Warped wood? That is one of the biggest challenges you’ll face as a woodworker, and this is putting it mildly. Warped wood completely changes the shape of your project, makes construction difficult, and makes it look ridiculous.
Of course, you can straighten warped wood, but even that can be time-consuming, stressful, expensive, or all of the above. Water and wood are sworn enemies as the water distorts the wood structure and causes warping.
Warping can occur at any stage, including after finishing the project, especially when it is placed outdoors. However, one of the most challenging phases is when warping occurs when the wood is stored before it is put to use.
Wood warping during storage happens more often than it is given credit for, and it causes a great deal of stress to fix. Prevention, they say, is better than cure. So, instead of waiting to fix the warped wood, stopping it from getting warped is a more rewarding task.
We’ll look at how to store lumber to prevent warping, but first, let’s know what is wood warping?
What is Wood Warping?
When the structure of the wood is compromised, it bends. The bending is called warping. Warping is caused when there is a more than normal amount of water inside the wood. This increases water levels and causes the wood to dry unevenly, which raises some parts and shrinks the others. The shrinking now forces the wood to bend when dried.
Warping can occur at a point in the life of the wood. Wood exposed to moisture and areas with high humidity is at risk of warping. Generally, the moisture content in the wood will try to match that of its surrounding. It dries out in a dry environment and absorbs water in humid environments. This gain and loss of water will cause wood to warp if it doesn’t happen evenly and slowly.
Types of Wood
There are different types of wood warping, and they form different shapes when they dry. You can tell the type of wood warp by the shape of the warp, the position, and the potential cause of the warp.
- Kink: kink warps bend the wood upwards, creating a sharp edge and straight lines on either side of the bend. It is caused by a knot. This bend occurs edgewise.
- Crook: the bend here occurs edgewise also, but only one part of the wood is affected, causing the wood to bend and form a C shape.
- Bow: here, the face remains flat, but the edges bend, forming a curve that looks like a bow when viewed from the side, hence its name. The face bends upwards in this warp.
- Twist/wind: this type of warping affects all four corners of the wood as they no longer remain on the same plane.
- Cup: here, the curve happens on the face of the wood with the edges retaining their flatness. The face of the wood sees the edges folding inwards and not on the same plane as the center of the wood.
How to Store Wood to Prevent Warping?
As earlier established, warping can occur at any stage but one of the most common places warpings occur is during the storage circle of the wood. Learning how to prevent warping at this stage will significantly reduce the chances of wood warping at any stage.
1. Store the Wood Horizontally
The best way to store lumber is horizontally on its sides as against vertically on its edges. This will ensure the wood lattices are at rest and not under undue pressure. Horizontal stacking of wood with the edges aligned vertically spreads the weight evenly and ensures one part does not see too much weight as another.
Ensure that the wood stack is placed on a flat foundation. The stack of wood should comprise woods of the same thickness and length. Only stack wood of the same size to ensure even weight distribution.
2. Ensure Proper Ventilation
Stacking woods of equal sizes together is one thing but without proper ventilation, some of the wood can warp. Proper ventilation into the space and between stacks is important to keep the wood in good condition.
Give some space between the stacks so ventilation can occur. Also, ensure there are enough windows or open areas so air can reach the stacks.
3. Cover in Humid Areas
Areas where the amount of water in the air is high will see the wood absorbing too much moisture from the surroundings. If you’re storing the wood in such an environment, ensure to cover the wood with materials that prevent vapor from passing through. Materials like tarp are great for preventing moisture from entering the wood.
4. Put Heavy Weight on the Pile
I know this may sound counterintuitive, but putting heavy weight on the pile of wood can prevent some times of warping from occurring. However, you need to be careful as the weight should be spread across the surface of the wood to ensure one part is not seeing too much weight than the other.
When a heavy weight is put on the pile of wood, it prevents the wood from bending. Cup warping is the major warp type that is prevented when you do this.
5. Proper Curing Before Storage
Drying the wood before storing it is a great way to prevent warping, or at least most types of warping. Curing the wood before storing it should be done with several precautions in mind.
Drying too fast or too slow will cause warping. And as well as over-drying the wood which can lead to warping at the edges and break-offs.
Drying needs to be done at the right speed and evenly, which is why kiln-drying is quite popular. Kiln-drying gives you control over the drying process so you can regulate the drying speed to ensure proper curing before storage.
Using a kiln to dry the wood also protects the wood from insect attacks.
6. Store in a Clean and Dry Place
Storing the wood in an environment that is clean and dry cannot be stressed enough. Select an area that is free from dirt, fallen leaves, and broken branches as they not only look unsightly but can also be rotten and bring moisture.
The temperature of the area should be cool, not too hot, and not too cold. Optimum temperature enhanced by a shade that prevents direct sunlight from hitting the wood will ensure the wood does not completely dry out.
A shaded area will also prevent rapid drying of the wood which can cause warping. The site of storage can affect the condition of the wood you store there and that is why you need to take getting an ideal location seriously.
7. Monitor Moisture Levels During Storage
If you’re dealing with a lot of wood and storing it for a long time, you’ll need to go beyond drying before storage. You’ll need to seek methods to keep water levels minimal throughout the storage period.
Monitoring the moisture levels during storage includes measuring the relative humidity in the air and the moisture content in the wood. Keeping these two in check will ensure your wood remains in pristine conditions away from any form of wood warping.
Hygrometers installed in the storage area can measure the relative humidity of the space and give you accurate results. Calibrated prong-type moisture meters measure the moisture content in the wood.
The prong-type meters allow you to measure the surface moisture and inner moisture of the wood as this can vary. Use these two instruments to keep the moisture in the wood at an optimum level throughout its storage period.
These instruments do not come cheap and that is why this method is suited to large factories that deal with a lot of wood stored over a long time rather than small woodworkers.
8. Seal the Wood Ends
The end of the wood is usually the first to warp and this is because it is the most exposed part when the wood is stacked. To prevent quick warping of the wood, seal the end of the woods with waterproof materials, so moisture is not lost or gained. This method is best used when storing wood for a short time. When wood is stored for long, both the ends and surface of the wood can warp, so this method will no longer be quite effective.
Here are extra tips to guide you when storing the lumber:
- Minimize the level of expansion and contraction: This process leads to warping, so minimizing it as much as you can reduces the chance of warping.
- Treated wood warps easily: Wood that is treated is soaked in liquid to coat it with the necessary materials. This soaking process requires drying, which oftentimes occurs unevenly, causing warping.
- Kiln-dried lumber should be stored inside: this is because it has been cured and is seasoned, so it needs protection.
Woods can be stored for a long time for a project or even for sale. Keeping the wood aware of warping is an important activity that starts from when the wood is brought in till you use it.
Luckily, there are several ways to store wood that’ll prevent it from warping. These methods can be used separately or combined for the best results.