Why Is My Ceramic Glaze Crazing? How to Fix and Prevent It
Crazing is not a firing mistake. It is a thermal expansion mismatch between your glaze and the clay body underneath it.
That fine web of cracks across your glaze surface has nothing to do with underfiring or cooling too fast. The glaze simply shrinks more than the clay during cooling, and the tension creates the crackle pattern you see.
This guide covers every cause of crazing, three proven methods to fix it permanently, and the materials science that explains why it happens. You will learn how to test your clay and glaze combination before firing, how to adjust your glaze recipe to eliminate the mismatch, and when crazing is actually a desired decorative effect rather than a defect.
By the Numbers
Glaze Crazing — What the Research Shows
Sources: Digitalfire Reference Library, Ceramic Materials Database, Orton Foundation
What Is Glaze Crazing? The Materials Science Behind the Cracks
Crazing is a network of fine cracks that forms in the glaze surface when the glaze shrinks more than the clay body during cooling after firing. The cracks appear because the glaze is under tension. It stretched to fit the clay at high temperature, then contracted too much as the kiln cooled.
This is a coefficient of thermal expansion (COE) problem. Every ceramic material expands when heated and contracts when cooled. The COE measures how much a material changes size per degree of temperature change. Glaze with a higher COE than the clay body will craze.
The mismatch can be as small as 0.5% difference in expansion rates to produce visible cracking. According to the Digitalfire Reference Library by Tony Hansen, most functional stoneware clay bodies have a COE between 6.5 and 7.5 (×10⁻⁶/°C). A glaze with a COE of 8.0 on a body measuring 7.0 will craze reliably.
Crazing is not always immediate. Delayed crazing can appear days, weeks, or even months after firing. This happens when the fired clay body absorbs moisture from the air and swells slightly. The glaze cannot stretch to accommodate the swelling, so it cracks.
In plain terms: the glaze is like a tight shirt on a person who keeps growing. Eventually the fabric tears. Your glaze tears into the crackle pattern called crazing.
Not all crackle patterns are defects. In raku pottery and certain Chinese celadon traditions, intentional crackle is prized as a decorative effect. The difference is control. Intentional crackle is planned. Unwanted crazing means your materials do not match.
What Causes Ceramic Glaze to Craze? 5 Root Causes
1. Glaze COE Is Higher Than the Clay Body COE
This is the primary cause of crazing. The glaze formula contains too much flux, especially high-expansion fluxes like sodium and potassium from feldspars. These oxides increase the thermal expansion of the melted glass.
Each flux oxide has a different expansion contribution. Sodium oxide (Na₂O) has the highest expansion factor at approximately 4.16. Potassium oxide (K₂O) follows at 3.90. Calcium oxide (CaO) is much lower at 1.63.
A glaze heavy in soda feldspar like Minspar 200 will expand significantly more than one using whiting (calcium carbonate) as the primary flux. The mechanism is straightforward. Sodium ions are large and weakly bonded in the glass network, allowing more movement during temperature changes.
This only occurs when the total flux balance pushes the glaze COE above the body COE, typically by 0.5 units or more. If the difference is smaller, the glaze may survive without crazing.
2. Insufficient Silica in the Glaze Formula
Silica (SiO₂) is the glass former in glaze. It also reduces thermal expansion because silica-rich glasses have lower COE values. A glaze with low silica content relative to its flux content will have higher expansion.
Adding 2-5% extra silica to a crazing cone 6 glaze often resolves the problem entirely. According to Mastering Cone 6 Glazes by John Hesselberth and Ron Roy, increasing silica by 3% of the total glaze batch weight reduces COE by approximately 0.3-0.5 units.
This happens because silica tetrahedra link together into a tighter network with less free volume for thermal movement. The condition for success is that the glaze still melts completely at your firing temperature with the added silica. Too much silica and the glaze becomes underfired and matte.
If you add silica and the glaze no longer melts to a smooth surface at cone 6 (2232°F / 1222°C), the result is a dry, pebbled surface. Fix it by adding a small amount of additional flux like whiting (1-2%) to compensate.
3. Clay Body Absorbs Moisture After Firing
Delayed crazing happens when a fired clay body has an absorption rate above 1-2%. Water from the atmosphere or from use enters the porous clay and causes it to swell. The glaze, being a rigid glass, cannot swell with it and develops cracks under the new tension.
