After you bought a wood board from local hardware stores, a few weeks back you’ll notice it got warped, and can’t use it anymore. Warping wood is one of the biggest nightmares for any woodworker. This happens due to the fluctuations of moisture amount inside the wood. When I was facing the wood warping problem for the very first time, I was curious to know, How to keep wood from warping?
I’ve researched and here’s what I’ve found:
You can keep wood from warping by keeping wood in a clean, dry storage area with proper storage techniques, monitoring the moisture content of the wood, curing the wood properly, acclimating wood before installation, and controlling the cutting of boards. Those methods will help you to keep wood from warping when cutting, painting, and drying.
But that’s a quick snapshot and there’s a lot more to know about wood warping.
So, in this article, we’re diving deep into the hot topic of how to keep wood from warping and discuss the best methods to keep wood from warping in detail. Furthermore, we’ll discuss what causes wood to warp, how to fix wood warping, and answer some frequently asked questions as well.
So, let’s get going!
May Maintenance: Outdoor wood— Rachel Frentsos (@RachelFrentsos) May 6, 2021
Cold & wet weather causes wood to move, twist, & warp. That can make wood fall out of alignment, loosen, or fall off. Check for signs of wear and repair.#rachelshomes #rachelfrentsos #annapolisfinehomes #homesweethome #realtor #lovewhereyoulive pic.twitter.com/SQfLVzPIUb
What Causes Wood To Warp?
Wood warp when the moisture content of the wood changes unevenly throughout the surface.
For example, you have a block of wet wood, and you’ll keep it dry. But when it dries some areas of the board dry faster than other areas causing drier areas to shrink faster. Because when the wood dries it tends to shrink by releasing its water content. But when some parts of the woods shrink faster, but others don’t that causes wood to warp.
Wood warp due to various factors. Such as,
- High moisture content
- Less moisture content
- Ambient temperature
- Wood type
- Wood thickness
- Woodgrain orientation
- Protective coatings
Wood is a natural material made with fibers with a porous structure. Those pores will absorb and release moisture to the outside environment.
When the environmental humidity is high, wood tends to absorb moisture from outside which causes wood to expand and swell. When the environmental humidity is low, wood releases its moisture to the outside environment which causes wood to shrink.
Likewise, balancing the moisture level of the outside environment and moisture content of the inside of wood at a steady state is known as the Equilibrium Moisture Content (EMC).
Wood warping happens mostly when EMC is unstable. When EMC is stable, wood is neither losing nor gaining moisture. At a stable EMC moment, moisture losing speed is equal to the moisture-absorbing speed or no moisture release or gain from the outside environment.
One reason to take care of moisture in the floor is that wood can rot over time. If left untreated, wood can warp and ruin your floor! pic.twitter.com/7skGV3ATwJ— Home Services Foundation Repair Inc. (@FoundationSlabs) December 28, 2018
How High Moisture Content Causes Wood to Warp?
When the moisture content of wood inside is high, it is already swelled and expanded. If the outside environment has less humidity with less moisture content, wood tries to release water to the outside environment. When it dries by releasing water into the outside environment, it shrinks back down. This incident happens to stabilize the EMC.
But not all areas of the wood shrink equally by releasing water to the outside environment at an equal rate. Some areas dry faster and shrink faster while some areas dry slowly and shrink slowly. When different areas of the wood dry at different rates, this can stress the wood and change its shape permanently. This is how high moisture content causes wood to warp permanently.
Wet mopping is not recommended for wood floors as excessive amounts of water can cause the floor to swell or warp. pic.twitter.com/Jkm7WUoIeA— Floor Sanding HS (@FloorSandingHS) July 13, 2016
How Less Moisture Content Causes Wood to Warp?
When the wood is dry, it is already shrunken. If the outside environment has high humidity with high moisture content, wood tends to absorb water from the outside environment and expand. When it gets wet by absorbing water from the outside environment, it will swell. This happens to stabilize the EMC value between the wood and atmosphere.
But not all the areas of the wood absorb water at the same rate. Therefore, some areas get swell faster by absorbing water faster while some areas swell slowly by absorbing water at a slow rate. When different areas of the wood swell at different rates, this can stress the wood and change its shape permanently which causes wood to warp.
