# Sovereignty Module: Build the Kiln

## Complete Kiln Design and Construction: From Bricks to Firing Chamber

Building your own kiln is the potter's ultimate infrastructure project. This campaign covers kiln types, firebox design, flue systems, and construction from firebrick.

### Chapter 1: Kiln Types

| Type | Fuel | Max Temp | Complexity | Cost |
|---|---|---|---|---|
| Pit kiln | Wood | Cone 010 (1650°F) | Very low | Minimal |
| Barrel kiln | Wood | Cone 06 (1828°F) | Low | Low |
| Catenary arch | Wood or gas | Cone 10 (2345°F) | Moderate | Moderate |
| Sprung arch | Wood or gas | Cone 10 (2345°F) | Moderate | Moderate |
| Downdraft | Wood or gas | Cone 10 (2345°F) | High | Moderate |
| Cross-draft | Wood | Cone 10 (2345°F) | Moderate | Low-moderate |
| Anagama | Wood | Cone 10+ | High | Moderate |

### Chapter 2: Catenary Arch Kiln

Catenary arch: 1) The catenary curve is the natural shape of a hanging chain. 2) An arch in this shape supports itself without internal stress. 3) No steel reinforcement needed (the shape handles all forces). 4) Determine kiln size: interior width and height. 5) Create catenary template: hang chain between two points. 6) Trace chain curve onto plywood (this is your arch template). 7) Build form from plywood templates and cross-braces. 8) Lay firebrick over form. 9) Remove form after mortar sets.

| Kiln Size | Interior Width | Interior Height | Interior Depth | Cubic Feet |
|---|---|---|---|---|
| Small | 24 inches | 24 inches | 30 inches | 10 cu ft |
| Medium | 30 inches | 30 inches | 36 inches | 18 cu ft |
| Large | 36 inches | 36 inches | 48 inches | 36 cu ft |

### Chapter 3: Materials

| Material | Use | Quantity (Medium Kiln) |
|---|---|---|
| Hard firebrick (K-23) | Hot face (interior) | 200-300 bricks |
| Soft firebrick (K-26) | Insulation layer | 100-150 bricks |
| Ceramic fiber blanket | Outer insulation | 50-75 sq ft |
| Fireclay mortar | Brick joints | 100-150 lbs |
| Angle iron | Door frame, supports | 20-30 linear feet |
| Kiln shelves | Ware support | 6-10 shelves |
| Kiln posts | Shelf support | 12-20 posts |

### Chapter 4: Firebox and Flue

Firebox (wood-fired): 1) Located below or beside the kiln chamber. 2) Size: 1/3 to 1/2 of chamber volume. 3) Grate: steel bars for air flow under fuel. 4) Ash pit: below grate, allows ash removal. 5) Stoking port: large enough for wood loading. 6) Primary air: enters below grate (combustion air). 7) Secondary air: enters above fuel (completes combustion).

| Flue System | Type | Draft | Even Heating |
|---|---|---|---|
| Updraft | Hot air rises through ware, exits top | Natural | Fair (hot at top) |
| Downdraft | Hot air pulled down through ware, exits bottom | Forced or chimney | Good |
| Cross-draft | Hot air moves horizontally through ware | Natural | Fair (hot near firebox) |
| Bourry box | Separate firebox, flame enters chamber side | Natural | Good |

### Chapter 5: Construction Sequence

| Step | Task | Duration |
|---|---|---|
| 1 | Foundation: level concrete pad | 1-2 days |
| 2 | Floor: lay firebrick floor on sand bed | 1 day |
| 3 | Walls: lay firebrick walls to spring line | 2-3 days |
| 4 | Arch form: build plywood catenary form | 1 day |
| 5 | Arch: lay firebrick over form | 1-2 days |
| 6 | Insulation: apply soft brick and fiber | 1-2 days |
| 7 | Door: build removable brick door | 1 day |
| 8 | Chimney: build chimney and damper | 1-2 days |
| 9 | Curing fires: series of small fires | 3-5 days |
| 10 | First firing: test fire with test pieces | 1 day |

### Reference Card

1. The catenary arch is self-supporting (the catenary curve distributes weight so that every brick is in pure compression; no brick is under tension; this makes the arch incredibly strong without reinforcement). 2. Insulation saves fuel (a well-insulated kiln reaches temperature faster and uses less fuel; the investment in insulation pays for itself in fuel savings within a few firings). 3. The flue system determines even heating (the path that hot gases take through the kiln determines which areas are hotter and which are cooler; a well-designed flue system minimizes temperature variation). 4. Cure the kiln slowly (a new kiln contains moisture in the mortar and bricks; firing too hot too fast creates steam that can crack the structure; cure with a series of progressively hotter fires). 5. The firebox size determines maximum temperature (a firebox that is too small cannot generate enough heat to reach high temperatures; size the firebox at 1/3 to 1/2 of the chamber volume). 6. The chimney creates draft (the chimney draws hot air through the kiln; a taller chimney creates more draft; the damper controls the draft and therefore the atmosphere). 7. Building a kiln is the potter's declaration of commitment (a kiln is a permanent structure that says the potter is serious about the craft; it transforms a hobby into a practice). 8. Every kiln has a personality (no two kilns fire exactly the same; the potter must learn their kiln's hot spots, cold spots, and quirks through experience; this relationship between potter and kiln is part of the craft's magic).