This is common with earthenware bodies fired to cone 06-04 (1828-1940°F / 998-1060°C) where absorption rates are 5-12%. Even some cone 6 stoneware bodies with absorption above 2% will show delayed crazing over months of use.
To test your clay body absorption rate, weigh a fired unglazed test tile, boil it in water for 2 hours, then weigh it again. The percentage weight increase is the absorption rate. Bodies over 1% absorption risk delayed crazing even with a properly matched glaze.
Vitrification is the solution. A clay body that is fully vitrified, with absorption under 1%, will not swell after firing and cannot cause delayed crazing regardless of environmental humidity.
4. Fast Cooling Through the Quartz Inversion Zone
Quartz crystals in the clay body undergo a sudden volume change at 1063°F (573°C) during cooling. This is the quartz inversion. If the kiln cools too fast through this temperature zone, the rapid contraction of quartz particles can create micro-stress that contributes to crazing.
This is a secondary cause, not a primary one. A well-matched glaze and body will survive fast cooling without crazing. But a marginal match can be pushed into failure by thermal shock from rapid cooling.
The failure mode appears as more severe crazing on thinner walls and rims where cooling is fastest. The fix is slowing the cooling rate to no more than 150°F (83°C) per hour between 1100°F (593°C) and 900°F (482°C).
5. Glaze Application Thickness Is Too High
Thicker glaze layers experience greater stress during cooling because the outer surface of the glaze cools and contracts before the inner portion in contact with the clay. This differential cooling within the glaze layer itself adds to the overall tension.
A glaze applied at 2mm thickness (about the thickness of two credit cards) is ideal for most dipping glazes. Glaze applied at 3mm or thicker is significantly more prone to crazing, even on a reasonably matched clay body.
Push a needle tool through wet glaze to the clay surface to check thickness before firing. Two millimeters is your target for most functional ware applications.
Myth vs Fact
Glaze Crazing — Common Myths Debunked
Separating fact from fiction on the most common crazing misconceptions
✗ Myth
Crazing means the kiln was fired too hot or cooled too fast.
✓ Fact
Crazing is a chemistry problem, not a firing schedule problem. The glaze formula and clay body have mismatched thermal expansion rates. A properly matched glaze will not craze even with fast cooling. A poorly matched one will craze with the gentlest firing schedule.
✗ Myth
A crazed glaze is food-safe if you cannot feel the cracks with your fingernail.
✓ Fact
Any crack in a food-contact surface is a bacteria trap. The FDA classifies severely crazed ware as unsanitary because bacteria can lodge in microscopic cracks that cleaning cannot reach. Even fine crazing lines create capillary action that pulls in food particles and moisture.
✗ Myth
Commercial brushing glazes never craze because manufacturers test them.
✓ Fact
Manufacturers test on their own recommended clay bodies. Using a different clay body, firing to a slightly different cone, or applying glaze thicker than recommended can all cause crazing even with premium commercial glazes. Always test your specific clay and glaze combination before producing a full batch.
✗ Myth
You can fix crazing by refiring the pot to a higher temperature.
✓ Fact
Refiring does not change the COE of either the glaze or the clay body. It may temporarily heal the cracks by re-melting the glaze, but the same expansion mismatch remains. The crazing will return, often worse than before, because the second firing adds more heat history stress to the clay.
✗ Myth
Adding more flux to the glaze will fix crazing.
✓ Fact
Fluxes increase thermal expansion in almost every case. Adding more flux makes crazing worse, not better. The correct fix is adding silica or reducing high-expansion fluxes like sodium and potassium in favor of lower-expansion fluxes like calcium, magnesium, or lithium.
How to Test If Your Glaze Will Craze Before You Fire a Full Kiln Load
Make Glaze Fit Test Bars
Roll out a slab of your clay body about 5mm thick. Cut strips roughly 100mm long and 20mm wide. Bisque fire these strips to your normal bisque temperature (typically cone 06-04, 1828-1940°F / 998-1060°C).
Apply your glaze to one side of each test bar at your standard application thickness. Fire to your normal glaze temperature. A crazing-resistant glaze will leave the bar flat or with a very slight curve toward the glazed side.
Read the Warp Direction
After firing, the test bar will curl if there is a COE mismatch. If the bar curves with the glazed side on the inside of the curve (concave), the glaze has higher expansion than the body. This glaze will craze.