How Ambient Temperature Causes Wood to Warp?
When the outside temperature is high, air can accommodate high, and humidity will also increase. High environmental humidity affects EMC and the wood need to absorb moisture faster to stabilize EMC with the outside environment. If the wood is dense and unable to exchange water faster along with the changes of EMC, that causes wood to warp.
The same thing happens when the outside temperature is low. Air accommodate less and humidity will decrease. So, would need to release its moisture at a high rate to stabilize EMC. Otherwise, the wood will stress out because of the EMC imbalance and tend to warp.
Even hardwood has a tendency to slightly warp, shrink or grow according to temperature and humidity. The best advice on how to take care of your wood floors is to treat them like an investment. #home #homeimprovement #interiordesign #decor #property #bespoke #homeinspo pic.twitter.com/9G2tcWqIiP— Orangeries UK (@OrangeriesUKltd) June 5, 2018
How Wood Type Causes Wood to Warp?
Density, hardness, and wood structure can cause wood to warp. If the wood is highly dense and it cannot match or go parallel with EMC changes the wood will stress out and causes wood to warp.
For example, Cedar has a natural resistance to warping because it has natural chemicals and oils inside the wood. This oil helps the wood to easily exchange water with the outside environment and balance EMC faster. Therefore, wood doesn’t stress out and no warping happens. Redwood and Douglas Fir also have similar kinds of oils that protect the wood from warping.
Wide and dense hardwoods are prone to warp. Even some of the softwoods warp because of their wood structure. Generally, close grain woods have less tendency to warp than open grain woods. Close grain woods have less spacing between their wood fibers. Therefore, they cannot shrink much as open grain woods with lots of spaces between wood fibers.
How Wood Thickness Causes Wood to Warp?
Thick pieces of wood take more time to absorb or release moisture from the outside environment. When the wood thickness is high it cannot reach EMC faster.
When the wood has a relatively high moisture content, it shrinks and dries until it reaches equilibrium with a relative outside environmental humidity. But when wood thickness acts as a barrier, this water exchange process will slow down, and the wood starts to stress by unbaling to adjust for those types of conditions.
As a result of excess stress on the wood, wood warping will happen.
So I’m going to try and make this into a bowl today. It Olivewood and Redheart. There is too much moisture in the Redheart and it makes thing difficult. You can see the cracks where the moisture was trying to escape. It warped the wood a little but will try anyway. pic.twitter.com/iwKodkuCGL— DTM Woodworks (@DTM_Woodworks) January 20, 2022
How Wood Grain Orientation Causes Wood to Warp?
Wood logs that cut perpendicular to the wood grain absorb moisture more quickly than logs that cut parallel to the wood grain.
Plus, when the wood grain is placed much closer, those woods penetrate less moisture. As a result of penetrating less moisture content from the wood, it doesn’t shrink much and is less likely to stress up which causes a permanent change in wood.
Therefore, grain direction is highly affected by wood warping.
To prevent cutting board warp, make sure the wood grain runs mostly perpendicular to the cutting surface (see photo) pic.twitter.com/2sKolOh6aq— CompassCuttingBoards (@CompassCutBoard) November 13, 2013
How Protective Coatings Causes Wood to Warp?
Protective coatings seal the wood and slow down its water absorbance and releasing rate with the outside environment. This will reduce or prevent the wood from shrinking or swelling. in other words, protective coatings cut down the direct relationship between wood and the outside environment.
If you apply protective coating only for some areas but others remain without a protective coating, those unprotected areas exchange water with the outside environment and cause wood shrinking and swelling, but protective areas don’t. As a result of that stress will be generated between wood fibers of protected and unprotected areas. If the stress build is long term, the wood will change its shape and adjust accordingly. This incident causes wood to warp.
So, always make sure to apply protective coats like stain, paint, and sealer to the whole wood surface equally with the same number of coatings to prevent wood warping.
