Complete Kiln Loading and Firing Schedule: From Raw Ware to Finished Pottery
⟁ cover painted for this edition — the source module carried no illustrations
Complete Kiln Loading and Firing Schedule: From Raw Ware to Finished Pottery
Kiln firing transforms fragile clay into permanent ceramic. This campaign covers loading strategy, firing schedules, cone systems, atmosphere control, and troubleshooting.
Chapter 1: Firing Stages
Stage
Temperature Range
Duration
What Happens
Water smoking
Room temp to 400°F
2-4 hours
Remaining moisture evaporates
Burnout
400-1000°F
2-3 hours
Organic matter burns out
Quartz inversion
1063°F (573°C)
Slow through
Quartz crystal structure changes
Sintering
1000-1650°F
2-3 hours
Clay particles begin bonding
Vitrification
1650°F to target
2-4 hours
Glass forms between particles
Soaking
Target temperature
15-30 minutes
Even heat distribution
Cooling
Target to room temp
12-24 hours
Controlled cool-down
Chapter 2: Kiln Loading
Loading Rule
Specification
Why
No touching
1/4 inch between pieces
Pieces fuse if touching
No shelf contact (glazed)
Wax foot, kiln wash shelf
Glaze bonds to shelf
Even distribution
Spread weight evenly
Prevents shelf warping
Tall pieces center
Short pieces at edges
Even heat distribution
Airflow gaps
Leave gaps between rows
Heat must circulate
Lid on pot
Fire lid on matching pot
Ensures fit after shrinkage
Loading strategy: 1) Plan loading before starting (dry fit). 2) Bottom shelf: heaviest pieces. 3) Middle shelves: medium pieces. 4) Top shelf: lightest, smallest pieces. 5) Leave 1/2 inch clearance above tallest piece on each shelf. 6) Do not block flue or chimney opening. 7) Place cone packs at top, middle, and bottom (monitor temperature).
Chapter 3: Firing Schedules
Bisque firing (cone 06, 1828°F): 1) Room temp to 200°F: 1 hour (100°F/hour). 2) 200°F to 400°F: 2 hours (100°F/hour). 3) 400°F to 1000°F: 3 hours (200°F/hour). 4) 1000°F to 1063°F: 1 hour (slow through quartz inversion). 5) 1063°F to 1828°F: 3-4 hours (200°F/hour). 6) Hold at 1828°F: 15 minutes. 7) Turn off kiln, cool naturally (do not open until below 200°F).
Firing Type
Target Cone
Target Temp
Total Time
Atmosphere
Bisque
06
1828°F
10-12 hours
Oxidation
Low-fire glaze
06-04
1828-1940°F
8-10 hours
Oxidation
Mid-fire glaze
5-6
2167-2232°F
10-12 hours
Oxidation or reduction
High-fire glaze
9-10
2300-2345°F
12-14 hours
Reduction
Salt/soda
10
2345°F
12-14 hours
Reduction + salt/soda
Chapter 4: Atmosphere Control
Atmosphere
Method
Effect on Glaze
Effect on Clay
Oxidation
Full air supply
Bright, clean colors
Light body color
Reduction
Restricted air
Muted, complex colors
Dark body color
Neutral
Balanced air
Between oxidation and reduction
Moderate body color
Heavy reduction
Very restricted air
Carbon trapping, metallic
Very dark body
Reduction firing: 1) Begin in oxidation (full air) through bisque temperatures. 2) Start reduction at cone 010 (1650°F). 3) Reduce by closing damper partially. 4) Flame should lick out of spy holes (positive pressure). 5) Maintain light reduction through firing. 6) Heavy reduction at end (last 30 minutes). 7) Reduction starves the kiln of oxygen. 8) Iron in clay and glaze changes color (red to gray/brown).
Chapter 5: Troubleshooting
Problem
Cause
Solution
Cracking
Too fast through water smoking
Slow down below 400°F
Bloating
Too fast at high temperature
Slow down above 2000°F
Dunting
Too fast cooling through quartz inversion
Do not open kiln above 1100°F
Glaze crawling
Dusty bisque surface
Clean bisque before glazing
Glaze pinholing
Insufficient soaking time
Extend soak at peak temperature
Uneven firing
Poor loading, blocked airflow
Improve loading, check flue
Under-fired
Insufficient temperature
Check cones, extend firing
Over-fired
Excessive temperature
Check cones, reduce time
Reference Card
Never rush the water smoking stage (moisture trapped in clay expands to steam at 212°F; if the kiln heats too fast, steam pressure shatters the pottery; the first 400°F must be slow). 2. Quartz inversion is the danger zone (at 1063°F, quartz crystals in clay change structure and expand; heating or cooling too fast through this temperature causes cracking (dunting); go slow). 3. Cone packs are essential (pyrometric cones measure heat work (time + temperature); a thermometer alone is not sufficient; cones placed at top, middle, and bottom reveal temperature variations). 4. Do not open the kiln until cool (opening a hot kiln causes thermal shock that cracks pottery; the kiln must cool to below 200°F before opening; patience is the final step of firing). 5. Reduction changes everything (restricting oxygen during firing causes chemical changes in clay and glaze; iron turns from red to gray, copper turns from green to red; reduction is the potter's alchemy). 6. Even loading ensures even firing (pieces packed too tightly block airflow; pieces loaded unevenly cause hot and cold spots; thoughtful loading is as important as the firing schedule). 7. Every kiln is different (firing schedules are guidelines, not rules; each kiln has its own personality, hot spots, and quirks; the potter must learn their specific kiln through experience). 8. Firing is the moment of truth (all the work of preparing clay, throwing, trimming, glazing, and loading comes down to the firing; a successful firing transforms fragile clay into permanent, beautiful ceramic).