If the bar curves with the glazed side on the outside (convex), the glaze has lower expansion than the body. This glaze is under compression, which is ideal for functional ware and will not craze.
Use a 300°F Thermal Shock Test
Heat your glazed test piece in an oven to 300°F (149°C) for 30 minutes. Remove it and immediately plunge it into ice water. A glaze that survives this test without crazing is well-fitted to the clay body and unlikely to craze in normal use.
This test is more aggressive than dishwasher cycles or daily use thermal shocks. According to the Orton Foundation firing standards documentation, glazes that pass this ice-water quench test have a COE mismatch of less than 0.3 units. This is the threshold for durable functional ware.
How to Fix Crazing: 3 Proven Methods
Step-by-Step Guide
How to Fix a Crazing Glaze — Step by Step
4 steps · Each method may require 2-3 test firings to verify results
Add Silica to the Glaze in 2% Increments
Weigh out a 100-gram test batch of your dry glaze. Add 2 grams of 325-mesh silica (2% addition). Mix thoroughly, sieve, and apply to a test tile or test bar. Fire to your normal cone. If crazing persists, try a second test with 5% added silica.
Swap High-Expansion Fluxes for Low-Expansion Alternatives
Replace some or all of your soda feldspar (high Na₂O, expansion factor 4.16) with a lithium source like spodumene (Li₂O, expansion factor 1.27). Lithium is the lowest-expansion flux available. Even a 5-10% substitution of spodumene for neph sye or Minspar can reduce glaze COE by 0.5-1.0 units.
Switch to a Lower-Expansion Clay Body
If you are using a pre-made commercial glaze you cannot adjust, change your clay body instead. Test your glaze on several different clay bodies available from your supplier. Some clay bodies, particularly those with high silica and low flux content, have naturally lower COE values closer to 6.0-6.5.
Reduce Glaze Application Thickness
Thinner glaze layers develop less internal stress during cooling. Reduce your dipping time, thin your brushing glaze slightly with water, or switch from pouring to a faster dip. Target 1.5-2mm thickness on bisqueware. Measure with a needle tool through the wet glaze.
For a comprehensive guide on solving every type of glaze surface defect beyond just crazing, our detailed troubleshooting guide covers crawling, pinholing, blistering, and all other common glaze problems with specific recipes and fixes for each defect.
How to Prevent Crazing Before It Starts
Calculate COE Match Before Mixing
Use glaze calculation software like GlazeMaster or HyperGlaze to predict the COE of your glaze recipe. Enter your clay body’s published COE from the manufacturer’s data sheet. Adjust the glaze formula until the predicted COE is 0.3-0.5 units lower than the body COE.
This produces a glaze under slight compression, which is the ideal state for functional ware. A glaze under compression is more chip-resistant and cannot craze because it is being squeezed, not stretched.
The mechanism works because glass is approximately 10 times stronger in compression than in tension. A compressed glaze surface resists both crazing and mechanical damage from utensils and handling.
Use the Same Clay Body Consistently
Every time you change clay bodies, retest every glaze. A cone 6 stoneware from one manufacturer may have a COE of 7.2, while another cone 6 stoneware measures 6.8. That 0.4 unit difference is enough to push a marginal glaze from functional to crazed.
Potters who buy whatever clay is on sale at their local supplier often struggle with intermittent crazing problems that seem random. The problem is not random. It follows the clay lot they used that week.
Ensure Full Vitrification of the Clay Body
A clay body with absorption above 1% is not fully vitrified. It will absorb water after firing and can swell enough to craze a previously sound glaze weeks or months later. Fire your clay body to the temperature where it reaches under 1% absorption.
Test this by firing unglazed clay tiles to different cones. Boil each tile for 2 hours, weigh the water gain, and find the cone where absorption drops below 1%. Fire to at least that cone for all functional ware.
Control Cooling Rate Through Quartz Inversion
Program your kiln controller to cool no faster than 150°F (83°C) per hour between 1100°F (593°C) and 900°F (482°C). This gives quartz crystals in the clay time to complete their volume change gradually. The slower cooling reduces stress on the glaze-to-clay interface.
For manual kilns, simply close all peepholes at the end of firing and do not open them until the kiln is below 400°F (204°C). The natural cooling rate of a closed electric kiln is usually gentle enough through the quartz inversion zone.
