Wood Warping, Bending, And Twisting

If you ever have asked why does wood bend or twist at least know you are not alone. It is a common frustration. The good news is it can often be fixed and I will give tips soon on how.

Yet first we need to know what causes this to happen. There are steps we can take to minimize this phenomena at the beginning to aid us down the road.

If you acquire new wood I will assume that it has been cured and is dry. The one exception to this is any pressure treated lumber.

There are different rules for this lumber as often it is purchased and used in construction rather quickly. This is actually a good thing.

For general woodworking or within wood art we often use cut and dried lumber as our go to. After purchasing wood if one wishes to store it there are some things to know I will detail.

Do not let your lumber go to waste.

Gravity Can Cause Wood Warp

For larger thick slabs there is less concern with wood warp when vertically standing the lumber. Yet for boards or planks they should be stacked horizontally.

It is best to use what is called stickers to separate planks as they are stacked. In this way the planks do not touch one another.

Gravity can be a major pain when storing wood vertically. The weight of a board is resting on one end.

As it is leaning on a wall this weight will eventually bow and warp the wood in that direction. If one stores wood vertically it is best to keep it supported from the top in some fashion.

When stacking horizontally gravity can also get you here. I prefer to overuse stickers adding as much support as I can when I use them.

If I do not have enough to go around then I prefer to use no stickers at all but lay planks one on top of the other. This is not the best way to do things long term though.

What purpose does the stickers have? Aside from providing support from board to board, it also gives space between them.

The purpose is to allow air flow around the lumber in the stack. This helps prevent issues with humidity and moisture thus averting wood warp.

Humidity Can Warp And Twist Wood

Humidity will always impact your lumber. If you store your seasoned wood then keep it indoors. It is best to try and have some kind of climate control yet not all of us can do this.

At least with it being away from outside elements is a major win.

The humidity that is in the air will always impact the amount of moisture that gets back into the lumber.

The more humid the air the more moisture will reach the wood. The more dry the air the better off you are.

Humidity is always changing. Sunny warm days will be different from cloudy and rainy. Summer to winter and then there is spring and fall as seasons transition.

It is forever in a state of change. So will be the moisture within the wood as it is relative to what is within the air.

This impact over time can have an effect on how the wood responds. Again stacking lumber horizontally with stickers helps and it can give an advantage.

Air flow matters. Even on humid days circulating air helps. Simply running a fan will aid in this circulation. These small factors play a big role in wood warp.

I will add here that if one uses nails or screws in wood art you may also be creating issues. As humidity and temperature cause wood to move, nails create unmovable fixed points.

Not only can nails or screws cause warp, but also crack or break the piece over time.

The Hidden Things That Warp Wood

The two issues above are the most common culprits for general carpentry. Yet within fine woodworking there are other elements which come into play.

This is especially true within wood art where higher degrees of accuracy are desired in cutting and wood carving.

There is a hidden component which contributes to wood warp and especially twisting few ever realize.

Early on in my art making days I began to learn this principle and it was rather surprising. The wood grain can be the culprit no matter how well stacked the wood may be or how dry the air is.

Impact Of Grain In Wood Warp

This aspect will not often affect general carpentry as much as it will fine woodworking. In carpentry you often are dealing with pine boards, plywood, or milled trim pieces.

It is not to say that it cannot impact these different lumbers but its scope is limited and can be tied to species of wood.

The lumber used in fine woodworking, especially when more exotic, will have a lot of grain variation. I will use lumber from small local mills that is rough cut live edge ranging from 5/4 to 12/4.

These cross sections of the tree has within it the most dense wood at its center and the outer edges are less dense.

Due to this cut the grain is not as uniform as when compared to a 2×4. Over time when wood of this nature is stored this inconsistency can cause wood warp and twists.

The more dense grains that are tight will cause the board to move with environmental variables more than regular milled lumber.

How Wood Grain Works And Contributes

Wood grains are fibers which grow yearly as the tree grows. It is in fact the tree growth itself. To keep this non scientific, these fibers bond with a natural “glue” which forms the wood.

As years go by and new annual growth occurs the old growth becomes a part of the inner tree.

With time, stress from wind and storms, damage, outside organisms attacking the tree, this wood grain becomes compromised.

While there is a natural difference in density from center to edge all lumber faces natural elements.

The center of the tree will hold the oldest growth and here its core strength can be found. The fibers here do not yield easily.

