Intro: Black Walnut Slab and Black Epoxy Coffee Table (with Cocobolo Bowties)
This coffee table was a commission project and I am very happy with how it came out! The walnut has its flaws, but the cocobolo bowties and epoxy made it into a beautiful piece of furniture. As you can see the Walnut slab that I started with had a lot of defects and didn't look very pretty to start with. Sometimes, getting a slab with some imperfections means you can get it for a lower cost. I knew this could be something beautiful when I was done so I bought it!
Step 1: Check Out the Full Build Video on My YouTube Page!
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Step 2: Flattening and Prepping the Slab
I am very fortunate to have a Supermax drum sander. I started working on the slab by flattening and sanding both surfaces. Fortunately, despite the cracks, it did not have much twist or warp to it. That made it much easier to flatten and ensure that the top and bottom are parallel to each other. In the past, I have flattened slabs with a router flattening jig (video which is less expensive and still effective.
Step 3: Squaring Up the Ends
Both ends had latex paint on them to help with drying. I used my homemade door board and circular saw to trim the first end. Then I used a measuring tape to get the other end parallel and trimmed it as well.
Step 4: Prepping the Cracks and Live Edges
I wanted to clean up the crack as much as possible so the epoxy would be able to flow when I poured it. I used strips of sandpaper, chisels, files, Scotch-Brite pads… just about everything I could think of. A combination of things helped but the Scotch-Brite pads were probably the most helpful! I also used a 60 grit flap disc in an angle grinder to clean up the live edges. I try not to change the shape of the live edges, just clean up the gunk that had built up and get it ready for more sanding and finishing.
Step 5: Bowties or Butterflys?
Whether you call them bowties or butterflies or something else I cut a couple of bowties out of cocobolo wood on the bandsaw and sanded them before cutting the corresponding joint in the slab. This immediately helps to stabilize the slab before adding the epoxy.
Step 6: Carving the Bowtie Joints
I hold my bowtie in place while I trace it with a mechanical pencil. You can also use a marking knife. Don't forget to mark the ends of your bowtie to correspond with where they go on the board. I used 1/1-2/2 but use whatever you like A/A-B/B etc. just dont get them mixed up. When I have my pencil line established I go over it with a 1-inch chisel bevel in towards the material that will be removed. The chisel doesn't go in very deep just 1/8 of an inch maybe. I remove most of my material with as big a Forstner bit as will fit. I clean up those chips then remove more material with a trim router and ½ inch straight bit . An Up-Spiral router bit would probably work better. Finally, I use my fancy Harbor Freight chisels and work my way outward removing little bits of material up to my outline. Don't try to remove too much material at once or you might not end up with a tight fit. Sometimes I use a ½ inch chisel sometimes ¼ inch. Also, be careful with testing the fit of your bowtie as it is difficult if not impossible to remove it sometimes. When I feel like I will have a nice tight fit I put glue in the bottom of the mortise and around the outside of the bowtie and hammer it in place with a soft mallet. If it's not perfect, edges can be filled in with wood filler, or a mixture of glue and sawdust or in my case I used a little bit of the epoxy to fill the gaps around the bowties.
Step 7: Pouring Epoxy
I used this table-top epoxy: Pro Marine Supplies
And this black pigment: ComposiMold
I mixed a two-part epoxy in a disposable container and added TWO DROPS of black epoxy pigment PER ounce. I have learned by sad experience that not all epoxies can be mixed by weight. Maybe everybody already knows that… but it's best to measure it ounce for ounce to make sure the mixture is one to one. After mixing thoroughly for two minutes I poured in my first layer of epoxy. I let this drive for over 24 hours then repeated the process with another layer of epoxy which brought it up to the surface of the slab. In total I only used around 12 oz for this project.
Step 8: Scraping and Sanding
I removed a lot of the epoxy with a card scraper. I had left my bowties proud of the surface so there was also a lot of sanding with 80 grit sandpaper. Then I moved up to 120 grit and finally 220 grit sandpaper. Use a shop pencil to draw lines on the surface so that you know which areas have not been sanded and don't go over areas that have been sanded. I used a 1/8 in roundover in my trim router on the two ends and sanded the ends as well. I don't do a lot of sanding on the live edges because I like the rough look of them. But if I have scratches I go over them with 120 grit sandpaper.
Step 9: Wet Sanding
I wet sanded the epoxy with 500 grit then 1000 grit sandpaper. I experimented with even higher grits than that, but I was okay with how it looked after 1000. In the end the satin Arm-R-Seal finish left the epoxy with a matte finish.
Step 10: The First Coat of Finish
I used a tack cloth to remove all of the sawdust. Then using a foam brush I applied my first coat of General Finishes Satin Arm-R-Seal. Before flipping the board over I dry out my brush and sponge up as much of the Finish as I can. I don't want to leave any pools on the surface. After this coat dries I sand it with a high grit sandpaper. Usually 300 or 400 is okay but I used 1000 because of the epoxy. You can also hit it with very fine Scotch-Brite pads instead. The Scotch-Brite pads are especially effective on the live edges.
Step 11: Branding My Logo
I have a branding iron with my logo. After I remove the first layer of finish I burned the logo onto the bottom of the table. I hit that with 220 grit sandpaper until it looked good and applied the second coat of finish.
Step 12: 2-3 or More Coats of Finish
I usually find 3 coats of General Finishes Arm-R-Seal to be just perfect. I finished the bottom of the table first then flip it over and set it on painting triangles to finish the top. Deal with any drips on the edges before finishing the top. If they dry they can leave lines or drips that don't look good. While the foam brush is still mostly dry I go over those drips to blend them into the live-edge. After finishing the top look around under the edges again to make sure there are no drips. If you find any sponge them up from underneath. Go over the surface with your mostly dry foam brush and then leave it to dry!
Tip: I put my foam brush in a ziplock bag and leave it in the fridge. I find foam brushes are usually good for all three coats of finish this way, then I throw it away after the last coat.
Step 13: Burnishing and Buffing
After the last coat has dried for at least a couple of days (I usually wait longer) I burnish the surface with just a plain old piece of cardboard. This has the same effect as using a high grit sandpaper but without the risk of leaving any sanding lines. It knocks down all the nubs and leaves a smooth surface for buffing.
I use a mixture of Minwax paste wax cut with one or two ounces of mineral oil per can. Apply liberally with a cloth and then buff either by hand, with a Rotex sander and sheepskin , or buy a cheap polisher from Harbor Freight. Any of these will do the job.
Step 14: Hairpin Legs
I used these hairpin legs
I used a combination square , large carpenter's square , and tape measure to make sure all of my legs were lined up correctly. I pre-drilled with a self-centering drill bit then drove in screws to attach the legs. The kit I bought came with the screws as well as some plastic feet to prevent scratches on wood floors.
Step 15: Done!
Here are some pictures of what it looks like outside as well as in the client's home. It was very nice of them to contribute pictures after taking the table home!
Thank you very much for checking out my Instructable! There is a full build video on my YouTube channel Hubbard's Handmade!
Feel free to ask me any questions here, on my YouTube page, or on my Instagram page!