The discovery of a cracked or broken kamado deflector is a situation that worries many owners of ceramic barbecues. When a crack appears on a cooking stone or when a deflector separates into several pieces, the first reaction is often to think that it is a manufacturing defect. However, in the world of kamados, wood-fired ovens and equipment using refractory materials, the reality is generally more complex.
At COEO, we regularly receive questions regarding the cracks observed on the ceramic deflectors used for indirect cooking, smoking, low-temperature cooking, or making pizzas. After several years of experience with kamado users, we find that this phenomenon is well known in the field of refractory materials and does not necessarily indicate a manufacturing anomaly.
1. Cracked deflector: is it serious?
2. The most common causes
3. When should it be replaced?
4. How to avoid breakage?
5. Tips to extend its lifespan
6. Frequently asked questions
WHY ARE KAMADO DEFLECTORS MADE OF REFRACTORY CERAMIC?
Refractory ceramic is used because it has an exceptional ability to absorb, store, and then release heat in a gradual and uniform manner. It is precisely this characteristic that allows for consistent indirect cooking, controlled smoking, and pizzas benefiting from an even heat distribution.
When a deflector is installed in a kamado, it acts as a thermal barrier between the fire and the food. This function is essential for transforming a barbecue into a true outdoor oven capable of performing both long cooks lasting several hours and high-temperature cooking.
However, this heat resistance does not mean that the ceramic is indestructible. Like all refractory materials used in professional ovens, chimneys, pizza ovens, or high-performance cooking devices, ceramic remains subject to particularly significant mechanical and thermal stresses.
IT IS NOT THE TEMPERATURE THAT BREAKS THE CERAMIC BUT THE THERMAL STRESSES
One of the most widespread misconceptions is to think that a deflector simply breaks because it has been exposed to too high a temperature.
In reality, a quality deflector is designed to withstand temperatures far exceeding those encountered during the majority of cooking done in a kamado. The real risk factor is generally the temperature differential to which the piece is exposed.
Certain areas of the deflector can heat up quickly while others remain relatively cool. Meanwhile, some parts of the material expand more quickly than others. This difference in behaviour gradually generates internal tensions known as differential thermal stresses.
After several cycles of heating and cooling, these stresses can cause the appearance of micro-cracks invisible to the naked eye that sometimes end up joining together to form a larger crack.
WHY CAN A DEFLECTOR BREAK ON FIRST USE?
This situation is often difficult for users to understand.
In some cases, a part may have a micro-crack that is completely invisible resulting from a shock sustained during transport, storage, or handling. This structural weakness only reveals itself when the deflector is subjected to its first temperature rise.
This phenomenon is known in all industries using refractory materials. It explains why a part that appears perfectly intact before use may show a crack after its first heating cycle without any apparent defect being observable before use.
HUMIDITY IS OFTEN UNDER-ESTIMATED
Refractory ceramics naturally have a certain porosity. Even when a kamado is protected by a cover, ambient humidity can be gradually absorbed by the accessories stored inside.
At the moment of ignition, this humidity turns into steam. The change of state causes a significant increase in the volume occupied by the water, generating additional stresses in the structure of the ceramic.
It is particularly for this reason that it is often recommended to carry out a gradual temperature rise after a long period of disuse or after several weeks spent in a humid environment.
A CRACK DOES NOT ALWAYS INDICATE THE END OF LIFE OF THE DEFLECTOR
The appearance of a crack may be visually impressive, but it does not necessarily mean that the deflector needs to be replaced immediately.
Like professional pizza stones, refractory oven bricks or certain elements of industrial hearths, many deflectors continue to function properly despite the presence of one or more cracks.
When the stability of the piece is maintained and the deflector remains correctly positioned on its support, cooking performance can remain very close to the original for an extended period.
In contrast, when a complete break occurs or when several pieces become unstable, replacement is generally the most reasonable solution to maintain even heat distribution.
IMPACT OF A CRACK ON PERFORMANCE
| Situation | Consequence |
|---|---|
| Microcrack | No notable impact |
| Through crack | Impact generally limited |
| Stone broken in two | Partially reduced performance |
| Stone broken into several pieces | Replacement recommended |
Many users continue to use a cracked deflector for several seasons without noticing a major difference during cooking.
HOW TO INCREASE THE LIFESPAN OF A KAMADO DEFLECTOR?
Experience shows that the lifespan of a deflector depends more on its use and storage than on its actual age.
A gradual increase in temperature, storage in a dry environment, the absence of shocks during handling, and correct installation on its support generally help to significantly reduce the risk of cracking.
These few simple precautions often allow a deflector to function for many seasons even when used regularly for slow cooking, smoking, or high-temperature pizzas.
THE DEFLECTORS FOR KAMADO OFFERED BY COEO
COEO offers a complete range of deflectors for kamado suitable for different models and various cooking diameters. These accessories have been selected for their ability to distribute heat evenly while providing excellent thermal inertia suited to the requirements of indirect cooking.