Glaze Chemistry Adjustments for Specific Crazing Scenarios
Fixing Crazing in a Clear Gloss Glaze at Cone 6
A typical clear gloss cone 6 glaze that crazes often has a formula like: 40% feldspar, 15% silica, 15% whiting, 10% kaolin, 10% frit 3124, and 10% zinc oxide. The high feldspar content drives sodium and potassium levels too high for many clay bodies.
To fix this, reduce the feldspar to 30% and increase silica to 20%. Add 5% spodumene for a lithium contribution that lowers COE without sacrificing gloss. The adjusted recipe: 30% Minspar 200, 20% silica (325 mesh), 15% whiting, 10% EPK kaolin, 10% Ferro Frit 3124, 10% zinc oxide, and 5% spodumene.
This recipe change reduces the predicted COE from approximately 7.8 to 7.0. It matches most cone 6 stoneware bodies that measure 6.8-7.2. Test on your specific clay before committing to a large batch.
Fixing Crazing in Matte Glazes at Cone 6
Calcium-magnesium matte glazes craze for a different reason than gloss glazes. During slow cooling, calcium forms anorthite micro-crystals that have different expansion characteristics than the surrounding glass matrix. The crystal-to-glass interface within the glaze becomes a stress point.
The fix is adding 2-4% lithium carbonate (not spodumene; use the pure carbonate for precise control) to the recipe. Lithium enters the glass phase and lowers its COE without interfering with the calcium matte crystal formation. This addresses the glass-phase expansion while preserving the matte surface texture.
This only works when the matte is a true calcium-saturated formula, not an underfired or alumina-deficient matte. If your matte comes from underfiring rather than crystal formation, the crazing fix is different: increase firing temperature or add more flux.
Quick Reference
Glaze Crazing — Key Terms Explained
Quick reference for the terms used throughout this guide
A measure of how much a material expands when heated measured in units of 10⁻⁶/°C. Glaze COE must be equal to or slightly lower than the clay body COE to prevent crazing.
An oxide that lowers the melting temperature of silica in glaze. Common ceramic fluxes include sodium, potassium, calcium, magnesium, lithium, and zinc. Each has a different effect on glaze expansion.
The sudden volume change of quartz crystals at 1063°F (573°C). During cooling, quartz contracts abruptly at this temperature. Fast cooling through inversion can contribute to crazing and dunting.
The process where clay becomes non-porous and glass-like during firing. A fully vitrified clay body has under 1% absorption and will not absorb water that can cause delayed crazing.
A lithium aluminum silicate mineral used as a low-expansion flux in glaze. Contains approximately 8% Li₂O. Lithium has the lowest expansion factor (1.27) of all common ceramic fluxes.
A group of aluminum silicate minerals containing sodium, potassium, and/or calcium. The primary flux source in most stoneware glazes. Soda feldspar contributes more to crazing than potash feldspar due to sodium’s higher expansion factor.
A glaze with a COE slightly lower than the clay body so it is squeezed by the body during cooling. Compression makes glaze stronger and more chip-resistant. This is the ideal state for functional pottery.
Crazing that appears days to months after firing. Caused when the fired clay body absorbs atmospheric moisture and swells, placing the rigid glaze under tension it was not under immediately after cooling.
When Is Crazing Acceptable? Intentional Crackle Glaze
Not all crazing is a defect. Intentional crackle glaze is a traditional decorative technique in several ceramic traditions. Chinese Guan and Ge ware from the Song Dynasty deliberately produced crackle patterns that were stained with ink or tea to highlight the network of lines.
Raku pottery, fired to approximately 1850°F (1010°C) and removed from the kiln while glowing hot, produces crackle as a standard feature. The thermal shock of post-firing reduction in combustible materials creates deliberate crazing that defines the raku aesthetic.
For intentional crackle on functional ware, there are important food safety conditions. Only use crackle on the exterior of pots that will hold food on the interior. Never use crackle glaze on the food-contact surface of plates, bowls, or mugs.
If you must have crackle on a food surface, seal the cracks with a food-safe penetrating sealer, and understand that this is a compromise, not a permanent solution. The most honest approach is keeping crackle decorative, not functional.
How Crazing Affects Glaze Color and Appearance
Crazing changes how light reflects from the glaze surface. The crack network scatters light differently than a smooth glass surface. Colors can appear slightly duller or cloudier on crazed glazes because the micro-cracks diffuse reflected light in multiple directions.
