-1/2 in. ¹.

Try it

Can a small batch of applesauce or a fruit in a tested recipe: four pints. Keep a log of the date, recipe, elevation, pack, start and stop times, and how many sealed.

What to take from this

Use Mason jars with new two-piece lids, kept hot; sterilize only for jams, jellies, and pickles processed under 10 minutes. Leave the recipe’s headspace, release bubbles, wipe rims, and tighten bands fingertip-tight. Process at a full boil with jars covered by an inch of water, restart timing if the boil stops, adjust for altitude, wait 5 minutes, then cool 12-24 hours and test every seal. Reprocess, refrigerate, or freeze jars that didn’t seal.