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📋 Ingredients
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Common starting materials: Feldspar, Whiting, Silica, EPK Kaolin.
Common starting materials: Feldspar, Whiting, Silica, EPK Kaolin.
🔮 Theoretical Outcome
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Recipe
📋 Recipe Ingredients
All materials in this recipe — base glaze and colorant/stain additions.
📋 Recipe at a Glance
Key numbers that tell you if this glaze is balanced and safe to fire
🎓 Glaze Story
A plain-English explanation of what this glaze is doing chemically — its flux character, surface prediction, and thermal expansion.
⚗️ What's In Your Glaze (Weight %)
This shows how much of each chemical oxide is in your fired glaze, by weight. Each oxide has a job — see the descriptions below.
🔬 Unity Molecular Formula (UMF)
UMF is the potter's chemistry language. It shows the ratio of oxides relative to each other — not weight, but molecular proportion. The fluxes always add up to 1.0, so you can compare any two glazes directly.
How to read this: Each number tells you how many molecules of that oxide are present for every 1.0 total flux molecule. A higher number = more of that oxide in the glaze. Fluxes melt the glaze. Silica forms the glass. Alumina stiffens and stabilizes it.
💚 Glaze Health Check
These bars show whether your glaze is in the safe, proven range for a good result. Green ✓ means you're on target. Orange ⚠️ means it may be too low or too high — adjust your recipe.
The Stull chart maps your glaze's Silica and Alumina values onto a grid that predicts the surface quality — matte, satin, or glossy.
🟠 Starting glaze chemistry · 🔵 Drag to change the chemistry
🎯 Chemistry Studio
Explore oxide targets and develop a workable recipe.
Enter values to see chemistry
🎯 UMF Source Selector
The fluxes (K₂O, Na₂O, Li₂O, CaO, MgO, BaO, SrO, ZnO) must always sum to exactly 1.0 — that is the Unity rule. The numbers on the oxides are proportions of that 1.0. Click 📦 Sources on any oxide to see which materials provide it.
Stull Chart
🔵 Target · 🟠 Your Recipe
💡 General Rules for Building a Recipe tap to expand ▾
These guidelines help you choose the right materials and keep your glaze balanced.
| Material | Guideline |
|---|---|
| Nepheline Syenite | Preferred source of Na₂O & K₂O — use to keep Soda Ash as low as possible |
| Custer Feldspar | Good for keeping cost low, but avoid if it forces you to use Soda Ash |
| Whiting | Primary source of CaO — use as needed to hit your calcium target |
| ⚠️ Alumina Hydrate | Keep as low as possible — only add if Kaolin alone cannot reach your Al₂O₃ target |
| ⚠️ Soda Ash | Keep as low as possible — causes crawling and is hygroscopic. Use Nepheline Syenite instead when you can |
| Silica | Add to reach your SiO₂ target after other materials are set |
| ✅ Kaolin | At least 2% by weight, preferably at least 10% — keeps glaze suspended and adds Al₂O₃ naturally |
📌 Recipe Strategy tap to expand ▾
🧱
G-200 Feldspar / Neph Sy — supplies K₂O & Na₂O. Adjust so K₂O + Na₂O = 0.3. Use Neph Sy to keep Soda Ash low.
🪨
Kaolin — supplies Al₂O₃. Keep at least 2%, preferably ≥10%.
🔬
Silica — supplies SiO₂. Add last to hit your Si target.
🪨
Whiting — supplies CaO. Primary calcium source.
⚠️
Alumina Hydrate — keep as low as possible. Only add if Kaolin alone can't reach your Al₂O₃ target.
⚠️
Soda Ash — keep as low as possible. Causes crawling. Use Neph Sy instead when you can.
✏️ Your Recipe tap to collapse ▴
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Your Calculated UMF
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📋 What to Adjust
Score
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At a Glance
🎓 Chemistry Story
UMF — What's in This Glaze
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🛒 Shopping List
Materials and studio items to buy. Enter items below, or add materials from a recipe.
