Cooking Pots

Part of Pottery and Ceramics

Making heat-resistant ceramic cooking vessels that withstand direct flame contact and thermal shock.

Why This Matters

Cooking pots are among the most critical items a rebuilding community needs. Before metal cookware can be manufactured — which requires mining, smelting, and forging infrastructure — ceramic cooking vessels are the only practical option for boiling water, making stews, rendering fat, brewing, and dozens of other thermal processes essential to survival.

But a cooking pot faces demands no other vessel does. It must survive being heated to several hundred degrees on one side while the other side remains relatively cool. It must tolerate being placed on a fire while containing cold water, then cool down after cooking — over and over, daily, for months or years. Ordinary pottery shatters under these conditions within days.

Making cooking pots that last requires specific choices in clay selection, temper, forming technique, wall thickness, and shape. These aren’t arbitrary traditions — they’re engineering solutions developed over millennia of empirical testing. Understanding why each choice matters lets you produce reliable cooking vessels from whatever clay sources are available in your area.

Clay Body for Cooking Vessels

Thermal Shock Resistance

When a pot is placed on fire, the flame side expands from heat while the opposite side stays cool. This differential expansion creates internal stress. If the stress exceeds the clay’s strength, the pot cracks — usually on the first or second use.

The key to thermal shock resistance is controlled porosity. A slightly porous clay body with well-distributed temper particles can flex microscopically, absorbing expansion stresses without fracturing. A dense, vitrified body is rigid and shatters.

Ideal Temper for Cooking Pots

Temper Material	Thermal Shock Rating	Notes
Crushed shell (calcium carbonate)	Excellent	Converts to lime during firing, creates ideal porous structure. Traditional choice worldwide.
Grog (crushed fired pottery)	Very Good	Predictable, stable. Use crushed cooking pots that failed for poetic recycling.
Quartz sand (angular)	Good	Widely available. Use angular-grained sand, not round — angular grains lock into the clay matrix better.
Ite (volcanic rock fragments)	Good	Lightweight, naturally porous. Excellent where available.
Chopped grass/straw	Moderate	Burns out during firing, leaving pores. Works but produces weaker vessels.

Recommended recipe: 70-75% plastic clay, 25-30% crushed shell or grog, by volume. This produces a body with excellent thermal shock resistance while maintaining enough plasticity to form easily.

Crush Shells Finely

Shell temper must be crushed to particles no larger than 2-3 mm. Larger fragments create weak points. Grind between two stones or pound in a wooden mortar.

Clay Body Preparation

1. Wedge the clay and temper together thoroughly — the temper must be uniformly distributed, not clumped
2. Age the mixed body for at least 1-2 weeks if possible — aging improves plasticity, which helps with forming thin, even walls
3. Re-wedge immediately before forming

Designing the Shape

Cooking pot shape is not aesthetic — it’s functional engineering:

Round Bottom vs. Flat Bottom

Round-bottomed pots are thermally superior:

• Heat distributes evenly across the curved surface
• No sharp corners where stress concentrates
• Sits naturally in a bed of coals or on a three-stone fire support
• Traditional cooking pot shape across most cultures for good reason

Flat-bottomed pots are practical for:

• Standing upright on flat surfaces (tables, shelves)
• Use on flat-topped stoves or cooking platforms
• The flat-to-wall angle is a stress concentration point — reinforce with extra thickness

Wall Thickness

Pot Size	Recommended Wall Thickness	Base Thickness
Small (0.5-1 liter)	5-7 mm	7-8 mm
Medium (2-5 liters)	6-8 mm	8-10 mm
Large (5-15 liters)	8-10 mm	10-12 mm

Uniform thickness is more important than absolute thickness. A pot with 7mm walls throughout will outlast one that varies from 5mm to 10mm, because uneven thickness means uneven thermal expansion.

Rim Design

The rim takes the most abuse — it’s gripped, bumped, and subjected to thermal stress where it transitions from fire-heated walls to cooler air:

• Rolled rim: Fold the top edge outward and down, creating a doubled rim. Strongest option.
• Thickened rim: Add an extra coil at the top and smooth it to create a lip 50% thicker than the walls.
• Flanged rim: An outward-projecting rim that supports a lid and provides a grip surface.