They can be so tight that when cut to thinner planks that it causes a natural curl to a board. This is a natural wood warp which is difficult to avoid.

The outer edges of the plank are less dense and are more flexible by design. A tree in the wind needs to flex and stretch.

Its grain on the outer portions of the tree act like a rubber band and then also as a spring. It helps deflect stress while its core maintains its integrity.

How This Translates To Wood Warp While Carving

In wood art I love spalted wood or other exotic variants. Yet these can also be the more challenging to work with.

Damage which has been caused to trees over time add other variables to how wood will respond when it is cut or carved.

In my designs many will be wall carvings in art. Often in my projects I will make a wood panel from rough cut lumber which will display this art.

Before it reaches the stage of carving first it will arrive at my cnc mill. Here it will be surfaced so that both sides are perfectly flat.

The problem comes in that as material is removed it is a very common cause of wood warp.

Beyond this when carving art into the wood there are times when this will also happen. Clearly it is not as a result of improper storage.

Rather it is the result of removing material from the surface.

As material is removed from wood you are altering the tension which is shared along its surface. From the dense grains to the more porous there is a relationship to how it holds its shape.

By carving the wood you are altering this relationship and thus the wood will respond in kind adjusting.

What takes place is not due to an error in your work or craftsmanship. A woods density can be different not only across a board but also through its center. This is especially true if the tree has ever dealt with high stress and later healed.

How To Adjust For Cutting Or Carving

There are times when a simple wood clamp can provide enough stability to finish a carving. Once done other methods can be used to correct the wood warp.

Yet if at all possible this simple solution may be enough to at least get that part of the project completed.

Often trouble shooting these issues begins before you ever make your first cut on the lumber from the start. In time one learns how to read the grain and assemble panels or cut to smaller boards to try and minimize warp or twists.

When joining multiple boards keeping the grain uniform in direction and how it flows is critical. These elements can at times make the difference in a panel being workable or unusable.

Once the panel or other object is assembled what a woodworker does is responsive rather than proactive.

Solving Wood Warp Or Twisted Lumber

Clamping and time is the tried and true method that will solve most ills. There will be times that the wood warp or twisted end is just too much to correct.

Yet typically applying pressure to reverse the bend and clamping will work.

When doing this for wood carving some thought needs to be put into the process. When applying pressure to reverse the bend in order to achieve correction do not over compensate.

You can create an issue where one begins to go back and forth trying to find that sweet spot in getting the board straight.

Reversing a bend and clamping is done in order to relieve stress within the grain. One can think of it in a similar way to breaking in new leather.

In the case of wood you are stretching its grain so that the portions which cause the bend become more responsive to our desires.

Steaming Wood And Bending

There is an altogether different topic which surrounds steam bending wood for a purpose that is unique to itself. With some of those methods one can immerse wood in water then manipulate to a shape then dry.

This is not what I am bringing to the table here and now.

In the past I have heard of some who have tried to use humidity, heat, and clamping to bend wood back to its desired shape.

When doing fine woodworking or wood art this is a really bad idea. The goal is to always keep our wood dry.

By purposefully introducing moisture into the grain you have created new issues. You might be able to get the wood to initially conform to what you need but it will not remain.

As the wood once again dries it will begin to warp or twist.

The end result may be worse than when you first began. Moisture introduces an unpredictable variable.

To control this variable one would need to control how the wood drys. As lumber will change in density at times from inch to inch, the volume of water it has absorbed will also be different.

In reverse as it dries some portions will hold more water than others.

General Lumber For General Carpentry

The standard rule of thumb is keep general lumber dry and keep it flat. Lumber from places like Lowes or others can also be clamped and bent back to shape in a similar manner as I have detailed.

Yet on a job site more often than not it is tossed aside for an alternative piece in the pile.

When it comes to pressure treated lumber it can often be best to use as soon as possible for construction. As it dries but is fastened together the structure will help prevent warping or twisting.

There will always be those stubborn boards which will need some work or replacement in time.

When storing pressure treated lumber all one can really do is provide all the support that one can. Generally speaking keep it stored outdoors but away from the rain.

Air flow is better than sunlight or heat to allow drying while minimizing warping.

When cutting there is rarely any issues as I have described with fine woodworking or wood carving. Carpentry is rather definitive in its measured cuts for structural purposes.

Yet there have been those times I have seen short cuts later bow or bend and people wonder why. It is all in the grain.