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How it works: Check off items as you buy them → tap + Inventory to record grams on hand in your Materials tab.
🎚️ Adjust a Recipe
Load any saved recipe, then use sliders to adjust individual materials. The UMF and Stull chart update live so you can see exactly what each change does to the chemistry.
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Original Glaze
Adjusted Glaze
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Stull Chart
🟠 Starting glaze chemistry · 🔵 Drag to change the chemistry
What Changed
🎨 Add Colorants (optional)
Add colorants to your adjusted base. Each colorant shows what it will do in your current base chemistry.
🧱 Materials
Tap any material to learn what it does and see safety information
📖
Oxide Reference
Study the role, behavior, material sources, and fired effects of the oxides used in ceramic glazes.
ℹ️ How to Use Glaze Lab
Everything you need to know about using this calculator
The Unity Molecular Formula (UMF), also called the Seger formula, is a way of expressing a glaze's chemistry in terms of moles of each oxide, normalized so that the flux oxides (RO group) add up to 1.0. This makes it easy to compare glazes and understand how changing one material affects the whole chemistry. It is the standard method used by ceramic chemists worldwide.
The Stull chart (published by R.T. Stull in 1912) plots a glaze's SiO₂ (Silica) value on the X axis and Al₂O₃ (Alumina) value on the Y axis from the UMF. It divides the space into zones: Underfired (won't melt properly), Matte (low silica, dry surface), Satin Matte (transitional), Glossy (the main working zone), and Runny (too fluid, may run off the pot). Most successful Cone 6 glazes fall in the Glossy zone.
On the Results tab, you'll see your glaze plotted as an orange dot on the Stull chart. Click or drag anywhere on the chart to set a target position (shown as a blue dot). The app will then calculate what changes to make to your recipe to move the glaze toward that target — for example, "Add 8g more Silica" or "Increase EPK Kaolin by 5g". Tap Apply These Changes to update your recipe automatically.
Si:Al Ratio: 8–12 (ideal: 9–10)
SiO₂ (UMF): 3.0–5.0
Al₂O₃ (UMF): 0.3–0.5
CaO (UMF): 0.3–0.7
MgO (UMF): 0.1–0.3
Thermal Expansion: 6–8 × 10⁻⁶/°C
These are guidelines, not strict rules. Many beautiful glazes fall outside these ranges.
SiO₂ (UMF): 3.0–5.0
Al₂O₃ (UMF): 0.3–0.5
CaO (UMF): 0.3–0.7
MgO (UMF): 0.1–0.3
Thermal Expansion: 6–8 × 10⁻⁶/°C
These are guidelines, not strict rules. Many beautiful glazes fall outside these ranges.
RO / R₂O (Fluxes): These oxides help the glaze melt. They sum to 1.0 in the UMF. Examples: CaO (calcium), MgO (magnesium), K₂O (potassium), Na₂O (sodium).
R₂O₃ (Stabilizers): These stabilize the melt and prevent running. Al₂O₃ (alumina) is the most important — it also affects surface texture. B₂O₃ (boron) is a flux at this level.
RO₂ (Glass Formers): SiO₂ (silica) is the main glass former — it makes the glaze glassy, hard, and durable.
R₂O₃ (Stabilizers): These stabilize the melt and prevent running. Al₂O₃ (alumina) is the most important — it also affects surface texture. B₂O₃ (boron) is a flux at this level.
RO₂ (Glass Formers): SiO₂ (silica) is the main glass former — it makes the glaze glassy, hard, and durable.
Always wear a dust mask (N95 or better) when weighing or mixing dry glaze materials. Silica dust is the most serious long-term hazard in ceramics — it can cause silicosis, a permanent lung disease.
Wet-mix when possible — this dramatically reduces airborne dust.
Never dry-sweep — use a wet mop or HEPA vacuum.
Wash hands thoroughly after handling any glaze materials.
Special hazards: Barium carbonate (toxic), manganese dioxide (neurotoxin), cobalt (possible carcinogen), and lithium carbonate require extra precautions. Tap the ⚠️ icon next to any ingredient for specific safety information.