On some iron-bearing glazes like celadons and tenmokus, crazing lines can actually enhance depth by creating a subtle secondary pattern beneath the main color. This is why some potters intentionally push their celadon glazes toward light crazing.
For precise color matching across a line of dinnerware, crazing is a consistency problem. Getting repeatable color results from your glazes becomes harder when some pieces craze and others do not. The surface texture difference registers to the eye as a color shift even when the pigment concentration is identical.
Buying Guide
Ask Yourself These Questions Before You Fix Crazing
Tap each card to reveal what your answer means for your approach to fixing the problem.
Crazing vs Shivering: Opposite Failures, Related Cause
Crazing and shivering are opposite ends of the same problem. Crazing means the glaze COE is too high relative to the body. Shivering means the glaze COE is too low, placing the glaze under extreme compression until it pops off the clay surface in sharp flakes.
The same glaze fit test bar reveals both problems. A bar curved toward the glazed side means the glaze will craze. A bar curved strongly away from the glazed side means the glaze may shiver, especially on sharp rims and edges.
The ideal test bar is nearly flat, with a very slight curve away from the glazed side. This shows the glaze is under mild compression, which is the durable, non-crazing, non-shivering sweet spot for all functional ceramic ware.
How Application Method Affects Crazing Tendency
The way you apply glaze changes the fired thickness and the stress distribution during cooling. Dipping produces the most uniform coating and the most predictable crazing behavior. Brushing often leaves uneven thickness that creates localized stress concentrations where crazing starts.
Spraying glaze onto bisqueware gives you the finest control over application thickness, allowing you to build thin, even coats that minimize internal stress. Potters who struggle with crazing on dipped ware sometimes solve the problem entirely by switching to spray application at 1.5mm thickness.
Pouring glaze over a piece creates the greatest thickness variation. Poured interiors tend to pool thicker at the bottom, and that thicker area is where crazing first appears. If pouring is your only application method, pay extra attention to draining time and glaze viscosity.
For consistent dipping results, a glaze hydrometer keeps your specific gravity at 1.45-1.50 for most commercial dipping glazes. Thicker glaze from evaporation increases both application thickness and crazing risk.
Studio Conditions That Worsen Crazing
Firing Too Fast in the Last 200°F of the Cycle
A fast final ramp to temperature does not give glaze sufficient time to fully melt, flow, and bond to the clay surface. The result is a glaze with residual internal stress from incomplete melting. This combines with COE mismatch to produce more severe crazing.
Program a 10-15 minute hold at peak temperature for every glaze firing. The hold allows the glaze to reach full maturity and release internal stresses that accumulated during the rapid heating phase.
Opening the Kiln Too Early
Opening peepholes or cracking the lid above 400°F (204°C) exposes the cooling ware to room-temperature air. The thermal shock adds tension to the glaze surface right at the temperature range where the glaze is most brittle. Even a well-fitted glaze can craze from this mistreatment.
Wait until the kiln reads below 350°F (177°C) before opening any peephole. Wait until below 200°F (93°C) before opening the lid more than a crack. Patience during cooling prevents more crazing than any glaze chemistry adjustment.
Inconsistent Bisque Firing Temperature
Bisque firing to different cones changes the porosity and absorption of the clay body at the time of glazing. A body bisqued to cone 04 (1940°F / 1060°C) is harder and less absorbent than one bisqued to cone 06 (1828°F / 998°C). Glaze applied to the harder bisque sits more on the surface and builds thickness differently.
Standardize your bisque temperature. Most studio potters bisque to cone 04 and glaze fire to cone 6. This consistency removes one more variable from the crazing equation.
Frequently Asked Questions About Glaze Crazing
Can I still sell pottery with crazed glaze?
Quick Answer: For decorative or sculptural work, yes. For functional ware that contacts food or liquid, no. Crazed food surfaces are a health code concern because bacteria lodge in the cracks. Most craft fair juries and wholesale buyers will reject crazed functional pieces.
Selling crazed functional ware opens you to liability if a customer gets sick from unsanitary conditions in the cracks. Many potters disclose crazing as an aesthetic feature and sell the pieces as decorative only. This is an honest workaround, but it limits your market.
Your best long-term strategy is fixing the crazing before it limits what you can sell and to whom.
Why did my glaze craze on one clay body but not another?