Types Of Wood Warping
There’re main five types of wood warping. They are,
- Twist or Wind
So, let’s find out each type of wood warping in detail.
|Wood Warping Type||Description|
|Bow||Warp long the length of the wood, not across the face. The shape resembles a bow|
|Twist / Wind||Warp by turning four corners of any face of the wood board. They’ll be no longer on the same plane. The shape resembles a twisted ribbon|
|Kink||Warp the wood edge from a straight line like an elbow.|
|Crook||Warp along one side of the wood. This occurs when only one edge of the wood is exposed to moisture. One edge shrinks while the other edge remains the same which causes warp.|
|Cup||Bend through a straight line across the width of the wood. Bend inwards and results in a curved shape in the middle.|
Do you know the common terms for the types of wood warp? pic.twitter.com/SJOZOPeX5R— Everwood Treatment (@EverwoodCo) January 11, 2016
So, let’s have a look at the top 5 easiest methods to keep the wood from warping.
Top 5 Methods to Keep Wood from Warping
- Store wood in a clean and dry storage area with proper storage techniques
- Monitor moisture content
- Cure the wood properly
- Acclimating wood before installation
- Controlling the cutting of boards with sawing techniques
By following the above 5 methods, you’ll be able to protect your loving furniture, woodwork, and lumber from warping.
So, let’s discuss each of the above methods separately.
1. Store Wood Using Storage Techniques
To keep wood from warping you should keep wood in a clean and dry storage area. The way you stack wood is one of the main things for how it will change when it adjusts to EMC. Because wood warping mostly happens by exposure to moisture. By preventing the wood from getting in contact with moisture, you’ll be able to keep wood from warping.
To store wood properly, you should follow storage techniques. Such as,
- Place woodpiles onto flat foundations
- All boards and stickers that are placed need to have a uniform thickness when placed in the same layer
- Stickers should align vertically and lay flat
- Spaces between woodpiles are essential for proper ventilation
- Weights need to be placed on wood plies to avoid cupping
- Cover wood with a material that protects wood from vapor to keep the wood dry in humid areas. Use vapor impermeable material to avoid wood from absorbing moisture from the outside environment, especially in humid places.
- Store wood in a clean dry area with a high humidity level (80% or more)
Always make to focus on the humidity of the outside environment, because if the wood absorbs a high amount of water from outside, it’ll stress out and warp easily.
2. Monitor Moisture Content
To keep wood from warping, the moisture content of the wood needs to monitor frequently. Plus, you have to make sure the storage area is also free from moisture and humidity. Testing moisture content is crucial to producing high-quality wood.
The humidity of the storage area can be measured by using hygrometers and the moisture content of the wood can be measured by using prong meters from the surface to the inner area of the wood.
You should measure the moisture content of the wood surface and interior both because those measurements can vary by one to two percent. But both values have to be in a pretty low state to consider them free from moisture and water. If the moisture content of the surface and interior are too different, the wood drying process needs correcting.
For example, if the surface of the wood is dry and the interior is wet, that means the kiln is operated at too high a temperature causing surface to dry faster than the interior. This will stress out the wood and leads to wood warping.
The moisture content of the wood needs to be measured at each production stage. Because if a wood warping happens, it is easier to detect which production stage is responsible for that.
When you are taking measurements of relative humidity of the storage area, follow the below guidelines to get the best results. Such as,
- Avoid places with restricted airflows like corners and alcoves.
- Check the sensory element of the relative humidity meter before taking measurements to make sure it has not been damaged.
- Take multiple relative humidity readings and take the average value of it to get the most accurate result.
- Seal or stain the ends of the wood to prevent them from warping. Because wood ends dry faster than in other areas. By sealing endings they won’t dry faster than the rest of the wood.
The below table shows how the moisture content of wood should vary along with the relative humidity of the outside environment.
|Relative Humidity of Outside||Moisture Content of the Wood|
|99%||23% – 30%|
If the moisture content of the wood and relative humidity of the storage area is too different than the values of the above table, the wood is already stressed out and tends to warp.
3. Cure the Wood Properly
Curing the wood properly is important to protect the wood from warping. Curing will increase the wood’s durability. By curing you need to make sure the woods are completely dry before storing them in a storage area.