Whether the goal is to achieve low-temperature cooking for several hours, to smoke large cuts of meat, to bake artisan bread, or to use the kamado as a true pizza oven, choosing a suitable deflector is one of the keys to success.
The entire range of COEO deflectors is available here
CONCLUSION
A crack or breakage of a kamado deflector is not automatically synonymous with a manufacturing defect. Refractory materials are subjected to considerable thermal stresses that can, over time or under certain specific circumstances, lead to the appearance of microcracks and then visible cracks. Humidity, mechanical shocks, temperature differences, and the handling history of the piece often play a much more significant role than the cooking temperature itself.
For users wishing to extend the lifespan of their indirect cooking accessories, gradual use and proper storage remain the best practices to adopt.
FAQ DEFLECTORS FOR KAMADO COEO
WHAT IS A DEFLECTOR FOR KAMADO?
A deflector for a kamado is a stone or a refractory ceramic plate placed between the firebox and the food to block the direct radiation of the embers and transform the barbecue into a true convection oven. This accessory is essential for indirect cooking, smoking, low-temperature cooking known as "Low & Slow", roasting, artisan breads, and pizzas.
WHY USE A DEFLECTOR IN A KAMADO?
The deflector allows heat to be distributed evenly throughout the cooking chamber. Thanks to this indirect heat diffusion, food cooks more evenly without being directly exposed to flames or embers. This technique is particularly appreciated for long cooking of meats, fish, or poultry as well as for making pizzas and pastries.
CAN A DEFLECTOR CRACK?
Yes. Like all refractory ceramics used in kamados, pizza ovens, or wood-fired ovens, a deflector can develop cracks over time due to repeated thermal stresses. This phenomenon is known throughout the refractory materials industry.
WHY HAS MY DEFLECTOR CRACKED OR BROKEN?
A crack can be caused by the accumulation of thermal stresses related to temperature rises and successive coolings. An invisible micro-crack, handling shock, the presence of moisture in the ceramic, or a significant temperature difference between different areas of the stone can also promote the appearance of a crack or break.
IS A CRACK ALWAYS A MANUFACTURING DEFECT?
No. In the majority of cases observed on refractory ceramics, cracks result from a natural phenomenon related to the use and aging of the material. The presence of a crack alone does not allow for a conclusion of a manufacturing defect.
CAN WE CONTINUE TO USE A CRACKED DEFLECTOR?
In many cases, yes. A slight crack generally does not immediately affect cooking performance. Many users continue to use their deflector for a long time despite the presence of a crack. However, when a complete break compromises the stability of the piece, replacement is recommended.
IS A CRACKED DEFLECTOR DANGEROUS?
No. A crack or even a break in the deflector does not affect the safety of the kamado, the combustion of the charcoal, or the overall structure of the barbecue. The main impact concerns the quality of indirect cooking when the piece becomes unstable or no longer properly fulfills its role as a heat diffuser.
CAN MOISTURE WEAKEN A DEFLECTOR?
Yes. Refractory ceramic is naturally porous and can absorb a certain amount of moisture. During heating, this moisture turns into steam and generates additional stresses that may accelerate the appearance of cracks.
HOW TO INCREASE THE LIFESPAN OF A DEFLECTOR?
The best way to preserve a deflector is to avoid mechanical shocks, to carry out gradual temperature increases when possible, to store the accessories in a dry environment, and to regularly check their proper positioning in the kamado.
CAN A DEFLECTOR BE USED AS A PIZZA STONE?
Some COEO models have been designed to ensure both functions. The references C-A-PSQM Ø30 cm, C-A-PSQL Ø36 cm and C-A-PSQL-W Ø36 cm can be used for both indirect cooking and for making pizzas, bread and pastries.
WHAT IS THE DIFFERENCE BETWEEN A CLASSIC DEFLECTOR AND THE SPLIT & MIX SYSTEM?
A classic deflector creates a single zone of indirect cooking. The Split & Mix system allows for the creation of multiple cooking zones within the same kamado to simultaneously combine direct and indirect cooking. This configuration offers more flexibility for complex cooking.
WHAT IS THE SPLIT & MIX QUATRO MEDIUM?
The Split & Mix QUATRO Medium is a multi-level cooking system consisting of two half-grids made of stainless steel, a circular deflector made of black enamelled ceramic, and a stainless steel support. With dimensions of 35 x 35 x 12.5 cm, it allows for varying cooking configurations and optimises the performance of the QUATRO Medium.
WHAT IS THE SPLIT & MIX QUATRO LARGE?