Wet-mix when possible — this dramatically reduces airborne dust.
Never dry-sweep — use a wet mop or HEPA vacuum.
Wash hands thoroughly after handling any glaze materials.
Special hazards: Barium carbonate (toxic), manganese dioxide (neurotoxin), cobalt (possible carcinogen), and lithium carbonate require extra precautions. Tap the ⚠️ icon next to any ingredient for specific safety information.
GlazeIQ uses the Unity Molecular Formula (UMF) calculation method. Thermal expansion uses Eppler & Thiemer weight-basis coefficients. All calculations are performed locally in your browser — no data is sent to any server. Your recipes are saved in your browser's local storage.
Glaze Inspiration Board
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🔧
Fix It Lab
Describe a glaze problem and get ceramic-chemistry-based suggestions for how to fix it — and why each fix works.
🏺 I have a problem with my glaze…
Describe what's going wrong — the more detail the better (cone, atmosphere, clay body, what it looks like).
Common Problems — tap to fill:
📋 Reference Notes
Zinc oxide: It can strongly influence glaze color. In a zinc-free glaze, avoid magnesium oxide unless the stain specifically supports it. Combined zinc in some stains is different from free zinc oxide in the glaze.
Calcium oxide: Ref 9 colors develop best with 12–15% calcium carbonate. Wollastonite can improve uniformity, but its added silica must be accounted for.
Firing: References 2–4 are maximum limits, not guarantees. Schedule, atmosphere, cooling rate, and firing speed can change the resulting color.
Composition key
Al · Aluminum oxideB · Boric oxideCa · Calcium oxideCd · CadmiumCo · Cobalt oxideCr · Chromium oxideFe · Iron oxideMn · Manganese dioxideNi · Nickel oxidePr · PraseodymiumSe · SeleniumSb · Antimony oxideSi · Silicon dioxideSn · Tin dioxideTi · Titanium dioxideV · Vanadium pentoxideZn · Zinc oxideZr · Zirconium dioxide
Mason Color’s recommendations are guidance, not a guarantee of fired results. Test each stain in your own glaze, body, firing cycle, and atmosphere. For safety and handling, use the Safety Data Sheet for the product.
🔺
Triaxial Blend Pyramid Grid
Blend three materials across a 4-step triangular grid. Each cell shows the A/B/C percentages. Upload a photo of your fired test tile for each blend.
🧱 Name Your Three Corner Materials
Corner A — Material 1
A:100 B:0 C:0
Corner B — Material 2
A:0 B:100 C:0
Corner C — Clay Body
A:0 B:0 C:100
🔥 Cone
💨 Atmosphere
🏺 Clay Body
📊 Blend Grid
Tap any cell to add a photo and notes for that test tile
Grid Size:
💡 JPG saves the grid as an image. PDF opens the print dialog — choose “Save as PDF” in your browser.
Saves this triaxial blend (corners A, B, C + all tile photos & notes) to your recipe library.
📐
Stull Chart Grid Explorer
Explore every position on the Stull chart. Tap any grid button to see the full UMF chemistry, then send it to Fill for Chemistry to build a recipe.
🧪 Fixed Base Fluxes (Unity = 1.0)
CaO
0.7
Calcium Oxide
K₂O
0.2
Potassium Oxide
Na₂O
0.1
Sodium Oxide
These three fluxes are constant across the entire grid. Only Al₂O₃ (rows) and SiO₂ (columns) change.
Stull Chart Zones
Al₂O₃ vs SiO₂ GridTap any position to see the full UMF chemistry and send it to Fill for Chemistry
💡 The classic base glaze (position #53) is CaO 0.7 · K₂O 0.2 · Na₂O 0.1 · Al₂O₃ 0.4 · SiO₂ 3.0
⚖️
Specific Gravity Lab
Learn how to measure glaze specific gravity, understand what it tells you, and use Brongniart's Formula to calculate exactly how much dry material and water you need.