Follow the below instructions to cure wood properly,
- Never allow woods to dry slowly because their moisture content stays there for long enough that resulting in wood warping
- Never expose drying wood to moisture or water
- Over drying should be avoided because that will lead to cracks and splits
4. Acclimating Wood Before Installation
Your wood should always acclimate before the installation. By acclamation, you can get your wood close to the EMC value as possible with environmental humidity.
For example, if you’re working on woodwork or furniture that will be shipped to another area that has a different climate, humidity, and other weather condition should acclimate the whole woodwork by treating it with wood stain, paint, or sealer.
By applying protective coatings, you will be able to stop its moisture exchange relationship with the outside environment and stop wood warping permanently. The woodwork can be used in any area you want where it’ll be exposed to different moisture levels indoors and outdoors.
Water is the biggest enemy of wood. Waterlogged wood will warp and rot quicker. Water can also cause discoloration on the surface of the wood. Stain provides a protective layer between the wood and water, so your wood structures will last for years to come. pic.twitter.com/vWMb7MOX5l— Texas Best Fence (@TexasBestFence) October 18, 2019
5. Controlling the Cutting of Boards With Sawing Techniques
It is so much difficult to control the cutting direction of the wood and avoid wood warping in the future. There’re main 3 cutting methods boards. They are,
- Rift sawn
Rift sawn creates the most stable wood but the wastage is high. In Rift sawn wood log cut perpendicular to the growth rings of the wood.
Flatsawn creates unstable wood but the wastage is less. In Flat sawn cut the lumber flat by ignoring the wood grain.
To have high stability and less wastage you should go with the Quartersawn method which gets closer to the wood grain by making it less wasteful and highly stable with less likely to warp.
Woods that are cut from the heart of the trees are more stable and resistant to wood warping and shrinking. Straight grain woods with 1/32-inch (0.79 mm) space between grain lines are less likely to warp.
Consider flat – rift – quater sawn lumber.— Brian Roemmele (@BrianRoemmele) November 3, 2021
Quarter sawn lumber is considered more dimensionally stable and was usually found in the US from top lumber yards for generations. pic.twitter.com/kSpW4T1b6h
So, that’s all about the top 5 methods how to keep wood from warping. So, let’s have a look at some tips to keep wood from warping.
Tips To Keep Wood from Warping
- Never expose wood to excess moisture or water.
- Avoid fast drying and always go for a slow drying process because the drying speed of the wood surface and interior cannot be too different.
- Always use fresh woods to make woodwork and furniture
- Apply a good finisher to every woodwork to avoid wood warping. Never leave without applying a protective coating.
- Avoid excess drying because that will lead to wood crack and splitting.
Working with new wood is always nice but there is something to say for taking old useless warped wood and turning it into this pic.twitter.com/fjAtTDWPgm— Wonko the Sane (@Adam_Watts77) May 23, 2020
How To Fix Warped Wood?
Fixing warped wood is possible. Fixing wood warping is somewhat different than keeping wood from warping. Fixing wood warping is easy if you follow the correct procedure.
Before fixing warped wood, you need to have a clear idea of how wood warping happens. It happens due to the fluctuations in moisture content between relative humidity and wood interior. So, by adding or releasing moisture you’ll be able to clamp wood into its original shape.
You can fix warped wood with the help of moisture and heat. Heat speeds up the moisture absorption rate of the wood. Iron is equipment that uses moisture and heat which is useful to fix warped wood.
Turns out that you can flatten warped wood by (steam) ironing it pic.twitter.com/9zXRyy7ydp— Gavin Deichen (@gdeichen) January 19, 2020
Here’re some popular methods of fixing warped wood,
- Spray down the wood and let the wood absorb moisture. Once the water has been absorbed, camp the wood in a fixed position and let it dry. When the wood dries it will eventually regain its original shape.
- Take a wet towel and place it on the warped area. Then take the hot iron and place it on the wet towel and allow the wood to steam. This will generate heat and moisture at the same time. heat will increase the moisture absorption speed and relax wood fibers quickly to gain their original position. Then clamp the wood and let allow to dry.
- Warp wood in damp towels and leave it under direct sunlight for two-three days. Sun’s warmth relax the wood fibers and helps to regain the original non-warped shape of the wood.
- The steam machine can affect the whole wood area once to fix warping. It has a boiling water tank and water is fed to the wood through-hole-filled surface.
