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Part of owning a wood fired oven means that you will at times see small cracks in the oven. However, it is perfectly normal to see a few hairline cracks. Let’s explore why these cracks happen and what to do if you notice larger cracks. 

Why do small cracks happen in wood fired ovens?

Small cracks happen in your oven because you’re heating a rigid, ceramic/refractory concrete structure to very high temperatures. These high temperatures create thermal stress in the brickwork/refractory concrete structure. To relieve the stress, the oven forms small cracks, which are usually around 1 mm wide. 

It’s very common to see small cracks that start at the base of the dome and runs up to the keystone, as well as some small cracks around the flue gallery and in the mortar joints of the vent arch. 

What can you do about cracks in your oven?

Small cracking is normal and there’s nothing that you can do to prevent it. What’s important is to understand that they won’t get worse over time. It is very rare, but if you see a larger crack (over 2 mm in width) in your mortar, then it must be repaired. 

Larger cracks usually happen due to the oven being over-fired early in the curing stages. Any cracking in the Perlite render can be covered by the roll-on acrylic coating applied once the oven is fully cured. 

How to properly cure your oven

Keeping your fire low and slow is the best method during the curing process. To properly cure your oven, start a small fire with low flames. Doing this helps the moisture to evaporate gradually. On the first day of the curing process, light a 100°C fire inside your oven for up to three hours. Do this for an entire week before cooking any food in your oven. Over time, you will likely see small cracks forming in the dome or the hearth. This is normal.

Another way to cure your pizza oven is to light coals separately and then place them in the oven. By doing this, the oven will cure gradually from the heat, but won’t have any flames. When you use your oven for the first time, it is important to start slowly. Light a small fire in the oven and then slowly make it larger until the interior oven dome turns black. Seeing this means that the fire has reached 300°C, which is perfect for cooking.

Need help with your pizza oven?

While some pizza ovens may crack more than others, these small and superficial cracks do no structural damage, and your oven will have a long life. If, however, you are concerned about any cracking, you can contact our team for assistance.