How To Straighten Warped Wood – 4 Effective Methods
Wood that is properly cared for can last a long time, but often it can succumb to warping and splitting over time.
In fact, if your profession involves working with lumber, then you probably know exactly what “deformed” wood looks like.
But where there is a problem there is a solution, and it is indeed possible to unwarp your bent wood.
Before we learn how to straighten warped wood, we should first understand how wood warps in the first place.
What causes wood warping?
Warping is a deformity in wood that usually results in bowed and unusable boards. This happens when different parts of the wooden board experience variations in moisture content.
For instance, when one part of a piece of wood dries quicker than the other, the part which dried faster will end up shrinking faster as well. This results in stress, and gradually, the shape of the board can change. Thus, a piece of wood that was flat ends up warping.
Here are the different types of warping that can occur in wood:
There are other factors that can contribute to wood warping, including:
- air flow
- temperature and sunlight
- grain orientation
- wood species
- whether or not the wood has an uneven finishing
What are some ways to straighten warped wood?
Though there are some ways to prevent wood from warping, including stacking the wood the right way, sealing the ends, painting or staining the wood, and other things, if the wood has already warped, all is not yet lost.
For a visual and additional insights related to using winding sticks, check out this video:
There are a few ways you can straighten it, and here are four of the most effective methods for doing so:
1. Use winding sticks.
The first method to fix your bent wood is to use winding sticks. Follow the steps given below:
You need to understand the kind of warp you’re facing. A pair of winding sticks very easily helps you identify bows or twists.
Keep the wood on a flat surface, and place the winding sticks on either end of your piece of wood. Sight across the top edges of the sticks and look for any unevenness; if they are not parallel, then it means there is some deformation on the surface. To rectify this problem, diagonally plane the wood along its high line.
Here’s a visual of how winding sticks are set on top of wood:
To find out if your wood is bowed, you can even use one winding stick.
Move the stick along the wood’s surface. If there is any space between the wood and the stick, then the wood is warped.
You can even check for space in between the two edges while sliding your stick. If you find the wood looks low in the middle part, which means there is cupping across its width, then you can make cuts that will help in removing the high sections on the edges. Make sure you do this across the length of the wood.
If you notice that the wood looks raised in the middle, you can make cuts only in this region to create a piece that is flatter in the center part. Now, repeat the above-given steps to finish the flattening.
2. Use sunlight.
It is a known fact that water and direct sunlight can deform wood. The goal here is to warp the wood back in the opposite direction in order to flatten it.
In this case, you should wrap the warped wood with moist towels. Select a cloth that will easily retain moisture.
Soak your chosen towels in water, remove the excess, and follow these steps:
Keep the wood on a deck or any other similar flat surface. The wood must be placed in direct sunlight with the section that is bent inwards facing down and the section bent outwards facing up.
Spray more water on the wrapped wood if needed. Keep in mind that, depending on the degree of the warping you have, you’ll need let the wood stay out in the sun for 2-4 days.
Make sure that during this period you continue to spray water on the wet towel to keep it damp. Sunlight will help the wood absorb moisture from your towel in an efficient way. At night time, keep the wood in a warm place.
Depending on the damage that the wood has sustained, it can take some time to see the desired results. You should keep checking on a regular basis to see out if your wood has unwarped.
Once you achieve your desired result, remove the moist towels and allow the wood to dry. However, if you do not see any substantial results, you can try the other methods given here.
3. Use an iron.
With this method, you also need an iron and moist towels. Make sure the towels you select can bear an iron’s high temperature.
Follow the steps given below:
Wet the towels in a bucket of water, take them out and get rid of the excess water. You need to make sure the towels are damp — not sopping.
Wrap your warped wood in two large moist towels and make sure the warped parts are properly covered.
Now, keep your wrapped wood on a flat surface that also will be able to bear the temperature of your iron. The concave part needs to face downwards.
Set your iron to the highest temperature and let it heat properly for about 2-6 minutes. A steamed iron will work best for this purpose.
To flatten the bent wood, you have to press your iron on the warped area. Keep sliding the iron over the whole surface of the wood, and while doing so, apply consistent pressure. In each area you cover, hold your iron for a minimum of 5-10 seconds.
See how it can be done in this video:
Never leave your iron on the wood and walk away; this can damage the wood, and more than that, it may cause serious injuries when you try to touch the towel.
Observe if you have managed to correct the warping. If yes, then stop this process and let the wood dry before you use it.
4. Use pressure.
The key thing here is tightening with a clamp or similar device. You need paper towels for this method. Follow these steps:
Cover the warped hardwood (specifically the concave portion of the wood) with moist paper towels. Just like in the other methods, you should rinse the paper towels under water and wring out the excess.
Again, to bring the wood back to its normal shape, you must concentrate on the concave section.
Wrap the wood and paper towels with several layers of plastic. Do it tightly and securely. This will help to reduce evaporation of the moisture in the paper towels, allowing the wood to absorb more of it.
Place the wood in a clamp, making sure to tighten it with a great amount of pressure until the warped parts start straightening. You have to be very careful here or else you might end up splitting the wood.
Allow the wood to sit for at least a week, but during this time, checking for any damage. Store the wood in the warmest environment you can achieve, ideally at a temperature of about 65 degrees Celsius.
After one week, remove all the coverings – the plastic and the paper towels – and see if the warping has been reversed. If it has, then you can let the wood dry and then use it.
However, if the problem has not been resolved, then apply more pressure with clamps and let the wood dry for two to three more weeks. At this point, the wood should ideally be stored at about 25 degrees Celsius.
Keep checking the progress and unclamp your wood if the warping is corrected. If you are not seeing satisfactory progress with this method, your wood may be beyond saving.
Warping can indeed prove to be expensive to deal with in the wood industry. However, thanks to the methods given above, instead of dumping the warped wood, there is a good possibility of being able to straighten it and use it again.
The best thing is that each of these procedures is easy to follow, hardly costs you anything, and typically produces very good results.
So, the next time you face the problem of warped wood, give these techniques a try. Chances are you’ll be glad you did!
If you’re interested in learning how to cut and work with wood in a professional manner, I strongly recommend checking out the other woodworking content on the site, including this article on CNC machines.
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