- Ironing machines function like steaming machines except they only heat the wood. Wet wood is placed on a heated ironing machine to relax wood fibers and clamp it until it reaches its original shape.
The wet towel method and steam machine method are the most popular method to fix warped wood because they use heat and moisture both to un-warp wood.
When you are working with ironing machines and steam machines to fix warped wood, you should be careful not to burn or damage wood because of excess heat.
What Woods Does Not Warp?
Most of the woods warp when they are exposed to moisture. But some woods are warp-resistant because of chemicals and oils inside the wood.
Woods warps the least are,
- Douglas Fir
- Yellow Poplar
Above woods are excellent for outdoor woodworking projects and they have good weather-resistant as well.
Cedar is resistant to decay and insect damage and will not shrink or warp like other types of wood. pic.twitter.com/jvAD16p6iC— Rustic Fence (@OnlineFence) May 12, 2016
So, let’s answer some frequently asked questions regarding how to keep wood from warping on different occasions.
How To Keep Wood from Warping After Cutting?
Here’re the steps you can take to keep wood from warping after cutting.
- Wood layers align vertically
- Store wood in a clean, dry, cool area
- Supply plenty of ventilation
- Lumber should place on a flat solid surface
- Heavyweights should place on top of the wood to prevent warping
Following the above steps after cutting wood will prevent the wood from warping. The above methods help the wood to reach Equilibrium Moisture Content (EMC) by drying quickly.
This whole process takes 2 -3 days to complete. During the drying process wood should not be exposed to rain or high moisture environments.
How To Keep Wood from Warping After Painting?
Here’re the steps you can take to keep wood from warping after painting.
- Sealing the edges of the wood. Because edges are the areas that are highly exposed to the outside environment and they’re the area that highly exchanges water and moisture with the outside world and initiates the wood warping. Because wood is stressed out due to imbalances of moisture exchange rates all over the wood that leads to warping. By sealing those areas, their moisture absorption and releasing rates will slow down and prevent wood warping.
- Seal the whole area. After the painting is done, you can apply a protective layer all over the wood without missing any spots to build a permanent barrier to water between the outside environment and the wood itself. Before sealing check the moisture content of the wood and make sure it’s around the 8% – 10% range. Otherwise, if the moisture content is high, wood will start rotting inside. 8% – 10% moisture content is ideal for sealing. By sealing the whole area moisture no longer get in contact with wood and no warp will happen.
- Let the wood dry completely. After the application of paint, varnish, shellac, and other finishers, the wood has been exposed to plenty of moisture, and it tends to warp. By letting the wood dry completely, the water will evaporate, and the wood mostly will get back to its original shape by un-warping.
How To Keep Wood from Warping When Drying?
Here’re the steps you can take to keep wood from warping after drying.
- Allow partial drying to exchange moisture quickly and regain its original shape
- Avoid slow drying processes because they will warp the wood even more.
- Don’t do over-drying because over-drying will evaporate water excessively and the wood will shrink excessively. This can lead to wood cracking and splitting.
Green (freshly cut) wood can be over 50% water. As it dries out, uneven drying creates internal stresses resulting in some interesting consequences like this huge 3cm warp and twist. When green both of these pieces were perfectly flat. pic.twitter.com/REvhKm4ulp— Kam (@kamsar) December 31, 2019
So, that’s all we got under how to keep wood from warping with all the possibilities.
Did I cover all you wanted to know about: How To Keep Wood From Warping?
From this article, we have widely discussed how to keep wood from warping and what are the best 5 methods you can easily use to avoid wood warping. Those are the methods that woodworkers follow for any small or large woodworking project which work perfectly.
Furthermore, we have talked about how to fix warped wood with some pro tips to keep wood from warping. Those tips are so helpful for both beginner and advanced woodworker to protect their loving woodworks from moisture. Ultimately sealing the whole wood is the best option to get a life protected from warping.
Also, we’ve answered some frequently asked questions regarding how to keep wood from warping when painting, drying, and on other occasions as well.
Hope you have gained good knowledge about wood warping and what actions you should take to stop it. So, let’s head into your next woodworking project with this knowledge. Have fun in woodworking!