Bending wood can help you reduce the waste of resources and time. There are many projects that use wood with a bend in it. The first instinct of many people would be to cut that bent-up shape of the wood out of a single stock. However, if you bend wood, you can just use one straight piece of wood and avoid waste. How does one bend a very hard material like wood though? You bend it after you soften it! In this guide, we will guide you all there is to know on how to soften wood for bending!
When it comes to softening wood, the best way is to soak it and then steam it. Wood is made out of millions of fibres, which constitute its structure. There are a few other components at work here as well. Lignins play a major role in the hardening of wood. So after you introduce it to moisture and then heat the moisture content, the fibres soften. This allows you to bend wood which otherwise would be impossible since the lignins harden the fibres.
It is impossible to bend wood without softening it first unless you use the cold laminate method. In this method, you are using wood strips which are already very flexible. By using that flexibility, you bend wood before the glue dries and sets. Once the glue sets, the strips stay bent, but this method does not rely on making wood soft. It relies on the flexibility of thin wood strips.
Ultimate Guide to Softening Wood
To soften wood you just need to increase the moisture content of wood by soaking it for a period of time. Depending on how the wood was previously dried, you need to soak it for 1-3 days. When wood is air-dried, it allows the natural air and weather conditions to evaporate the moisture in it. However, when the wood is kiln-dried, it uses the heat of the kiln to evaporate the moisture faster.
In air-dried wood, you still have about 10-15% moisture left in the wood. Since there is more moisture in it, its ability to absorb moisture is better than kiln-dried wood. In kiln-dried wood, there is only 5-6% moisture left in the wood. Because of that, it takes time for the wood to absorb water properly as fast. This is why you don’t need to pre-soak wood for too long when it is air-dried before you steam it for bending.
You can also add fabric softener to the water in which you are pre-soaking your wood to further soften it. The fibres that constitute wood are similar to that of the clothes, so using fabric softeners aids in the process.
Science Behind Softening Wood
So as we briefly spoke about it previously, wood is made of fibres. These are not very different from how fibres in clothes are. Though you also have lignins along the wooden fibres which is the reason why wood can be so hard. The lesser the lignins are the softer the wood will be naturally. This is why some wood is harder on the Janka hardness scale and others are softer.
When wood absorbs water, it does not soften immediately, it still needs to soften the lignins. When you heat wood using steam or boiling water, the lignins start to soften up. This is why wood loses its hardness temporarily and becomes easy to bend without breaking apart. Though as soon as the lignins inside the wood cool down, they harden again, retaining the shape they were in when they were still soft.
Why Should You Soften Wood Before Bending It?
Wood while being made out of fibres is still pretty rigid and hard. If you try to bend wood after it has been dried off, it will break apart and split. The lignin causes the fibres to harden and when you try to bend it, instead of bending, they just tear. This causes the wood to snap and break when you try to bend it.
To avoid that you need to soften the fibres first so that when you try to bend wood it does not tear or split. When you soften the lignin in the wood, it also causes the fibres to soften as well. When you soften wood by putting it in a steam box, it causes the lignin to lose its rigidity. But as we said before, it is only temporary, and it will harden again in a short amount of time as the wood cools down.
As the lignin loses its rigidity due to the high temperatures, the fibres become soft and stop tearing when you bend. This is why it is vital that you soften wood before bending it, as it will avoid tears, avoid the fibres breaking apart, prevent wood from snapping, and bend wood without any problems.
Can You Soak Wood in Cold Water to Bend It?
Since lignin requires high temperatures to soften, it is impossible for it to soften if you soak the wood in cold water. Though you need to pre-soak wood before you steam bend it. This can be done by soaking wood in cold water which allows it to absorb moisture. So to answer your question, no, you cannot bend wood by soaking it in cold water alone. You still need to provide it with a source of heat that can be done either by using hot water to soak the wood in or using a steam box.
Tips and Tricks for Bending Wood
- Pre-soaking: When you are planning on bending wood using a method that involves heat, like boiling wood in water or using a steam box, it is often a good idea to pre-soak the wood to allow it to absorb moisture. When wood absorbs moisture, the water that has penetrated will heat it up from the inside when you put it in a steam box or boil it in water.
- Use fabric softener: When you are bending wood using a steam box, try soaking wood in a fabric softener a day ahead. Since wood is constituted of fibres, the fabric softener makes them further soft. This allows for the wood to bend more easily.
- Using wood suitable for the bending method: If you are using the steam bending method, then choose a wood that best suits the method. People often use air-dried oak since it responds best to this bending method.
- Using air-dried wood: Air-dried wood is better than kiln-dried wood for bending. This is because it has a higher moisture content present in it comparatively.
- Keeping in mind the thickness of wood: When you are using any bending method, remember that the thickness of the wood will be a huge factor that will contribute to its success or failure. If you are using steam bending, then you need to steam the wood for 30 minutes per inch of thickness.
FAQ – Frequently Asked Questions
What method is best for bending thin wood?
The cold lamination bending method works best for thin wood since it does not take as much time as steam bending does. It is structurally more secure than kerf bending as well, which weakens wood when you make kerf cuts in it.
What method is best for bending wood that is thick?
Steam bending is the best method for bending wood that is thick. You can also use kerf bending but it is slightly less effective, also it weakens the wood structurally since you are placing a multitude of kerf cuts across its surface.
How long to soak the wood in water before steam bending it?
Depending on how you source your wood, you need to soak it in water for 1-3 days. If your wood is air-dried it is not necessary to soak the wood, but it is not a bad idea to soak it in water for a day or overnight. If your wood is kiln-dried then soak it in water for 3 days and add fabric softener to aid in the softening process.
Can you bend wood without using a steam box?
You can bend wood using boiling water as well, as it pretty much does the same thing a steam box does and softens it by introducing it to high temperatures.
Is it important to heat the wood to bend it?
If you are planning on bending wood without heating it then your best bet is cold lamination bending. Of course, you can also try kerf bending as well, both of these bending methods are viable options if you don’t want to go through the hassle of making a steam box.
Final Thoughts
Wood bending is a great way to avoid waste but to achieve that you need to soften the wood first. We hope that our guide to softening wood helped you considerably if you had confusion about how to achieve it. Just remember, preparation is the key when it comes to softening wood. Not to mention the type of wood you use will also affect how the wood softens since every wood is constituted differently.
