Joining Wood Without Nails
For the purpose of this discussion we are speaking of how to join two boards lengthwise. This is using the long grain edge of a board not the end grain.
There are different methods of accomplishing this task without nails or screws, yet I will deal with the two most common methods and which is better or preferred.
End grain joining is another beast altogether. Typically two boards are never joined at the end in order to make them longer. If boards are to join at the end grain normally a finger joint or box joint of some kind is used.
In some cases if one desires to join two wood pieces end to end you may need to look into Japanese woodworking. Friction joints such as the kanawa tsugi are designed for this purpose.
When joining boards long grain to long grain lengthwise, you will find most commonly either a biscuit joint or the boards have simply been glued together.
Here enters the long debated issue of which is better. Is it wrong to simply glue two boards edge to edge, or should a biscuit joiner be used?
Biscuit Joining History And Application
Before the advent of modern machinery different shops had their methods of joining wood. Concepts such as tongue and groove were evolved early on for the desire to join wood in a semi permanent way for homes.
The Mortise and Tenon Joint is probably one of the oldest forms end grain jointing in woodworking. It is not until 1969 which we see real standardization of the biscuit joint come into play.
A man by the name of Karl Steiner developed a hand held machine that would play off of loose tenon joinery.
By utilizing an object called a wood biscuit that would fit into two boards which had been cut to accept this object, this allowed the boards to be joined accurately.
The added benefit to this method is the strength it offers to the wood joint. It maximizes the amount of glue which can be used across more surface area because of the wood biscuit being inserted.
This method became the new standard for wood joinery on boards which were joined long grain edge to long grain edge.
There is no doubt that this method is far superior to simply gluing two long edges together to make a wood panel. With time it came to be that if this method was not used then a woodworker was not doing proper work.
This method absolutely has its place yet it is not the be all end all of wood joinery.
To use this method requires that you have a biscuit joiner. This tool will cut slots into the wood where the biscuit is placed. You simply add glue and then clamp into place.
Yet where does this excel and where does it fail?
Benefits And Failure Of Biscuit Jointing
Here you can read an article which details many of the problems and failures of biscuit joining. Yet understand this can become a heated debate among some in the woodworking community.
When it comes to the argument of adding strength to the joint, some say it does little in this area. They cite that there is no real evidence to the fact.
Yet I disagree with that camp. I do believe it adds strength to the joint if only for the fact that there is more surface area for the glue to form its bond in the wood joint.
Wood glue works into the fibers of the wood. The more area this glue is exposed to the more grain it has to bond with.
It is simply logical that a biscuit would allow for the wood glue to penetrate into more grain to strengthen that natural bond. I really cannot see how the argument can be made otherwise.
The argument of its necessity is another matter altogether. I am not with those who believe that it must be used in all wood joinery.
In fact there are many cases where its use is a waste of time, energy, and effort. If the boards are thin and will not be load bearing, then there is no real purpose for using a biscuit joiner.
With thin boards there is little it can do to help with accuracy of the joint. In actuality you risk potential exposure of the joint when the purpose is for it to remain hidden.
Within wood art using a biscuit joiner will often create problems and is a failure, at least this is the case for me.
When wood carving I do not want to carve into a wood panel to find the biscuit as part of the artwork. This is a very bad thing to have happen.
If I am making a memory box then the box joints I use provide more strength when glued than any biscuit or tenon joint could ever offer.
When making wood art, the artist needs to be mindful of maximizing the wood canvas preventing any carving from exposing internal structural jointing methods.
Clearly these methods do not fit with the majority of my needs and cannot be used. So what is the preferred method that allows for strength to still be obtained?
Joining Wood With Glue Only
To accomplish this is rather easy. You apply glue to the edge of a board then push them together. Hold in place with a clamp and allow to dry and preferably cure for 24 hours. Remove the clamps, and if a good wood glue such as the Titebond series is used, then the boards are joined.
If one were to look online at wood forums or other “how to” pages you will see many cry out against this method. These voices herald from older times of wood joinery when materials were less refined than they are today. Nevertheless the glue only method does have its limitations.
To understand the why behind using this method one must know the wood glues that are on our modern market.
In the modern world of woodworking the glues which we have access to will form a bond which is stronger than the wood itself. At least this is the claim by the companies who make the glue and this needs to be discussed.
In terms of its function for wood art there is no better way for joining wood boards. Art rarely needs much structural support in terms of load capacity.