Forming Techniques

Coil Building for Cooking Pots

Coil building is the traditional method for cooking pots and remains superior to wheel throwing for this application:

1. Form a base using a coil spiral — this eliminates the weak center point that slab bases have
2. Build walls with coils, scoring and slipping every joint
3. Use the paddle-and-anvil technique to thin and compact walls:
   • Hold a smooth stone inside the pot
   • Strike the outside with a flat wooden paddle
   • Work systematically, rotating the pot
   • This welds coil joints thoroughly and compresses the clay body
4. Shape the profile as you go — belly out for maximum volume, curve in for a narrower opening

Coil Joints Are Weak Points

In a cooking pot, an insufficiently welded coil joint will crack under thermal stress within a few uses. Paddle-and-anvil technique is not optional for cooking pots — it’s the step that makes them survive.

Mold-Formed Cooking Pots

For production efficiency, use a hump mold (convex form):

1. Shape a round stone or fired clay form into the interior shape of your pot
2. Drape a clay slab over the mold
3. Paddle the clay onto the mold to shape the bottom half
4. Let it firm slightly, remove from mold
5. Add coils to build up the upper walls and rim
6. Paddle-and-anvil the entire surface for final shaping and compression

Adding Handles and Lugs

Cooking pots need gripping points for safe handling when hot:

• Lug handles: Small ear-shaped projections attached to the upper walls. Score and slip the attachment points thoroughly.
• Strap handles: Flat, wide handles that distribute grip force. Attach at two points, well-scored and slipped.
• Rim notches: Cuts in the flanged rim for placing a lifting stick across the top

Handles are the most common failure point. Reinforce every handle attachment with extra clay pressed around the joint, blending carefully into the wall. The handle should be the same clay body as the pot — if they have different shrinkage rates, the handle will crack off.

Firing Cooking Pots

Temperature Range

Cooking pots should be fired at a moderate temperature — typically 750-900°C (cherry red to bright cherry red):

• Underfiring (below 700°C): Too weak, crumbles with use
• Ideal range (750-900°C): Strong enough for daily use, porous enough for thermal shock resistance
• Overfiring (above 1000°C): The body vitrifies (becomes glass-like), losing porosity and thermal shock resistance

Vitrified Pots Crack on Fire

A stoneware-fired pot placed directly on an open flame will crack. High-fired pottery is stronger in general use but weaker under thermal shock. Fire cooking pots at earthenware temperatures.

Firing Schedule

1. Candling (0-200°C): Very slow — 1-2 hours. This drives out residual moisture safely.
2. Smoking (200-400°C): Moderate rise. Organic material in the clay burns out. Sooty flames are normal.
3. Red heat (600-900°C): Continue steady rise to target temperature. At 573°C, quartz particles in the clay undergo a sudden volume change (quartz inversion) — pass through this range steadily, not abruptly.
4. Soak: Hold at peak temperature for 20-30 minutes to equalize heat throughout the kiln.
5. Cooling: Let the kiln cool completely before opening — ideally overnight. Rapid cooling causes thermal shock cracking, defeating the entire purpose.

Seasoning and First Use

A newly fired cooking pot benefits from seasoning before its first cooking use:

1. Soak in water for 12-24 hours. This fills the pores with water, reducing the thermal shock of first heating.
2. First heating — gentle: Place the pot near a small fire, gradually moving it closer over 30-60 minutes. Don’t plunge a cold pot into flames.
3. Grease seasoning: Rub the interior with animal fat or plant oil. Heat gently until the oil smokes and absorbs into the pores. Repeat 2-3 times. This creates a semi-waterproof coating and improves non-stick properties.
4. First cooking — liquid: The first several meals should be soups, stews, or boiled water — liquids that provide even heating. Avoid dry roasting or frying until the pot has several uses behind it.

Extending Pot Life

Daily Use Practices

• Always warm pots gradually — never place a cold pot on a roaring fire
• Never add cold water to a hot pot — thermal shock
• Clean with warm water while the pot is still warm, not by plunging hot pots into cold wash water
• Store pots dry to prevent mold growth in the porous walls
• Re-season periodically with oil if the interior becomes rough or absorbs flavors

Repair

Small cracks in cooking pots can sometimes be sealed:

• Mix fine clay with water to form a thick slip
• Fill the crack, pressing firmly
• Let dry slowly
• Re-fire if possible, or simply use — the sealed crack may hold for weeks to months
• A pot with a sealed crack is still better than no pot

Expected Lifespan

With proper clay body, forming, firing, and use:

• Daily-use cooking pot: 6-18 months
• Occasional-use pot: 2-5 years
• Water-heating only (no direct flame): 3-10 years

Plan your pottery production to maintain a rotating stock of cooking vessels. A household needs 3-5 cooking pots of various sizes, plus 1-2 replacements in production at all times. For a community of 20 people, that means maintaining 15-25 active cooking pots and producing 2-3 replacements per month.