An Intro to Slab Furniture and Working with Slabs

When you hear “Slab Furniture” you may be wondering what exactly that means. If you’re a woodworker you know exactly what that is – but generally speaking it can be a very broad subject. And as far as making Slab Furniture, one can take many different approaches in many different directions. For the purpose of this article, I will be talking about Plain sawn slabs being used to make furniture. (Plain sawn, or plainsawn, is a method of milling lumber without repeatedly rotating the log. It is very common, especially when the desired lumber product is a live edge slab. A live edge slab is a piece of lumber with at least one [bark] edge.) Plain sawn lumber can be live edge, or straight line ripped (no bark edge) resulting in what is most commonly known as “a board” or “a plank.”

There are many differences between Plain Sawn and another common method of Quarter Sawn. However for the purpose of this article we will simple say that Plain Sawn is what you will typically see as slabs, and Quarter Sawn (or even Rift Sawn) would be a finer finished board that would be used for “fine woodworking”. (You’d see quarter sawn lumber at any hardwood dealer or even your local home center. If you have a [non live edge] table or other wood furniture, you will most likely see that being quarter sawn.)

So, let’s get back to the SLAB. Slabs are a very interesting and awe inspiring type of lumber. You can mill, or purchase, a slab in any species – and you will surely be amazed at the finished product…..and even during the building process. I personally love slabs that feature a “CROTCH” – yes, that’s right….I said I love crotches. A crotch is just a simple way of saying “the point where the tree splits into two or more branches/trunks – this results in a “Y” and the crotch is simply where the “Y” begins. In the Crotch, you are also going to see some “Crotch Figure”. (And defects, or characteristics other than the straight grain, is referred to as figure or figuring) The Crotch Figure is usually a very beautiful grain and can sometimes feature bark inclusions (bark inside the body of the tree) and you will usually see some “feathering” figure as well. The feathering is exactly what you’d expect, it resembles a feather along the edge of the “Y”.

Note: The picture to the left shows the base of a crotch. You can see that the “trunk” splits into two and creates a “Y” – the section you are looking at here is the crotch. (Insert dirty joke here) This may be a bad example picture but you can see several things. Look directly into the center of the crotch. The dark oval area you see is a bark inclusion. Directly to the right of this, we can see some feathering. And then on the left and right trunks we see some defects. (looks like cracking/splitting that has happened over time.) Then if you look at the edges you will see the live edge. So if we were to vaguely classify this it would be a “Live Edge Crotch Figure Slab. (Or something along those lines.)

After knowing a little bit about slabs and the things to look for, and hopefully accent in a project, let’s take this a step further.

As far as making furniture using “Slabs” you can do many, MANY different things. You can make tables out of one solid piece Slab, Or you can even join two slabs together and make a wider table top with two live edges. You can do this with “Book Matched” slabs (meaning that they are two slabs from the same log – slab A and the slab that was cut next, slab B). Book matched slabs are a great solution for making large table tops or other surfaces without the need for an extremely large log, or the even larger milling equipment. You can even add similar or contrasting “boards” or “planks” between the slabs to get an even larger surface. As far as “joining” the lumber together – a common practice is using something called biscuits, dowels or even floating tenons. This involves cutting/drilling into each piece to be joined together and using a piece of wood (biscuit, dowel, tenon) to aid in the glue up process and in some cases – they may add strength and rigidity to the joint. And, as an additional touch of elegance and character you can even add a Dutchman/Bow Tie/Butterfly (once the pieces are all glued together) to add additional strength to the joint. These can be any shape you wish, but are typically shaped like a bow tie. (once the [bow tie] piece is cut, a corresponding recess is cut into the surface being joined. Then the bow tie is glued into place. This provides additional strength to the joint.)

That last paragraph covered a lot and it’s easy to become overwhelmed. The important thing is to research the things you do not know and also TRY it. Whatever it is, try it and you will be amazed just how much you learn while you are doing it. Let’s look at a joined slab table top and make some of this make sense.

