What Are the 7 Stages of Clay in Correct Order?
Clay goes through 7 stages: Slip → Plastic → Leather Hard → Bone Dry → Bisque → Glaze → Fired. Each stage requires different techniques.
Quick Answer: The 7 Stages of Clay
- Slip - Liquid clay (like thick cream)
- Plastic - Moldable and workable (throwing stage)
- Leather Hard - Firm but carvable (trimming stage)
- Bone Dry - Completely dried (ready for bisque firing)
- Bisque - First fired (porous, ready for glaze)
- Glaze - Glazed and ready for final firing
- Fired - Final high-temperature firing (finished pottery)
Clay Stage Timeline
Slip Stage
Liquid clay consistency
What it is:
Slip is liquid clay mixed with water to a creamy consistency, like thick yogurt or pancake batter. It's the wettest form of clay.
What you can do at this stage:
- ✓ Use as glue to attach handles, spouts, and decorations
- ✓ Pour into molds for slip casting
- ✓ Decorate leather hard pieces with colored slip (slip trailing)
- ✓ Create slip decorations (marbling, sgr affito)
Common beginner mistakes:
❌ Trying to throw slip on the wheel (too wet)
❌ Applying slip to bone dry clay (won't stick)
💡 Tip: Make slip by mixing dry clay scraps with water. Store in an airtight container. Stir before use.
Plastic Stage
Moldable and workable - THE MAIN WORKING STAGE
What it is:
Plastic clay is soft, moldable, and contains 20-30% water. This is the stage where you do most pottery work. Clay is flexible, holds its shape, and can be molded without cracking.
What you can do at this stage:
- ✓ Throw on the pottery wheel (centering, throwing walls)
- ✓ Hand-building (pinch pots, coil pots, slab building)
- ✓ Sculpting (figurines, decorative pieces)
- ✓ Wedging (kneading to remove air bubbles)
How to test if clay is plastic:
Bend test: Roll a small coil and bend it. Plastic clay bends without cracking.
Feel test: Clay should feel soft, pliable, and slightly sticky.
💡 Tip: This is when you do 90% of pottery work. Keep clay moist by covering with plastic bags when not working.
Leather Hard Stage
Firm but carvable - TRIMMING & JOINING STAGE
What it is:
Leather hard clay is firm but still contains some moisture (10-15% water). It feels cool to the touch and holds its shape well but can still be carved, trimmed, and joined.
What you can do at this stage:
- ✓ Trim/turn (remove excess clay from the bottom, create foot rings)
- ✓ Add handles, spouts, decorations (use slip as glue)
- ✓ Carve designs (sgraffito, faceting)
- ✓ Join pieces (attach lids, assemble multi-part pieces)
- ✓ Smooth surfaces with damp sponge
How to test if clay is leather hard:
Touch test: Clay feels cool and damp but not wet. Doesn't stick to your hands.
Carve test: You can carve clean lines without clay crumbling or deforming.
Common beginner mistakes:
❌ Trimming when clay is too soft (deforms)
❌ Trimming when clay is too dry (cracks)
❌ Forgetting to cover pieces - they dry too fast
💡 Tip: Leather hard is the perfect stage for trimming. Too soft = deforms. Too dry = cracks. Check often!
Bone Dry Stage
Completely dried - READY FOR BISQUE FIRING
What it is:
Bone dry clay contains 0% moisture. It's completely dried, pale in color, and feels warm to the touch (not cool like leather hard). Clay is very fragile at this stage.
What you can do at this stage:
- ✓ Sand rough edges gently (use fine sandpaper)
- ✓ Load into kiln for bisque firing
- ✓ Final inspection (check for cracks, air bubbles)
What NOT to do:
❌ Add water or slip (causes cracks)
❌ Try to reshape or trim (will crack)
❌ Handle roughly (extremely fragile)
❌ Fire if not completely dry (water inside causes explosions in kiln)
How to test if clay is bone dry:
Touch test: Clay feels warm, not cool. No longer damp to touch.
Color test: Clay is noticeably lighter/paler than when wet.
⚠️ Important: Wait 5-7 days for thick pieces to dry completely. Firing wet clay = kiln explosions.
Bisque Stage
First fired - POROUS & READY FOR GLAZE
What it is:
Bisque (or biscuit) is clay fired once at 900-1000°C. The first firing hardens clay permanently but leaves it porous. Clay is now ceramic but not yet waterproof or food-safe.
