Wood tends to warp from exposure to moisture and heat. You must apply these same elements on the side opposite to the warping in order for the piece of wood to return to its original flat shape and be straightened effectively. In general, a minor deformation can only be corrected by applying heat and humidity. However, it is most likely that you will also need to apply pressure to the wood if it is a severe warp.
Steps
Method 1 of 3: Using the iron

Step 1. Wrap the wood with wet towels
Dampen one or two large towels and wrap them around the wood. Make sure to cover the entire warped area.
- The towels you will use should be large enough to cover all of the wood. You should choose towels or rags that can withstand the heat of an iron.
- When you wet them, you should soak them well and drain the excess water. They should be damp, but not too wet to the point of dripping.

Step 2. Place the covered wood on an ironing board
In addition, you can use another hard flat surface. The raised part should point up.
- The concave surface should face down.
- The surface you place the wood on should be rigid. In addition, it must be able to withstand the high heat of the iron.

Step 3. Heat the iron to its highest level
Turn on an iron and set it to the highest temperature.
- Wait two to five minutes for the iron to heat up.
- Keep in mind that the iron should be steamed, not dry.

Step 4. Press the iron onto the warped surface
You need to rest it on one end of the covered wood. Gradually slide the iron over the entire surface, applying even pressure to the warped area.
- You should keep the iron on each part for five to ten seconds before moving on to the next.
- Each point should overlap slightly so that you cover the entire wood.
- Do not leave the iron unattended on any part. It could burn the towel and the wood underneath.

Step 5. Repeat the process if necessary
You need to check the progress of the wood. If the problem has been corrected, you can stop at this point. If you still notice a bit of distortion, you should repeat the process until the problem goes away.
- After the wood is straightened, you need to turn off the iron and lay out the piece. You must let it dry completely before using it.
- This process is likely not to work on severely warped pieces of wood. If you don't see any progress after two or three attempts, try another method.
Method 2 of 3: Use sunlight

Step 1. Wrap the wood with wet towels
Dampen several large towels and wrap them completely around the warped wood.
- You have the option of using rags, sheets or towels. The material you use should retain moisture and be large enough to wrap around the warped piece of wood.
- Soak the towels in water, then drain them as much as possible. The material should be damp and not wet when wrapped around the wood.

Step 2. Expose the wood to direct sunlight
Place the wrapped wood in a warm area that receives plenty of sunlight during the day. The concave side (curved inward) should be facing down and the convex side (bent outward) facing up.
- You may need to place a tarp under the wood to prevent water from soaking the surrounding area.
- This method works best in hot, dry climates. However, it is likely not to be effective in humid, cloudy or cold environments.
- For best results, you should place the wood on a hard surface (for example, driveway or patio). You can place it on the lawn, but the process is likely not to be as effective if the wood is on a soft surface.

Step 3. Spray water on the wood as needed
Depending on the degree of deformation, you should expose it to the sun for two to four days. You should spray more water on the towels during this time to keep the wood moist.
- Just like in the previous section, you need to make sure that the material is wet and not soaked.
- The sunlight should heat the covered wood and encourage it to absorb moisture from the towels. Once he absorbs the wetness, he should start to sit up properly.

Step 4. Dry the wood until the warpage is corrected
This whole process can take several days depending on the severity of the damage. Check the wood regularly. Once it's straightened, you can remove the covers and let it dry.
- As soon as night falls, you must bring the wood inside. Keep it in a warm place at night with the affected part facing down.
- If you don't see any progress after a few days, you may need to try another method.
Method 3 of 3: Apply pressure

Step 1. Cover the wood with damp paper towels
Dampen several paper towels and place them on the concave (curved inward) surface of the wood.
- Absorbent paper is ideal for this method, but you can also use a thin towel moistened in hot water or standard paper. Moisten the material you will be using, but make sure it is large enough to cover the entire warped area.
- Rinse the paper towel with water, then drain it thoroughly. It should be damp when you place it on the wood, but not too wet.
- For this method, you should only apply the damp absorbent paper to the concave side of the wood. By concentrating the moisture on this side, you can correct the warping and return the wood to its original horizontal position. The concave side will absorb more moisture while the convex side (curved outward) will dry out.

Step 2. Place stretch wrap over the absorbent papers
Wrap several layers of this wrap around wood and damp paper towels. Then adjust and tighten the film.
- The stretch wrap should slow down the evaporation process, allowing the wood and paper towels to stay moist longer.
- Make sure the plastic wrap covers all sides of the wood, not just the paper towel side.

Step 3. Place the lumber in a clamp
You need to place it in this tool, and tighten until the warped area begins to straighten out.
You should work carefully as you adjust the clamp. If you tighten it too much, the wood may split rather than straighten up

Step 4. Leave the wood for a week
You need to keep it fixed and wrapped in a warm place for seven days.
- Check it regularly and remove it from the tool if you notice any signs of damage.
- The storage area should be as warm as possible during this first week. The ideal temperature should reach 65 ° C. However, if you can't maintain such a high temperature, the warmest room you have should do the trick for most purposes.
- You can keep wood warmer if you expose it to direct sunlight or a heat lamp. In addition, you can wrap it in an electric blanket or place it on a heating mat. Keep the wood warm for at least 6-8 hours a day.

Step 5. Remove the covers
After the first week, you must remove the wood from the clamp and remove the stretch film and absorbent papers.
- At this point you should let the wood dry completely.
- Check the progress of the deformation. If the problem has been corrected, the piece of wood will be ready to use as soon as it dries and you will no longer need to apply additional pressure.

Step 6. Apply additional pressure
If the wood is still slightly warped, put it back in the clamp and let it dry for 2-3 weeks.
- The temperature may be a little cooler for this step, but the ideal would be 25 ° C.
- Ambient air should also be dry during this step. Do not store wood in a damp room.

Step 7. Check the progress often
As soon as the wood has completely dried, you can remove it from the clamping tool and use it.