In the picture to the Right you will see two “Book Matched” slabs joined together and reinforced with Bow Ties (Dutchman is the technical term, also called butterflies) Let’s start with identifying how we can tell it is actually TWO slabs joined together. Let’s look at the edges on both sides. Can you notice the similarities in the shape of the edge? Looking at the end closest to us, follow the curves of the edge (look at the sapwood, the white edge along the bark) – you can see some similarities in the edge of the grain. Next let’s look at the center, along the golden colored section. You can see a very subtle line at the [front] end that continues through the top. These slabs were most likely cut after one side of the log was cut to remove the bark and sapwood, then the log was rotated 90 degrees and then proceeded with plain sawing. This would result in slabs with one live edge and one straight line edge. This is a very common practice in the process of milling slabs to be sold/used in pairs of “book matched slabs.”

These two slabs were glued together and most likely include some mechanical joinery such as dowels, biscuits or tenons – These are primarily used to aid in the glue up process by providing a registration point to keep the boards aligned while the glue is drying. We can see the Bow Ties very clearly as they are a contrasting color. If we were to look at them by themselves – we would see that the grain orientation is perpendicular to the grain of the table. This is important. As the wood grain expands and contracts throughout the changes in humidity and temperature (the changing of the seasons) the slabs may have a tendency to separate. With the grain of the Bow Ties running perpendicular to the slab grain – this will aid in maintaining the joint of the two slabs. (This is something that you can learn by experience, but I definitely encourage you to research this on your own. I don’t want to go into a lot of detail, but I also DO NOT want to over simplify this.) Wood movement is very real and can cause some issues if not properly planned for.

Note: Bow Ties can be added to slabs that are being used individually. It is very common to see splitting occurring in slabs. This is something that we definitely want to prevent from becoming worse and potentially leading to a destroyed or ruined product. Depending on the length of the split, you can determine the size of the bow ties and also how many to use and the spacing.

Another common form of SLAB furniture involves the use of Slab “COOKIES” – an easy way to define this is a horizontal cut of a tree stump. This would leave you with a round slab encompassed in bark. It would resemble a cookie. As you look at the picture to the left, it’s easy to see how this slab is cut. In this case, the cookie was used with some simple legs and made into a coffee table. Cookies provide a very beautiful finished product – which can be achieved with minimal tools and equipment. They are great for hobbyist and experienced woodworkers alike. You can spend as much or as little time refining the surfaces and finishing the cookie slab, and also in designing the base. You could use legs that are readily available at many hardware stores, or you can dive in further and design your own base or legs to achieve many different finished looks. Bow Ties are a great addition to cookies, especially to add in the rigidity and long term life. Since the cookies are a sort of cross section of a tree, cut horizontally – the exposed top is end grain. It is very common to see splits/cracks and it is important to handle these with care. As soon as you notice a split, you should work to remedy this. a common practice is certainly the use of the Bow Ties – another common practice is Epoxy or Resin. This is something that you should definitely research and look into – see what others have done and what has had the best results.

As with anything – it’s all about YOUR interpretation of the task at hand. Slabs, of all kinds, offer a GREAT opportunity for you to let your creativity shine. Try new things and don’t be afraid to fail. Fear of failure should never be a factor. Instead, be afraid of NOT TRYING. It’s only by trying new things, and thinking outside the box, that we learn new skills and expand the horizons of what is possible.

I hope that this has helped to provide some information regarding slabs and slab furniture. This is only the first article on the subject, and we will be covering this topic in more detail soon. I started this post to show some slab furniture projects I have done recently and the things I have learned, but I first wanted to explain some key terms and characteristics. Now that you have more of an understanding of what a slab is and some of the ways they are used for furniture – next time I will show you some of the things I have learned while working with slabs.

The Sneak Peak for the next article is the image up top. This Oak Slab bench was made for our home – an outdoor bench for our fire pit. It started as a warped, cupped, twisted slab and provided the opportunity to learn a lot. And I will tell you more about that in the next “SLABS” article.