Warped wood is a common challenge faced by those who craft with wood materials.
Although there are numerous causes of warped wood, there are also many ways to improve or fix warping that can salvage your woodworking project!
Whether you’re a seasoned woodworking professional, a crafty DIY enthusiast, or a novice woodworker hoping to nail their home renovations, this article will teach you all you need to know about fixing warped wood. We’ll explore:
- Factors that can cause wood to warp
- Different types of warping
- How to fix warped wood
- Maintaining and stabilizing the wood after repair.
Let’s begin the process of unwarping your wood planks!
Reasons Why Wood Warps
To begin, wood can become warped for a variety of reasons and can affect any woodworker. One key feature of wood warping is the inability to craft with the wood due to its misshapen form.
Unfortunately, many people do not know that warping can occur within their own homes, such as in their flooring or their furniture.
There are several reasons why wood warps, but a major theme of warpage is humidity. Wood is extremely sensitive to temperature instability and moisture levels.
Wood appears solid to the naked eye, but is actually very porous. After all, wood originated from a plant with hydration requirements!
However, there are nuances within the different causes of warping – all of which will be described in more detail as you read along.
Heat and UV Exposure
Wood warps with heat and UV (ultraviolet) exposure as a result of changes in moisture content. Wood is hygroscopic in nature, which describes its intrinsic ability to absorb moisture from its environment.
Changes in the moisture content of wood cause it to expand and contract unevenly, resulting in warping. However, the degree of heat-inspired warping depends on the temperature and distribution of heat.
Additionally, UV light weakens wood – which further exacerbates any damage caused by moisture.
Insects and Pests
There are many insects that love wood, such as termites, carpenter ants, and fungus gnats.
Although insects do not directly cause wood warping, they do contribute to structural damage and moisture imbalance of wood.
In terms of treatment options, there are several at your disposal. Chemical treatments are often used, but it is important to verify that the chemical will not disrupt the structure of your wood.
Heat treatment also can kill pests, but make sure to remove your wood from the area that is being treated to prevent further warping.
Lastly, you may want to introduce natural predators into the area where you store your wood. However, this can be costly and can disrupt the local ecosystem.
Storing Wood on Top of Warped Boards
Interestingly, storing wood atop warped boards increases moisture exposure to the non-warped pieces. Also, warped boards tend to be uneven, so storing wood on top of top of them can create an uneven pressure gradient and potentially disfigure the wood.
In summary, poor storage conditions are a large contributor to wood warping and can dampen an entire project.
Low-Quality Wood
Low-quality wood is more likely to warp as it contains more unevenness in its structure. DIY projects can get expensive, so the desire to purchase cheaper wood is understandable!
If you notice any cracks in the wood, or if there is decay, do not purchase the wood. To thoroughly assess the quality of your wood, check out this guide here for tips.
5 Types of Warping
There are five categories of warping that describe the ways in which wood grain can be distorted.
Knowing the 5 types of warping can assist you in planning and preventing damage, or in identifying any issues with your wood.
Bow Warping
Bow warping or crowning is defined by a curvature along the length of a wooden board.
In most cases, this type of warping results in a convex shape, which refers to the center of the board curving upward.
Twist Warping
Twist warping is characterized by the rotation of a wooden board.
Like most forms of warping, a wooden board can assume this warp when humidity is reduced and the board can harden into a non-linear shape.
Kink Warping
Kink warping produces an angular shape in a wood board that was previously straight and flat.
Most warping occurs due to moisture irregularities and internal stresses (such as irregular growth patterns or uneven drying).
Kink warping can affect an array of wood types, including hardwoods (for example, oak).
Cup Warping
Cup warping makes a wood board appear to cave in from the sides, forming a cup-like shape.
This shape often occurs when there is uneven moisture distribution across the wood plank, leading to differences in shrinkage and swelling across the material.
Cup warping is most frequently found in heartwood, which is the densest component of the trunk of a tree.
Crooked Warping
Crooked warping is similar to bow warping, but the apex of the wood is on the side of the plank as opposed to the surface.
To assist your visual inspection, crooked warping often resembles an ‘S’ shape. To address crooked warping, steaming techniques are often used to straighten the wood.
What You Need to Fix Warped Wood
You may have identified one or more of the primary causes of wood warping as the source of your issue, but there’s no need to worry!
Let’s explore several of the proper techniques established for managing or fixing an entire piece of warped wood.
