Which woods warp

As I stand here looking down at my useless Lumber I ask myself one question. What causes warps in wood? The basic answer is that wood warps because of uneven drying rates within the wood fibers. As my boards had sat there throughout the summer.

The ones exposed to more air and heat near the outsides of the pile had dried in unexpected ways. This would caused the surfaces that dried quicker to shrink at a greater rate than the surfaces that are protected. Now of course the wood you are working with may have any and all of the above deformities.

This makes warp correction or use of warped wood very difficult. I had never lived in an area with high humidity. But dry. After traveling to Japan during their summer, the meaning became clear. We were out for a walk and it started to rain. I was so excited that it was going to cool down and we would have some respite from the baking cobble stones. It stopped raining. The cooler temp lasted for 6 minutes.

Then the whole place became a sauna. I literally wondered if this was how I was going to die. Choking on steam in the Bikan district of Kurashiki. While that may sound like a meaningless aside it does play into the factors affecting warping.

Below is a list of different factors that will affect wood warping. EMC is when the moisture outside and inside a piece of wood are at steady state. More ambient moisture will cause the wood to swell. Lower ambient moisture will cause the wood grains to shrink. This acclimation process can months. The below factors also will affect how long EMC will take. While it is not easy, it is possible to fix warped wood.

The main idea is to add moisture back to the wood and then clamp it into shape. That way as the lumber dries it is forced to a specific shape. Below we listed a few different forms. The steaming technique is utilized when warping wood on purpose. We will talk more about it below. OK say you went over the techniques above and decided that fixing that warped pile of wood was too much of a hassle. How do you use your goofy looking wood without too much extra work.

A lot of this will depend on the project you are building and the type of warp that has occurred. Let me give you an example. I was building a workbench. Because I was screwing them down on to a strut and then gluing them to straight boards on either side, I was able to ignore the warping.

Glue, screws, and some heavy duty clamps can work wonders. Different warping shown in the same piece of wood could be a sign of multiple problems related to moisture content. Some species of wood are more stable and less likely to warp or crack than others.

The following species are known to be relatively resistant to warping:. Department of Agriculture. Several factors affect wood warping, some of which are easier to control than others. Different types of warping also tend to be caused by different factors. So being able to link warp types found to particular causes helps in preventing future warping. Grain patterns can influence the way wood behaves as it adjusts moisture content. Sawing techniques used in processing the lumber can also influence warping.

An understanding of these can help you limit your risk of manufacturing warped wood products. For example, in a quarter-sawn board where growth rings are symmetrical, shrinkage will occur evenly and cup-type warping is far less likely. Poor saw maintenance and variation in saw speed can result in boards that are thinner on the ends than in the middle, which can cause bow-type warping.

Sawing so the grain is parallel to the edge of the board can help prevent crooking. The way you stack and store lumber is a major factor for how it will change as it adjusts to EMC. Some best practices for stacking and storage of wood include:. Placing heavy weights on a stacked lumber pile can also be helpful in preventing cupping. The wood also needs proper ventilation, which is best accomplished by spacing the material so all surfaces are exposed to the air.

Store your lumber in a clean, cool, shaded and dry location. If you're storing wood in an area with high relative humidity—80 percent or more—be sure it's wrapped in material that is impermeable to vapor. This prevents the wood from absorbing significant amounts of moisture from the surrounding air. High humidity should be a real consideration for those manufacturing furniture and other wood products in South China and Southeast Asia.

Kiln-drying is often used in manufacturing, as it gives the manufacturer more control over drying speed and degree. But all kiln-dried wood will acclimate to relative humidity of its environment. The main advantages of kiln drying over more passive natural drying are that kiln drying stops insect activity and sets the sap in resinous softwoods, which is especially important for wood used as building material.

Sealing the ends of wood can also help prevent warping caused by uneven drying. Cedar is also expensive and, depending on where you buy it, costs about the same as redwood. Wood shrinks and swells at a cellular level until it reaches equilibrium; this is known as "seasoning.

Most wood is kiln dried before using, but fir is often shipped uncured and is used that way. When uncured fir is nailed in place, it will undergo a shrinking and warping process, bending and yielding to its new location, and then settle into its new home without further movement. Wood will be stable against warping and shrinking if it is cut from the heart of the tree. You can check this for yourself by examining the grain pattern closely.

The straighter and tighter the grain, the more stability it will have. Specializing in hardwood furniture, trim carpentry, cabinets, home improvement and architectural millwork, Wade Shaddy has worked in homebuilding since Shaddy has also worked as a newspaper reporter and writer, and as a contributing writer for Bicycling Magazine.