Step 1 of 8
1
Let’s Calculate How Thick or Thin Your Glaze Is
We're going to figure out how thick or thin your glaze is — without guessing.
To measure it, we'll fill a container with glaze, weigh it, and do one simple division. That's it!
🎨 Ceramic Colorant Map
Drag the dot to explore. Click a cell to see details and add to batch.
Oxidation firing — electric kilns and gas kilns with full air supply. Colors shown are typical results; actual results vary with base glaze chemistry.
Source: Robin Hopper, The World of Ceramic Colorants, Ceramic Arts Daily © 2016. Colors are approximate — actual results vary with base glaze chemistry, cone, and kiln atmosphere.
🎨 Colorant Reference
Each card shows all results — alone and in combination. Tap any card for full info and use options.
🎨 Colorants & Combinations
Select any card to use the oxide color slider.
🎓
Glaze Chemistry Course
Oxide Mix Test, Melt Test, Line Blends, Exercises, Reports, and Instructor resources.
🔬
Oxide Mix Test
Enter up to 3 materials and a blend ratio to see the blended oxide chemistry, automatic chemistry flags, and write your own analysis proving your understanding.
① Enter Your Materials & Blend Ratio
Select each material and enter the percentage for that blend point. Percentages must add up to 100.
🧪
Formulation Exercises
One chemistry — ten different recipes. Each exercise shows a different combination of materials that reaches the same target UMF. Swap materials within each exercise to see how the chemistry shifts.
🎯 The Target Chemistry
This is a classic Cone 6 Oxidation Glossy Base — a workhorse glaze used in teaching because it is stable, food-safe, and sits in the middle of the Stull chart gloss zone. Every recipe below is a different path to the same destination.
Si:Al = 6.9 · Expansion ≈ 65 · Stull zone: Gloss
📋 Instructor Goals for This Exercise
Working through these ten variations builds the ability to:
- Identify which materials supply which oxides and understand why no two materials are interchangeable without chemistry consequences.
- Recognize that the same UMF target can be reached many ways — the material choice affects cost, surface texture, suspension, and firing behavior even when the chemistry is identical.
- Practice material substitution: swapping one feldspar for another, replacing whiting with wollastonite, or switching kaolin for ball clay — and predicting the chemistry shift before firing.
- Understand the role of boron (frits) as a low-temperature flux and how it changes the melt profile.
- Connect the Stull chart position to the expected surface quality of the fired glaze.
Choose a variation:
📄
Reports Lab
Save PDFs from any section, then compile them into a single submission report.
🔥
Materials Melt Test
Document how each material looks, feels, and melts at each firing temperature. Fire to Cone 018, 05, 3, 6, and 10.
📌 Assignment Brief
Fire each material to cone 018, 05, 3, 6, and 10 (5 sets per group). Number each test clearly with ceramic marking oxide or black underglaze. Use a fettling knife to scoop dry material into the recess in each tile. Document how each material feels and looks before firing and at each temperature. Also wet the material slightly to see how water changes the feel.
⚠️ Marking Slip Recipe
50% Red Iron Oxide + 50% Manganese Dioxide — thin with water so it paints like ink. Wipe your tool clean between each material to eliminate cross-contamination.
🏷️ Example Tile Grid (Reference)
This is what a completed tile set looks like. Your grid below mirrors this layout.
📷 Place example photo here — drag & drop or click to upload
Unfired
C018
C05
C3
C6
C10
Tile 1
Tile 2
Tile 3
Tile 4
Tile 5
Tile 6
🔥 Melt Test Grid
📊
Line Blends
Select a group, document each tile across 3 cone temperatures, upload photos, and write your analysis.
🎓
Instructor Dashboard
Manage group assignments for Line Blends. Edit material names, check inventory status, and generate a materials ordering list.
👥 Group Assignments
Edit material names for each group. 🟢 = In Stock (from your Materials inventory). Click any field to edit.
🧑🎓 Student Roster
Upload a CSV or tab-separated file with name and email columns. Existing assignments are kept when the same email is uploaded again.
👤
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