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How To Build A River Table

Watch our tutorial on how to build a river table from start to finish here!

In this project we used EcoPoxy's deep-casting resin, FlowCast. It performs beautifully for deep pour river table projects and has a 2:1 mix ratio by volume.

We started the project with a slab of reclaimed poplar that came from a tree in our CEO’s front yard. Unfortunately, the tree had to be cut down because of the risk of it falling during a heavy storm, but we’re going to give it new life as a river table.

Prepare the wood

Make sure whatever wood you use is dried and seasoned. If you buy your live edge slabs from a lumber store, they should already have been kiln-dried.

Clean up any bark and sand off any loose material from the live edges. You need to create a good clean surface for the epoxy to bond to. Cleaning the surface also eliminates voids that could trap air bubbles during pouring, and it adds to the strength of the tabletop.

Once your slabs are prepped, you can cut them to the desired length. Make sure the ends and edges are square. We’re using a table saw, but you can do this with a mitre saw, track saw, or even a circular saw with a straightedge.

Prepare the mold

Cut the base and side pieces for your mold to your desired dimensions. We used melamine, but MDF or plywood will also work well. Make sure the sides of the mold are at least 1/2” taller than the thickness of the slab to avoid any overflows during the pour. Cover the pieces of your mold with sealing tape. We recommend using screws to put the mold together. This will help when it comes to demolding your project later. Apply a bead of silicone to the inside corners of the mold. You could also tape the edges but silicone is easier to apply and is better at creating a leak-proof seal.  Make sure you follow the manufacturer’s recommendation for cure time.

Preparing to pour your resin

With the mold is finished, it’s time to clamp down your boards. The wood would float in the epoxy otherwise, so this keeps it flat and in place. It’s really important you don’t screw the slabs from underneath. All epoxies experience a small expansion amount of shrinkage during the curing process. The slabs could pull apart if they aren’t free to move a little. That’s why clamping is best. Ensure that the form is level and as leakproof as you can make it. The last thing you want is a blowout. It’s also a good idea to put down a piece of polyethylene sheet below your mold, to ensure any blowouts end up on the sheet, and not on your floor.

Preparing the Epoxy & Pigment

The next step is to figure out how much resin you’ll need. In the past, that meant figuring it out with a formula and a calculator, but now we can use the handy EcoPoxy Volume Calculator.

Just figure out the average gap between the slabs and enter that as the width. Then enter your length and depth measurements into the volume calculator, and it will tell you the volume of FlowCast you need in gallons or litres. The volume calculator even includes an additional 5% in the calculated volume to account for resin that may fill any voids and cracks in the wood during the pour. In this instance, our average gap was 5.5”, the length was 50”, and the depth was 3”. So, when we plug that into the volume calculator that gives us 3.75 gal, or 14.2L. We always round up to ensure we have enough product, so for this table, we ended up using 15Lof FlowCast. It uses a 2:1 mix ratio by volume, and can be poured up to 1.5” in a single pour. Always mix the desired amount of resin with exactly half the amount of the hardener, and then mix until clear. Then we’re going to add the pigment. For this table, we will use one of our Metallic Color Pigments, called Caviar. We wanted the river table to be opaque so we will add about half of the 15g container of pigment. You could also use regular pigments for a solid colour, or even no pigment for a glass-like appearance. Once the epoxy is mixed, let it rest for 15 to 20 minutes. This eliminates a lot of the air bubbles.


Pouring & Curing

The next step is to pour the deep cast resin, making sure to fill every part of your table, including cracks and knots in the wood. Once the resin is poured, we want to pop any remaining air bubbles. We used a torch, but a heat gun also works. As you may have noticed, this pour is a lot thicker than the recommended 1.5” depth, but you can do thicker pours if you have proper heat dissipation. So, we will set up two fans to help dissipate some of the heat generated during the curing process. You only need to turn on the fans when the temperature approaches 35°C, or 95°F, which occurs around 6 to 8 hours after the pour. If you exceed 1.5” in a single pour, make sure you use an infrared thermometer to keep an eye on the temperature. Now we’re going to let it cure for a total 72 hours, then it’s time to unscrew the mold. Remove the sides and the back gently with a putty knife or a pry bar..

Finishing the River Table

You can finish the tabletop with a belt sander as we did or use a planer or even a router with a router sled jig. Once flat and smooth on both sides, it’s time to start sanding. Always start with a coarse grit and slowly increase to a finer grit. For this project, we sanded the wood all the way up to 220 grit. We sanded the epoxy section to a 320 wet sand, removing all the marks from the previous rounds of sanding. We wanted the table to have a satin look, so we finished it with two coats of Osmo Polyx-oil clear satin hardware oil finish. For a durable glossy look, you could always use our UVPoxy water clear coating resin as a final topcoat.

With the finish applied and cured, we’ve turned reclaimed wood into a beautiful one-of-a-kind coffee table that you’d be proud to display in your living room.