The Split & Mix QUATRO Large is an advanced multi-zone cooking system comprising two half-moon grids made of 304L stainless steel, two half-deflectors made of black enamelled ceramic, a 304L stainless steel support, and a 304L stainless steel star. Thanks to its two deflecting half-moons, it becomes possible to cook simultaneously on multiple levels and at different temperatures in the same kamado.
ARE COEO DEFLECTORS MADE OF THICK CERAMIC?
Yes. COEO deflectors use thick refractory ceramic ensuring excellent thermal inertia and homogeneous heat distribution. The enamelled models also facilitate maintenance and cleaning after use.
WHICH DEFLECTOR TO CHOOSE FOR YOUR KAMADO?
| Reference | Dimensions | Compatibility |
|---|---|---|
| C-A-DQM | Ø 25 cm - thickness 2cm | QUATRO M and replacement of the stone of the Split & Mix QUATRO Medium |
| C-A-PSQM | Ø 30 cm - thickness 2cm | QUATRO M, QUATRO L |
| C-A-PSQL | Ø 36 cm - thickness 2cm | QUATRO L |
| C-A-PSQL-W | Ø 36 cm - thickness 1cm | QUATRO L |
| C-A-SMQM (Split & Mix M) | 35 x 35 cm | QUATRO Medium |
C-A-SMQL (Split & Mix L) | 46.8 x 46.8 cm | QUATRO Large |
WHERE TO BUY A REPLACEMENT DEFLECTOR FOR KAMADO?
All COEO deflectors, pizza stones and Split & Mix systems are available on the online shop.
IN SUMMARY
Kamado deflectors are essential accessories for successful indirect cooking, smoking, and pizzas. Like all refractory materials, they may show cracks due to thermal stress without necessarily indicating a manufacturing defect. COEO solutions, whether traditional ceramic stones or Split & Mix systems for QUATRO Medium and QUATRO Large, have been designed to provide optimal heat distribution and great cooking versatility.
ADVANTAGES AND DISADVANTAGES OF DEFLECTORS AND ENAMELLED STONES FOR KAMADO
Deflectors and enamelled stones are increasingly appealing to kamado users due to their ease of maintenance and aesthetic appearance. At COEO, the enamelled models are designed to provide excellent heat distribution while facilitating everyday use.
THE ADVANTAGES OF A DEFLECTOR OR AN ENAMELLED STONE
Much easier cleaning
One of the main advantages of enamel lies in its vitrified surface, which limits the adherence of fats, cooking juices, and food residues. Deposits are removed more easily than with raw ceramic or untreated refractory stone.
Better protection against moisture
Enamel forms a protective layer that significantly reduces the natural porosity of the ceramic. The accessory therefore absorbs less moisture when stored in the kamado or in an outdoor environment.
Fewer stains and dirt
Smoke, grease splashes, and cooking residues tend to remain on the surface more. The overall appearance of the deflector generally remains cleaner over time.
Excellent thermal inertia
The application of enamel does not alter the thermal properties of the ceramic. The deflector continues to absorb, store, and distribute heat evenly for indirect cooking, smoking, and pizzas.
Superior aesthetic durability
Enamelled models often retain a more appealing visual appearance after several seasons of use, especially when fatty cooking or frequent smoking is carried out.
THE DISADVANTAGES OF AN ENAMELLED DEFLECTOR OR STONE
Sensitivity to shocks
Enamel is extremely hard but relatively fragile against impacts. A shock with a metal utensil, a stainless steel grid, or a fall can cause a localized chip in the enamel.
Risk of aesthetic crazing
After numerous heating and cooling cycles, fine surface microcracks known as "crazing" may appear in the enamel layer. This phenomenon is generally only aesthetic and does not affect cooking performance.
Repairs impossible
Unlike some metal surfaces that can be locally repaired, a chip in enamel generally cannot be repaired invisibly and durably.
Sometimes higher price
The enamelling process adds an additional manufacturing step that can result in a slightly higher cost than that of an unglazed refractory stone.
SHOULD YOU CHOOSE AN ENAMELLED OR UNENAMELLED DEFLECTOR?
| Criterion | Enamelled deflector | Unenamelled deflector |
|---|---|---|
| Cleaning | Excellent | Good |
| Moisture absorption | Very low | More significant |
| Thermal resistance | Excellent | Excellent |
| Shock resistance | Average | Good |
| Aesthetic aspect | Very rewarding | More rustic |
| Maintenance | Very easy | More demanding |
| Pizza use | Excellent | Excellent |
| Indirect cooking | Excellent | Excellent |
OUR OPINION COEO
For a user primarily seeking ease of maintenance, better moisture resistance, and a more qualitative appearance over time, deflectors and enamelled stones often represent the best choice.
For a user prioritising mechanical robustness and accepting a more technical appearance, a classic refractory stone remains an excellent solution.
In both cases, the performance of indirect cooking, smoking, low-temperature cooking, and pizza cooking remains excellent when the product is used under the intended conditions.