What happens during bisque firing:
- ✓ Water molecules evaporate permanently
- ✓ Clay particles fuse together (vitrification begins)
- ✓ Organic materials burn out
- ✓ Clay shrinks 5-10%
- ✓ Clay becomes hard but porous
What you can do at this stage:
- ✓ Apply glaze (bisque is porous and absorbs glaze)
- ✓ Paint with underglazes or ceramic paints
- ✓ Sand rough spots (easier than bone dry)
- ✓ Wash pieces to remove dust before glazing
Characteristics:
• Color: Pale terracotta or cream (depends on clay type)
• Texture: Chalky, porous
• Sound: Makes a dull "thunk" when tapped
• Strength: Hard but brittle
💡 Tip: Bisque is stronger than bone dry but still fragile. Handle with care when glazing.
Glaze Stage
Glazed and ready for final firing
What it is:
Glaze stage is bisque-fired pottery coated with glaze, waiting for the final firing. Glaze is a glass coating that melts during high-temperature firing to create a waterproof, glossy surface.
What you do at this stage:
- ✓ Apply glaze by dipping, brushing, or pouring
- ✓ Wipe the bottom clean (glaze on the bottom sticks to kiln shelf)
- ✓ Apply multiple coats for even coverage (2-3 coats typical)
- ✓ Decorate with underglazes before or after glaze
Important notes:
• Glaze looks chalky and dull before firing
• Colors change dramatically during firing
• Test glazes before using on final pieces
• Keep glaze off the bottom 1cm of the piece
⚠️ Common mistake: Leaving glaze on the bottom = piece fuses to kiln shelf. Always wipe clean!
Fired Stage (Final)
Glaze fired - FINISHED POTTERY!
What it is:
Fired pottery has been through final high-temperature firing (1200-1300°C). Glaze has melted into glass, fused with the clay body. Pottery is now waterproof, food-safe, and fully functional.
What happens during glaze firing:
- ✓ Glaze melts and becomes glass (1200-1300°C)
- ✓ Clay vitrifies (becomes dense and waterproof)
- ✓ Colors develop (dramatic transformation)
- ✓ Piece shrinks another 5-10%
- ✓ Clay and glaze fuse together permanently
Final characteristics:
• Waterproof and food-safe (if food-safe glaze used)
• Glass-like surface - smooth and glossy
• Vibrant colors - glaze colors fully developed
• Rings when tapped - high-pitched ceramic sound
• Strong and durable - can last centuries
Now you can:
- ✓ Use as functional pottery (mugs, bowls, plates)
- ✓ Wash in dishwasher (most glazes)
- ✓ Use for food and drink (if food-safe glaze)
- ✓ Microwave (most stoneware)
🎉 Congratulations! Your pottery journey from wet clay to finished piece is complete. This is the stage everyone works toward.
Quick Reference Table
| Stage | Moisture | What You Do | Temperature |
|---|---|---|---|
| 1. Slip | 40-50% | Glue, decoration, slip casting | Room temp |
| 2. Plastic | 20-30% | Throwing, hand-building, sculpting | Room temp |
| 3. Leather Hard | 10-15% | Trimming, joining, carving | Room temp |
| 4. Bone Dry | 0% | Sanding, prepare for firing | Room temp |
| 5. Bisque | 0% | Glazing, painting | 900-1000°C |
| 6. Glaze | 0% | Wait for final firing | Room temp |
| 7. Fired | 0% | Use & enjoy! | 1200-1300°C |
Common Mistakes by Stage
❌ Working at the wrong stage
Trying to trim plastic clay (too soft) or bone dry clay (cracks). Learn to recognize each stage.
❌ Letting clay dry unevenly
Thin areas dry faster than thick areas, causing cracks. Cover pieces with plastic, dry slowly.
❌ Firing clay that's not bone dry
Moisture trapped inside causes explosions in the kiln. Wait 5-7 days for thick pieces to dry.
❌ Glazing the bottom of pieces
Glaze on the bottom fuses to the kiln shelf. Always wipe the bottom 1cm clean.
Related Questions
When do you trim pottery?
Trim during the leather hard stage (stage 3). Clay is firm enough to hold its shape but soft enough to carve. Test by pressing with your thumbnail - it should leave a mark but not squish.
Can you skip bisque firing and glaze directly?
No, you need bisque firing first. Bisque makes clay hard enough to handle during glazing and porous enough to absorb glaze. Single-firing (raw glazing) is possible but difficult for beginners.
How long does each stage take?
Timeline from start to finish:
- • Plastic → Leather hard: 12-24 hours (covered)
- • Leather hard → Bone dry: 3-7 days (uncovered)
- • Bisque firing: 8-12 hours + 8-12 hours cooling
- • Glazing: 1-2 hours
- • Glaze firing: 8-12 hours + 12-24 hours cooling
- Total: 2-3 weeks from wet clay to finished piece
Learn Clay Stages Hands-On
Understanding clay stages is crucial for pottery success. Take a class where you'll work through all 7 stages with expert guidance.