For wood to be processed, it usually has to be dry. If you use freshly felled wood, there is a high probability that it will later crack or at least warp. In the following article, we explain when the wood is dry enough to work with and how you can dry it as crack-free as possible. In addition, we explain five methods of how tree grates and sawn timber can be dried gently or quickly.
When Is Wood Dry?
To produce beautiful and permanently crack-free objects from wood, the wood should have a moisture content of no more than 10 to 15 percent.
A rule of thumb states that the wood dries about one centimeter per year on all sides. This formula is only a guide and can vary significantly depending on the type of wood.
In general, it can be said that woods with a low bulk density (e.g., poplar) dry faster than woods with a high density (e.g., oak).
Exceptions in Which Wood Can Be Processed “wet” without Cracking
We personally know two exceptions where the wood does not have to dry for a long time to be processed.
On the one hand, our favorite material, driftwood. You can collect it and process it immediately. If the wood is still wet from the water, you can let it dry directly in the sun or in front of the oven. But that only works with driftwood. This would be fatal for normal, natural wood since freshly felled wood, unlike driftwood, is still full of sap. And this has to come out of the wood so that the wood does not tear later.
The second method is very popular with woodturners – wet turning. With this technique, the bowls are pre-turned, and a large part of the material is removed. But then the blanks have to dry again and be finished. Only the drying time is shortened, and the risk of peel cracking is significantly reduced.
Prepare the Wood to Dry
If it can somehow be done, you should saw open the felled log as much as possible. Cut wood dries better and faster than a complete trunk.
This is because there is more surface to dry, and you take most of the tension out of the wood by sawing it open.
Insofar as appearance does not play a major role when sawing, it is always recommended to cut the wood so that the annual rings are standing in the wood. In the picture, you can see what is meant by standing and lying annual rings.
Boards with standing growth rings will warp significantly less when drying than boards with horizontal grain.
In addition, it is advisable to remove the heart (the middle part of the trunk, where the annual rings arise) or at least split it up. Because in the middle of the trunk, there is the greatest tension.
If you cut your wood open like this, you have already achieved more than half the battle so that your wood can dry crack-free.
Different Ways to Dry Wood Crack-Free
There is no single successful method for drying wood without cracks. This is because every wood is different. It depends on the intended use and the size of the wood, which method is best suited.
That’s why we want to introduce you to several methods of how wood can be dried quickly and without cracks.
Air Dry Wood with End Wood Seal
The gentlest method to dry the cut wood is air drying. This process is hundreds of years old and is still used. The sawn timber is stored as the trunk has grown. Wooden slats are inserted between the planks so that the air can flow around the wood. A covered, airy, and shady place is the first choice as a storage location. But even if the wood storage area has these characteristics, the wood must be prepared accordingly to dry it as crack-free as possible. Experts therefore also seal the front surfaces of the cut goods.
The trunk always loses more moisture at the head ends than at the longitudinal grain when drying wood. This creates tension in the wood, and it starts to crack. This is exactly what is presented with a front-end wood seal by sealing the end wood of the trunk airtight. So before you store the wood, coat the front sides plus about 5 cm of the longitudinal wood with a suitable end wood seal.
But then the wood still has to dry as long as it would without sealing. So the wood seal does not shorten the drying time.
We personally use anchor seal or end-grain wax for our end-grain seals and have had good experiences with them. We would only recommend glue and varnish if there is something old that is left over. Otherwise, it is not worth buying the products, especially for it in terms of price.
The Following Means Are Suitable for Sealing the Wood:
- End grain sealing
- End grain wax
- Anchor seal
- Wax mixture
- Glue (waterproof)
- (old) paint
“Air drying is the gentlest and cheapest method of drying construction timber. But you need a lot of time and storage space for this drying process.”
Quickly Dry Wood with The Microwave
Unfortunately, we often want to build something and don’t have suitable dry wood in our warehouse. In such cases, we use drying processes that are not so gentle but are quick. This method includes microwave drying. However, we cannot recommend this method from an ecological perspective as it requires a lot of energy. That is why we rarely use this option.
How Microwave Drying Works
Microwave drying is the fastest drying method we know. But, unfortunately, with this method, it happens that drying cracks appear. But often doesn’t matter because it doesn’t affect the product’s appearance if it is cracked. That is why this procedure has its justification.
Step by Step, Dry the Wood in The Microwave
The wood is always heated in short cycles in the microwave. Then you take it out and let it cool down.
We chose heating for 90 seconds at 600 watts for a cycle and achieved good results with it.
Between the cycles, you have to weigh the wood again and again and note the weight.
The process is repeated until the weight of the wood no longer changes. Then you can be sure that there is no more sap in the piece of wood.
We needed about five passes for a trumpet tree square, spread over a total of one hour of drying time.
The Following Means Are Suitable for Sealing the Wood:
- Fine balance
- Slip of paper
“Microwave drying is a rapid method. Drying cracks only occur occasionally, but from an ecological point of view, this method is only recommended in an absolute emergency.”
