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Storage & food preparation · Fermentation vessel

Fermentation jar / crock

A heavy ceramic crock or glass jar with weights and an airlock for fermenting vegetables like sauerkraut and kimchi.

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What it is

A thick-walled stoneware crock, often with a water-sealed moat around the lid, or a glass jar fitted with an airlock lid. Weights keep vegetables submerged under brine so they ferment without mould. Gas escapes but air is kept out.

What it’s for: Lacto-fermenting vegetables and making pickles in a controlled environment.

How to use it

  1. Clean the vessel thoroughly.
  2. Pack salted vegetables tightly and press until brine covers them.
  3. Place the weights on top so everything stays under the brine.
  4. Seal (fill the water moat or fit the airlock) and leave at cool room temperature, checking regularly.

Good to know

Tasks
making sauerkraut and kimchi, fermenting pickles, fermenting hot sauce mash, making kanji or kvass
Cooking methods
Fermented
Materials
stoneware, glass, ceramic weights
Care and cleaning
Wash with hot water and dry completely; avoid harsh detergents on unglazed stoneware. Store with the lid off.
Limitations
Heavy and bulky; temperature affects timing.

Safety

  • Keep food under the brine.
  • Discard ferments with fuzzy coloured mould or a putrid smell.
  • Use lead-free, food-safe glazes.

If you don’t have one

  • Glass jar with lid — Use a weight or small bag of brine to keep vegetables under; open daily to release gas.

Equipment guide

How it works: A crock holds vegetables below their brine with weights, excluding oxygen so lactic acid bacteria can outcompete moulds. A water-filled moat around the lid lets carbon dioxide out but keeps air from getting in.

MaterialGoodWatch out
Glazed stonewareTraditional; holds a stable temperature; large capacity.Heavy; check glaze is food-safe and lead-free.
GlassNon-reactive, does not absorb smells or stains, lets you see the contents, easy to sterilise.Breakable; clear glass lets light degrade light-sensitive foods such as spices and oils.
Food-grade plasticLight.Scratches; can hold smells.
Unsuitable: reactive metalsNone.Acids react with aluminium, iron or copper.
Water-seal crock
Moat around the lid.
Open crock
Covered with cloth; needs more watching.
Jar with airlock lid
Small batches.

Buying guidance

Starting out: A 1–2 litre glass jar with an airlock lid and a glass weight.

Keen cook: A 5–10 litre water-seal stoneware crock with weights.

  • Capacity for your batch
  • Weights that keep food under brine
  • Lead-free glaze
  • Water-seal or airlock

No brands or prices — check current reviews before buying.

Techniques:FermentationPickling

Related tools

Recipes that use it