There can be exceptions to this yet in my artwork it has never been needed. When carving art the wood joint never causes an issue within the art itself, and this is a major factor in my use of this method. The benefit of using glue only far outweighs other options.
Despite the arguments for or against this method I have personally tested its strength in my studio. I have taken wood panels and smashed them to the floor as well as hitting them with hammers.
Each time the breaks which occur take place within a weaker portion of the wood itself rather than the glued joint. Woodworkers with their theories online are all nice and wonderful, yet real testing is where the truth is found.
I never want any of my work to go out of the door being inferior. Some pieces are more delicate than others by nature. Due to this the structure which holds the wood art together, it must be solid and secure.
If joining wood in this way is inferior to some for the purposes of my uses, as well as others in my industry, I have proof to say that mindset is dogmatic.
How Strong Is Wood Glue?
The strength of wood glue is relative to how it is used. The statement that it is stronger than the wood itself is not completely true, but it is close.
Wood gains its strength from the fibers which bind to each other. This natural element creates a strength which in reality cannot be truly replicated with glue only.
Glue gains its strength not from the glue but its ability to bind to these wood fibers. Here is where joining two wood boards lengthwise edge to edge will gain its strength along that line.
In real terms it is about the surface area the glue has along that line to form a bond within the material.
Nevertheless if used properly the wood glue offered today can do wonders. Where it excels is in joining boards can be found along a same line with no angle.
This is not limited to long grain panel making. Here once cured the bond will hold with such tenacity that the board will break at a weak point in the wood before the glue gives way.
In this case I would say that it is indeed true that the wood glue is stronger than the wood itself. If pressure is applied to the board it will hold as it disperses that pressure along the line of the joined grain.
This allows for pressure to be taken away from that joint and placed more evenly into the whole of the board or panel. Yet in what cases is this not true?
Where wood glue will fail is on any project where the glue itself is the anchor point receiving the load.
When that pressure cannot be transferred into the wood grain you have a problem. An example of this can be a chair leg which has been glued taking the weight of someone sitting.
The glue itself is not strong enough to support continued use even if the leg is glued into a pegged hole of the chair. Additional support structure is needed.
Angles at or less than 90 degrees present more problems when loads are consistently applied. For generations of woodworking this is why the mortise and tenon joint has been used with a binding of some kind.
Additional support to these angles especially for things like furniture help to relieve stress as it spreads a load more evenly across the structure.
Should You Join Wood Boards With Glue Only?
The answer is, it depends. Understanding what glue can and cannot do is important. If the end product will carry a sustained load, or a repeated on and off load over time, it may not be desirable.
This of course depends on the thickness of the wood and the load which will be used.
For wood art typically there is never a load applied. Panels of this nature where artwork is cut into the wood are for display purposes and will never have an issue.
Light shelving for objects which will not cause any substantial load are also perfectly fine. In these cases I would never hesitate to join edge to edge with glue only.
If you were to attempt this with heavier pieces of lumber which would make a dining room table you will have serious problems. Perhaps sooner than later in fact.
In these cases it is suggested you use a biscuit joining method of some kind.
How To Make The Wood Joint Seamless
I like simple methods. The key to making a wood joint disappear is easier if you use wood from the same cut off the log. When placing the boards together edge to edge you are looking for the best match in color and grain texture at the point of joining.
If the two boards come from different portions of the same tree it can become more complicated. This is still more desirable than if the two boards came from a different tree even if of the same species.
If coming from different trees the greatest success will come from the very generic boards you will find at places such as Lowe’s or Home Depot.
Wood sourced from those locations come from tree farms where the trees are not given enough time to create any real unique features within the grain itself.
Oak will look pretty consistent from board to board just as will maple. Obviously wood which has more character will present a problem in this case.
Nevertheless wherever you get the wood from when joining wood together you want the transition from one board to the next to be as clean in appearance as possible.
After you have glued and clamped allow to cure before moving on to the next step. I would advise having a wet rag to remove the excess glue which will escape the wood joint in order to keep that portion of grain clean saving headache later.
After the glue has cured you may experience places where the wood curled or bent. It may be the edge which is joined did not sit flush.
Personally I love to use my cnc mill to remedy a world of small issues yet not everyone has this ability. Sanding with a circular disc sander will do wonders at making these joints disappear though.
To straighten the new jointed wood panel or boards you can gently bend back into shape as you need with clamps, bracing, and time.