Moisture and Steam
Moisture and steam will relax and potentially reshape warped wood, but the moisture application must be even across the board.
This technique can be done using a steam generator or any suitably sized heat source.
Your wood should undergo steam treatment for about an hour per inch of wood thickness. Once the steaming is done, let the wood rest for an extended period without applying any weight to it or moving it to another location.
The Iron Method
The iron method is typically implemented for smaller warping issues (such as cupping).
As such, it is quite an accessible and easy method to use! Additionally, this method is quite cost-effective, so long as you already own an iron.
All you need is a household iron (preferably with a steam function), a flat and rigid surface (such as an ironing board), and a moist paper towel.
Apply the wet towel to the wood for protection against scorching, and then begin to iron. After ironing, allow the wood to settle into its new shape, and do not apply any weight to it until it is cooler and fully set.
The Sunlight Method
If you’re looking for a more passive technique for correcting warped wood, the sunlight method might correct your warping issues! The direct sunlight method is used for drying wood that has been warped from excess water.
However, it might be beneficial to check that the weather conditions are appropriate for leaving your wood outside all day! Sunlight that is too strong (or rainfall) can ruin your attempt to correct the warping.
The Heat Method
The principle of the heat method is similar to that of iron and sunlight methods, but the medium happens to be a heat gun (or another heat source).
Heat guns are handheld woodworking devices that produce very hot steam that can be beneficial in a variety of contexts, including fixing warped wood.
For safety reasons, always wear protection when performing the heat method, and also ensure that your tool isn’t scorching your wood by closely monitoring the warping progress!
Jack Plane
Moving on from heat- and moisture-based methods, jack planes are utilized in removing minor sections of the wood in a gradual manner in an attempt to straighten it.
Remember: it is important to practice properly before using any unfamiliar woodworking equipment!
If you do not have excess wood to practice on, referencing YouTube videos on the subject that qualified professionals have made is an acceptable substitute.
The Pressure Method
The pressure method utilizes external pressure sources for an extended period of time to reconfigure the wood.
The pressure method can be carried out using clamps that position the warped wood in a normal shape.
The Nylon Paper Method
To return back to moisture-based approaches, the nylon paper method involves using moisture to make corrections to warping. The nylon paper method is effective for bow and crooked warping.
Lay a sheet of plastic over the flat surface of the wood and add water to it, along with external pressure – all of which should correct the concavity!
Cut And Glue Your Warped Wood To Flatten
If all else fails, cutting and reshaping the wood manually might be the best way to finally correct stubborn warping.
To begin this process, assess the warping and mark the area(s) (with a pencil) that needs to be cut.
Once the wood has been cut, use a wood adhesive to bring the usable sections together.
These sections will need to dry before they are ready to use again, so it is recommended to apply pressure to the glued area and wait for the recommended drying time (depending on the adhesive used).
Also, you may need to sand the wood after this stage to eliminate any residual warping.
It is recommended to use the correct grit sandpaper (starting with the lowest number and working your way up). For reference: the lower the number, the coarser the grit of the sandpaper is.
What To Do After Fixing Warped Wood: Stabilizing the Wood
Key Methods for Enhancing Wood Stabilization
There are a few techniques that can be used to stabilize wood after the entire piece has been remedied:
- Apply a sealant, such as a wood stain, polyurethane, or varnish. Wood that has been sealed is less likely to experience moisture invasion (and warping) again
- Reassess the environment that the wood lives in while it is not being used. Make sure that it is stored in an area without great temperature fluctuations
- Pressure can be applied to wood on a regular basis to ensure that it remains in the desired (flat) shape
- If the wood is being used in a project, applying fasteners like screws or nails is a terrific way to stabilize the wood and prevent warping.
Tips for Enhancing Wood Stabilization
Here are some handy tips for stabilizing wood that was previously warped:
- Purchase a thermometer that can stay with the wood to monitor temperature changes
- Segregate the warped from the unwarped wood to prevent contact-based warping
- To note, the wood type that is least likely to warp is cypress. However, it can still experience warpage
- Proper storage conditions are essential!
Conclusion
You’ve made it to the end of this guide to warped wood! Hopefully, you feel more informed about the causes of warping and the numerous ways to fix warped wood.
Warping can happen to anyone and is preventable by keeping your wood in a dry, temperature-controlled environment that is (ideally) free of pests.
Feel free to consult this article again as you encounter warpage in your future DIY or professional endeavors. Happy woodworking!