Quick Answer: Different clay bodies have different COE values. A glaze that fits a clay body with COE 7.2 may craze on one with COE 6.5 because the gap between glaze and body expansion is now larger.
Clay body COE varies with silica content, flux content, and the specific clay minerals used in the body recipe. Two different cone 6 stoneware bodies from different manufacturers can differ by 0.5-1.0 COE units. That is enough to flip a glaze from durable to crazed.
Always test every glaze on every new clay body you try, even if the clay body fires to the same cone and looks similar to your previous clay.
Can I repair crazed pottery after it has been fired?
Quick Answer: There is no permanent repair for crazed pottery. Refiring temporarily heals the cracks by re-melting the glaze, but the same COE mismatch causes the crazing to return.
Some potters apply a thin overglaze or clear coat to fill crazing lines, but this is a cosmetic cover, not a structural fix. The underlying tension between glaze and body remains.
The only permanent solution is changing the glaze chemistry or the clay body so the next batch does not craze. Already-crazed pieces cannot be economically salvaged to food-safe condition.
What happens if I use a cone 10 glaze in a cone 6 kiln?
Quick Answer: A cone 10 glaze fired to cone 6 will be underfired, producing a dry, chalky, under-melted surface. The glaze ingredients never reached their melting range. The underfired surface may also craze because the glaze did not fully bond to the clay.
Cone 10 glazes rely on higher temperatures (2381°F / 1305°C) to melt silica and alumina ratios that remain refractory at cone 6 (2232°F / 1222°C). The 400°F difference means the glaze never fully matured. Crazing is just one of several problems you will see.
Is crazing more common with matte glazes than gloss glazes?
Quick Answer: Yes. Matte glazes craze more often than gloss glazes because the crystal structures that create the matte surface (calcium anorthite, magnesium silicate, zinc silicate) have different expansion rates than the surrounding glass.
The crystal-to-glass boundaries within a matte glaze are internal stress points where crazing can initiate. Gloss glazes are homogeneous glass with no internal crystal boundaries, so stress distributes more evenly.
Calcium mattes are particularly prone to crazing because anorthite crystals grow during cooling and create localized stress in the glaze film. Adding 2-4% lithium to matte glazes helps match the glass phase COE to the crystal phase COE.
How do I know if crazing is from my glaze or my clay body?
Quick Answer: Test the same glaze on three different clay bodies. If it crazes on all three, the glaze is the problem. If it crazes on only one body, that specific clay body is the problem.
Also test your clay body absorption rate. If absorption is above 1%, the body contributes to crazing regardless of the glaze, because post-firing moisture swelling will eventually crack any rigid glaze.
These two tests together isolate whether you need to fix your glaze, your clay, or both.
Does glaze color affect crazing tendency?
Quick Answer: Colorant oxides can slightly change glaze expansion. Cobalt oxide (0.5-2%) tends to reduce COE slightly. Copper oxide can increase COE. Iron oxide has minimal effect at typical 2-8% concentrations.
The effect is usually small compared to the major flux and silica balance in the recipe. But if a glaze is right on the edge of crazing, switching from a clear version to a heavily colored version might push it over the edge in either direction.
Test each color variant separately, especially for production lines where consistency across colors matters.
Can crazing develop from microwave use?
Quick Answer: Yes. Microwave heating is uneven and rapid, creating localized thermal stress that can craze a marginal glaze. The water in food heats first, transferring heat unevenly through the ceramic wall.
A glaze that survives dishwasher cycles may still craze from repeated microwave use because the heating rate is more aggressive and the temperature gradient across the piece is steeper.
If your functional ware is microwave-safe on the label, you must test for microwave-induced crazing by heating water in the piece for 2 minutes, then plunging it into cold water. Repeat 5 times. This simulates worst-case microwave use.
Conclusion
Crazing is a solvable materials science problem, not a mysterious kiln gremlin. The fix is matching your glaze COE to your clay body COE through silica additions, flux substitutions, or clay body changes.
Test every glaze and clay combination before producing full batches. Use glaze fit test bars, absorption rate tests, and thermal shock tests to catch problems before they reach your customers or your kitchen cabinet.
For home studio potters making functional ware, the combination of a vitrified cone 6 stoneware body with under 1% absorption and a glaze formula verified through COE calculation software will eliminate crazing permanently. Start with a test tile today.
