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Pressure Gluing Wood

November 13, 2018Olen Murriel

Woodworkers use clamps to secure wood joints tightly as the glue dries. The clamps keep the boards perfectly aligned while maintaining the desired measurements. It is advisable to apply the right amount of pressure on the boards. Applying excess pressure can easily deform the wood or squeezes the glue from the joints.

There are various types of clamps in the market. It is important to select the right clamp for your project. Some clamps are difficult to adjust thus making it difficult to regulate the amount of pressure applied to the wood. Most spring clamps are non-adjustable in nature. Spring clamps are good at securing a joint tightly. However, their design prevents you from setting the right amount of clamping force on the joint. Only use this type of clamp where other models can’t work.

Most woodworkers prefer using a bar-style clamp. This clamp gives you flexibility in terms of the size and type of wood you can use. Bar-style clamps are highly adjustable and you can easily regulate the pressure applied on the wood. You can secure smaller joints using a grip-style clamp since it is lightweight and single-handed. On the other hand, the long adjustable bar clamp is perfect for holding larger joints and wide panels.

Having the right clamp doesn’t guarantee clamping success. One important thing in clamping is the type of glue and how you apply it on the joint. Always ensure that you have used the right glue. Avoid glues that are meant for rubber, plastics and other materials. It is recommended that you evenly apply the glue on the joint. You can do this by using a brush or a glue roller. Both tools are ideal for spreading glue across the joint. Some glues can be applied on one mating surface while others have to be applied on both surfaces. You should also check if the glue has to set before clamping. Read instructions on how to apply glue.

Sometimes the joints can twist while clamping the wood. This is one of the main problems that clamping beginners experience. The solution to this problem is to alternate the position of your clamps on the wood. When you change the placement of one clamp, it counteracts the force applied by the other one. You can consider placing one clamp on top of the panel while the other one underneath. Alternate the position of your clamps along the length of the joint. This method keeps the joints perfectly aligned provided each clamp applies an equal amount of pressure.

Manually tightened clamps should be tightened 80 percent initially on each side before applying the appropriate amount of pressure. This prevents the wood from shifting and opening the joint in some loosely attached spots. Excess initial pressure squeezes out most of the glue on one side. This is problematic since the surface will lack enough adhesive to make strong bonding when even pressure is applied and the spot re-opens.

Some beginners apply excess glue on the joints before clamping. Excess glue is unnecessary and it can cause some clamping problems. Excess glue takes more time to dry and clamping pressure can squeeze it out when joining the two panels. If the glue is squeezed out of the joint and you let it dry, you have to remove it during finishing. Dry glue is difficult to remove and some glue removal equipment will cause scratches on the wood. This affects the quality of your product due to the uneven surface and unwanted patches of excess glue.

Moisture is another cause of un-smooth wood surfaces. Wood tends to lose or pick up moisture depending on the humidity of the surrounding air. Moisture causes localized swelling along the joints. For this reason, you should apply glue within a few minutes once you finish preparing the wood surface to create strong joints. Hardwoods swell and shrink more than softwoods. Therefore, you should apply glue on such joints immediately to prevent localized swelling. Thin pieces of wood are highly porous and this property facilitates drying. For this reason, the time allowed to prepare and glue thin wood is short. You can also eliminate this problem by applying the right pressure on the joint.

The clamping force required when gluing wood also vary depending on the type of wood. Hardwoods are denser than softwoods and you should apply more clamping force. The tight grain pattern in a hardwood makes it too strong and you will find it difficult to close the gaps. Softwoods can be compressed uniformly with little force. Softwood species such as pines and maple need less force to squish the touching spots and close larger gaps to an acceptable level. Most woodworkers find it easier to glue softwood species.

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