Gently Dry Wood by Boiling It in Salt Water
Another drying process with a long history is the boiling of wood in saltwater. The Nordic peoples still use this method when they make their kuksa cups out of wood.
This process not only dries the wood without cracks but also disinfects the wood and kills all fungi. This is why decoction is particularly suitable for wood that will later come into contact with food.
One disadvantage, which does not necessarily have to be a disadvantage, is that the wood will discolor. This is because it practically ages from the water. That’s why it usually gets a little darker when it is cooked. However, since the wood will discolor over the years anyway, we can live with it.
Boil the Wood Step by Step
Put your wood in a saucepan with water. Add enough water to cover most of the wood but prevent it from boiling over.
Unlike in the photo below on the right, we usually put several scantlings in a large saucepan and close the saucepan with a lid during the cooking process.
Then we add about 300 grams of salt to the water. There can be too much with this one. The method does not give. Therefore we add salt to the water rather generously.
We then cook the wood at a low temperature for about 90 minutes. The water changes color like tea.
A little tip: if you reduce this liquid, you can use it as a dye.
After about 90 minutes, you can drain the water and let the wood finish drying in the apartment or workshop.
The boiling sponged all of the sap out of the tree cells. So now there is only saltwater in the cells. And this dries completely after a few days. So you have workable wood after a short time.
The Following Materials Are Required
- Table salt
- Cooking Pot
- Heat source
“The cooking process is a great way to get wood that can be worked quickly. The result is correct, and the procedure is definitely to be recommended.”
Dry the Tree Slices without Cracks by Watering Them in The Stream or Lake
The fourth drying process that we present to you also has a long history. Soaking freshly felled wood.
We like to use this method for tree grates and larger wooden blocks. First, the pieces of wood are placed in a body of water for a few weeks. This flushes the sap out of the wood again.
You are probably wondering how this procedure was used earlier?
You know for sure that our ancestors used to take the freshly cut wood to the sawmill by the river. And that is exactly where this process took place.
Even today, many sawmills let the saw logs float in a lake. But by and large, the process became less and less important with the invention of the drying kiln. Only if the logs cannot be processed immediately do they go to the so-called wet storage facility.
Tree Grates and Smaller Trunks Can Be Easily Dried in The Stream without Cracks
What used to work on a large scale can now be done just as well on a small scale, provided you have a large or flowing body of water on your doorstep. Although the method also works in a rain barrel, you have to change the water here every day to not tip over, and the piece of wood becomes unusable.
If you want to water tree grates, you need a basket around which water can flow. We used a grill basket with rabbit mesh for this. But an old washing drum is also well suited for this.
And now you also know why driftwood can be processed immediately. It is wood that has already been watered and therefore is usually free of sap.
Now all you have to do is put your wood in the container, put it in the water, and tie it to a tree to prevent it from swimming away.
You then leave this device in the water for two to three weeks. The wood can then be dried in the workshop, like driftwood.
“Watering wood is an ecological method and is recommended if you have a suitable body of water.”
Drying Tree Slices Is a Game of Chance
Tree grates crack very easily. Even if you use the methods presented correctly, there is always a high risk of breaking anyway. This has to do with the fact that there are simply higher forces at work in the core than on the outside when drying.
So don’t be sad if the tree slice cracks. It’s the rule rather than the exception. Nevertheless, the methods presented can certainly help to prevent the tree slice from tearing. Because if you just leave it out to dry, you can assume it will tear 99 percent of the time.
Dry Wood in Shavings or Hay without Cracks
In particular, farmers and carpenters used to have another drying tree grates and the like as gently as possible. In this process, the freshly cut wood is either placed in a pile of chips or hay.
In this process, the moisture in the wood is evenly transferred to the chips or hay. This enables gentle and, at the same time, faster drying.
And of course, as hobbyists and do-it-yourselfers, we can also use this drying process for our purposes. All we need is a mortar tub filled with hay or shavings. Alternatively, a large plastic bag is also possible. We can then put our wooden blanks in there to dry.
But be careful: With this drying method, you must check the blanks again and again for mold or mold stains, as these can often appear on the wood.
In this case, only a – at least short-term – switch to the air drying method will help.
Turners like to use this procedure when they have turned their bowls wet. You use the chips accumulated to dry the shell blanks and get even drying without cracks or warping.
Drying Wood Gently and Quickly Is (not) a Science
As you can see, drying wood crack-free is not that easy. The methods presented are also not a 100% guarantee that your sawn timber will remain crack-free. On the one hand, it depends on the type of wood itself, and many other uncontrollable factors also play a role in whether your wood remains crack-free. On the other hand, it will simply be a natural product, and completely controlling nature has never worked.
But what we can say, these methods increase the likelihood that your wood will dry out crack-free. And so we hope that we could teach you something new again. And you’ve found a good drying method for yourself.