Most people recognize the cob oven as an excellent method of cooking pizza. While this is true, there are so many other things that these ovens are capable of, as you will see below.
Cob ovens can dry sand, craft wood, resins, and damp firewood for the next cook-up.
Why use a cob oven for drying?
The cob oven stores heat from a fire that is placed inside the oven chamber, and once the fire is removed, the oven walls then expel that heat back into the oven chamber.
This is mainly used for cooking food. Often there are times when the oven still contains a good amount of heat after all cooking is completed, and this is an opportunity for using the residual heat to dry other items.
Using a cob oven to dry non-edibles.
The residual heat that lingers in a cob oven chamber has many uses once you start to think outside the box. Here are a few ideas to consider.
- Craft wood pieces.
- Craft sand.
- Post-curing resin jewelry.
- Sand for resin granite mixing.
- Damp firewood for the next cook-up.
What kind of craft wood should you dry?
The wood that can be dried in a cob oven is small pieces of craft wood that may still be green from milling. Wood intended to be turned on a wood lathe can also be dried.
How long does it take to dry craft wood in a cob oven?
There are many factors to consider, but the rule of thumb is a minimum of 8hrs for a 1inch thick board of low-medium density wood.
It may take longer depending on your oven and the airflow within your oven.
Dense hardwoods will take days and will not be effective in a cob oven where the heat source is residual and in thermal decay. It can help with removing some of the moisture, however.
What size wood can be dried?
The size of the wood will depend on the oven’s internal chamber. The longer the wood, the more time will be required. The moisture will mostly leave the wood from the end grain, with some also removed from the face or side grain.
Smaller-length pieces offer the best chance of success. The rule to follow here is if the wood is hardwood, then the size of the wood (thickness) needs to be smaller than a softwood.
The hardness of the wood is directly related to how small it needs to be to dry effectively. This will be a trial-and-error process for you and your oven. Every oven will be different, as will the type of wood you work with.
Can the wood be damaged by drying in a cob oven?
Wood can be damaged if the oven is still too hot, and may cause twisting, cupping, and warping.
The method we suggest is to make sure the temperature is under 150F or 65C ish. The thinner the wood pieces, the slower and lower the temp should be.
Traditional kiln drying raises the temperature as the wood dries, but we cannot raise the temps without relighting the fire so more heat can be caught in the oven wall.
How to dry craft sand.
The residual heat from the oven can be a gentle warm airflow that suits drying sand used in craft ideas. This is how to go about it.
- Place sand in a shallow metal tray. make sure the sand it only first finger knuckle deep in the tray.
- Place the tray in the oven with spacers under the tray to help airflow.
- Close the cob oven up and leave for a hour.
- After an hour, remove the tray and stir the sand around then level it back out and place back in the oven.
- Repeat the step above until the sand is completely dry.
- Job done.
How to post cure cast resin objects with a cob oven.
Several types of resins require a post-cure to complete the hardening process.
We suggest reading the material data sheet for your resin and checking the required temperature that should be listed. There may be a broad range to follow, also.
Once you know the temperatures, get to know your oven. At some point, the internal temp of your oven will fall to your required temperature. Before you place your resin object inside, it might be wise to time the oven’s ability to hold that temperature.