How To Bend Wood With Water: What You Need To Know
Wood is humanity’s oldest and perhaps favorite building material. It has remained as popular in the 21st Century as it ever was ages ago. Bending wood is a tricky proposition in the sense that first, wood easily breaks and second, the concern of retaining the bent shape. Several methods and techniques of bending wood have been discovered but the most economical and by far the most popular is using water- hot water, or steam for that matter. This article aims to explore the wood bending method that entails using water, the proper techniques, requirements, and the science behind it all.
Conditions Necessary For Bending Wood
In order to bend wood properly, several factors need consideration. They are as follows below;
1. When attempting to bend wood, only air-dried wood of the right species is suitable for use. Wood dried in a kiln should not be used as the lignin in the wood fibers permanently sets during the drying process. Regardless of steaming and soaking, the lignin bonds will not weaken sufficiently for any successful bending. The same principle applies to air-dried wood that has been dried and stabilized to below a 10% moisture content. The lignin in the wood will partially plasticize with steaming but it won’t be enough for successful bending of the wood beyond a slight curve.
2. As mentioned above, wood cells are tightly held together by a naturally occurring material in the wood called lignin. To perform any successful bending, it is necessary that the wood is first plasticized. This means the application of steam to levels whereby the lignin bonds in the wood weaken allowing the fibers to bend. This is achieved using unpressurized steam at 100°Celsius. The recommended time for steaming is one hour per inch of wood regardless of the width. Substantial application of steam for periods longer than is recommended may cause the wood to wrinkle on the concave side of the bend as the bending process progresses.
3. While bending wood, it is important to keep it under compression. This means clamping the wood. This prevents the wood fibers from stretching which often causes the wood to break. To stop the wood fibers from stretching during the bending process, it is recommended to restrain the wood on either end by using stops securely attached to metal backing straps. Wood fibers are known to stretch by a small margin before they break which is usually less than 1%. The drier the wood, the likelier the possibility of the wood breaking during bending.
4. Exotic wood is not the best pick for bending as it tends to break easily; a fact attributed to the wood’s cellular structure. Softwoods are also not recommended for use and should be avoided at all costs. Common household hardwoods ae the best bending candidates with impressive success rates where the wood moisture content is above 25%.The ability of solid wood to bend gives woodworking and carpentry projects both an aesthetic appeal and a structural/mechanical advantage. This method is called ‘bending wood using water” primarily because water in gaseous form is used to weaken the lignin bonds in wood effectively plasticizing the wood.
Bending Wood: The Requirements And Procedure
1. A means of generating steam: Depending on the size of the planks of wood being used, the size of the steam generating contraption varies between volumes slightly higher than a standard kettle to commercially sized steam generators.
2. A set of clamps which are useful in holding together the wood during bending.
3. A bending table of a sort of bending template. A bending table allows for the bending of wood into various shapes such as U-bends, 90° bends, S-shaped bends and simple curve bends among others.
4. Tools you may need:
- Place the wood planks in a suitable holding and steam generating container. It is recommended to have a pressure release mechanism to avoid a risky buildup. Pressurized steam has also been noted to have a drying effect on wood. Leave the wood to soak in the hot steam for about an hour.
- Carefully remove the hot planks and align them in order. Tightly clamp them together while making sure that the planks are well positioned and secured to avoid any surprises. Place the wood on the bending table as soon as you’re done with the clamping bit. Depending on the desired shape, slowly bend the wood while using extra clamps to hold the wood in shape. Try not rush the bending process as mistakes are bound to occur. To single pieces of wood, the process is similar and perhaps simpler.
- Check for any errors in the wood’s alignment and correct appropriately. Take note that as the wood cools, the shape it is in will settle and hold, so it is important to pay keen attention to the actual bending. You might want to use a holding bracket in cases where more than one plank of wood is being bent. This allows the planks to get bent in the same direction.
- After the bending is complete, allow the wood to sit for about an hour or two. The wood loses heat and the lignin acquires a new form/shape. Once the wood is cold, the shape should hold.
1. Be extra careful when working with boiling water and steam. The risk of injury by scalding is high. In under no circumstances should the steam generator be allowed to accumulate pressure. Remember that pressurized steam has a temperature higher than the boiling point of water.
2. Use heavy duty gloves when handling the steamed wood. Your hands may suffer injury if you attempt any bare-handed manipulation of the wood.
Wood is beloved for its beautiful texture, grains, and appearance. The ease of manipulating wood into different shapes and structures is an added advantage. Although bending wood is an elaborate affair, the results are permanent. Using water to bend wood is among the easiest and cost effective methods available. Others include the use of Ammonia and microwaves to bend wood.
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