How to Glue Boards Together Without Warping

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Gluing boards without warping can be a very difficult task because of the nature of the wood that contracts and expands. It can lead a glued-up board to start curving that can degrade the structure of your final product.

In this article, we’ll discuss the best method to glue boards together without warping. You can use this method to make glued-up panels that will stay flat and you’ll be able to use them for any type of woodworking project.

What is Wood Warping?

Wood that has been deformed because of the change in moisture levels is called warped wood. The fibers contract in different parts of the wood as the moisture leaves and it can lead to deformation.

It happens when the humidity level or moisture content in the surrounding air is different from what wood possesses.

A piece of wood will continue to warp until it reaches the EMC (Equilibrium Moisture Content). Wood can also absorb moisture if the humidity levels in the surrounding air are higher than what it possesses and it can also lead to warping.

There are some other factors as well that contribute to wood warping including temperature, airflow, uneven finish, sunlight, grain orientation, and wood species. Wood can work just from aging.

Thicker wood species take a longer time to lose or absorb moisture, which also means they are less prone to warping.

Types of Wood Warping

Wood warping types include the following:

• Cup: Cupping happens when your board deviates from a straight line. The edges across the width of the board can be either lower or higher than the center.
• Kink: It usually happens when a small part of the board forms a crook because of a knot.
• Twist: This warp type takes place when the four corners of the board have been deformed and are no longer in the same place.
• Vain: This type of warp takes place when the board gets deformed along the length of the wood’s edge.
• Bow: It means your board has deviated from its flatness lengthwise.

How to Glue Boards Together Without Warping

The following steps will allow you to glue boards together without needing to worry about warping.

Supplies You’ll Need

• Glue
• Glue Brush
• Bar Clamps
• Sandpaper
• Water proof sealant
• Anti-warping Agent

Step 1: Choose Wood Type Carefully

While any wood type can warp, some wood species are more prone to warping than others. Wood that comes with open grain has more tendency to warp than close grain. 

The wider the grain, the more space between wood fibers, increasing the possibility of shrinking. Softwoods usually have wider grain than hardwoods.

The tendency for a board to begin warping not only depends upon the wood species but the way the board was cut. Even hardwood boards are prone to warping if they have been cut from the outer side of a tree, as they have a wider grain.

We recommend you choose boards made of any of the following species of wood. Not only will they minimize warping but they’re also easy to use in all types of DIY small wood projects.

• Redwood: This wood species has a straight wood grain pattern that prevents warping. In addition, redwood also possesses natural oils inside that keep it from shrinking.
• Cedar: It is one of the best wood species to prevent cracking and warping that happens because of moisture. It’s extremely dense and also has a relatively straight wood grain pattern.
• Fir: It’s also a great option to prevent warping, once it dries out and has similar moisture content to the surrounding environment.
• Pine: You can also use boards made of pine as it undergoes very little warping or shrinking.

Step 2: Prepare Boards

Other than selecting the right wood type, choosing boards that come with as straight grain as possible is also important. If you have not yet bought boards, make sure that you avoid the ones that have the grain running diagonally from end to end.

Additionally, if you have boards wider than six inches, cut them in half. That’s because the wider the boards the more the risks of warping. You will want to rip the boards on a table saw, although you could use a circular saw for rip cuts if you’re really careful.

After cutting a board, flip one of the halves so that one is facing down and the other is facing up. It’ll balance out the stresses of the boards in the glued-up panel and minimize warping.

Step 3: Apply Glue

Pick up the first board and apply glue on the edge that you need to attach to the other board.

Make sure that you don’t apply an excessive amount of glue. That’s because it contains water and can cause warping if applied in a high amount. 

We also recommend you use a glue brush on the board’s edge so that the glue can get into the pores of the wood. Repeat the same process for the second board and attach them together.

Step 4: Attach Bar Clamps

Use high-quality bar clamps with strong bars and jaws so that they can hold attached boards in place.

Space the bar clamps evenly across your attached boards and secure them properly. Avoid over-tighten the clamps because it can damage the boards. 

You can also use a spirit level to ensure your attached boards are perfectly flat. Additionally, make sure that bar clamps are not more than a foot apart to apply even pressure across the panel.

Step 5: Let Boards Dry

Don’t remove your attached boards from the bar clams until they are thoroughly dry. 

Typically, wood glue takes about 24 hours to dry, but you can check the user’s manual of the glue you used to find out the exact drying duration.

Step 6: Apply Sealant

Once your attached boards are thoroughly dry, remove them from the bar clamps and use sandpaper gently to smooth the joint, if necessary. After that, apply a sealant on all sides of the board panel. 

Buy a high-quality sealant to apply on your board panel to make it moisture-proof. Not only will it keep the water away, but it’ll also protect the finish of your board panel.

Different sealants can take a different amount of time to dry out and you’ll need to check the manufacturer’s instructions to find the exact duration.

Once the sealant has dried, you can use your board panel for the project you’re working on. Use the same method to glue together as many boards as you want without warping.

Storing Glued-Up Boards

If you have some extra glued-up boards that you don’t currently need to use, make sure that you store them in a dry and cool place. The spot you should choose for storing these boards should also be away from direct sunlight.

While they’re treated well to prevent warping, it can still happen due to prolonged exposure to humidity, moisture, and warm temperatures. Your best bet is to store them in a room that has plenty of ventilation and doesn’t have any appliance that produces heat.

Make sure that you lay your boards flat and they also need to be vertically aligned. We also recommend you place heavy weights on top of your boards to prevent warping.

Final Words

It’s possible to glue boards together without warping as long as you go with the right species of wood and choose boards that have already reached their EMC. 

We hope this step-by-step guide will help you understand the right way to glue up boards and prevent warping so that you can complete your woodworking project effectively.