Epoxy river table
The project deep pour resin was invented for. The volume is smaller than the arithmetic most people do, and the depth is well past what a coating epoxy can take.
A six-foot river table with a 200 mm channel takes about 18.1 litres of mixed casting resin, or 4.79 gal — not the length × width × depth of the whole form, because the two slabs displace most of it. It has to be a deep pour resin: the channel is far past what a coating epoxy will take in one go, and going over that ceiling is a heat hazard rather than a slow cure. Build the form, seal every joint and the slab edges, level it, and pour.
A river table is two live-edge slabs held apart in a form, with resin poured into the gap between them. It is the project that made epoxy a woodworking material rather than a craft one, and it is the reason deep pour resin exists as a separate product — nothing else in the craft asks for two inches of clear resin in a single pour.
It is also the project people most reliably get wrong twice: once on the volume, and once on the resin. The volume, because a river table is mostly wood — the river table, 6 ft below is a form holding 74.1 litres of space, and the answer is 16.5 litres, because the slabs displace the rest. The sum that works is the CHANNEL, not the table. And it stops working the moment the slabs are thinner than the pour: drop them to 30 mm under the same 45 mm pour and the resin runs over the top of the wood, taking it to 35.7 litres — 117% more, and $457 of resin nobody budgeted for.
And the resin, because 45 mm is 15 separate coats of table top / coating epoxy and 1 pour of deep pour / casting epoxy. The pour depth guide covers why that is a safety matter and not a patience one, and the calculator has a river preset that does this sum from your own measurements. If this is your first pour of any size, start at how to make resin art instead — a river table is not a beginner project.
What the river width actually costs
A 1.83 m form, 900 mm wide, poured 45 mm deep with 45 mm slabs. The only variable is how wide the channel between them is — everything else about the table is the same. Volumes include 10% wastage; the cost is materials at $90 a gallon, so substitute your own.
The three numbers that decide the pour
The form holds 74.1 litres of space and the slabs displace most of it, so what you are pouring is the channel. Measure it at several points along the live edge and average — the edge is wavy by definition, one measurement will be wrong, and the error compounds over two metres. Then add the 10% for what stays in the buckets, which on a pour this size is 1.6 litres on its own.
Inside a single lift of deep pour / casting epoxy, whose ceiling is 2 in. A thicker slab is not: a 3 in top is two lifts whatever the bottle says. In table top / coating epoxy this depth would be 15 coats, which is not a plan — it is a reason to buy the right resin.
Long enough to mix 18.1 litres in several buckets and get it all in, which is exactly why casting resin has it. Full cure is 7 days, and the table cannot be flattened, sanded or finished until it is there — plan a fortnight from pour to finished top, not a weekend.
What decides how it goes
A river table is a form with two slabs in it, so the volume is the form minus what the wood displaces — and the displacement is capped at the slab thickness. While the slabs are at least as thick as the pour, that reduces neatly to the channel times the depth. The moment they are thinner, it does not: at 30 mm slabs under a 45 mm pour the resin covers the wood as well, and the same table takes 35.7 litres instead of 16.5 litres. The calculator's river shape asks for the slab thickness for exactly this reason, and it is the input people skip.
Resin finds every gap and it finds them slowly, over hours, while you are not watching. Seal the inside of the form with tuck tape or packing tape (resin does not stick to it), silicone every internal joint, and seal the slab itself — end grain and live edge both — with a thin skim coat of resin the day before. An unsealed live edge releases air into the pour all night and leaves a line of bubbles frozen along the wood.
Wood floats, and a few litres of resin lifts a slab surprisingly easily. Screw the slabs to the form from underneath or clamp them across the top with a batten. A slab that has risen 2 mm during the night is not something you can push back, and it takes the flat reference face with it.
Resin levels to the horizon, not to the form. A form that is 2 mm out over two metres casts a river 2 mm deeper at one end, and once it is cured that difference has to come off the top of the whole table. Level the form itself before anything is mixed, and check it in both directions.
The look almost everyone is after is a translucent tint with depth to it, which is a very small amount of pigment — well under a per cent. Opaque colour at this thickness reads as a block of plastic rather than water. The pigment guide covers the loads and why more is not better.
A deep pour cures over days, and it will pass through whatever the room does at night. A garage that drops to 10 °C stalls the cure; a workshop that hits 30 °C in the afternoon accelerates it in a mass that is already the deepest thing you will ever pour. Somewhere steady around 21 °C for the whole cure is worth arranging.
Building one
A live edge is wavy by definition, so the gap varies along its length and an average is the only honest input. Measure at both ends, the middle and halfway between, and use the mean. On the table above, being 20 mm out on the average is about 1.6 litres of resin.
A thin coat of the same resin brushed onto the live edge and end grain seals the pores and stops them outgassing into the pour. It takes twenty minutes and it is the difference between a clean river and a line of bubbles trapped against the wood.
18.1 litres does not fit in one mixing container, and it should not — a mass that size in a bucket is a deep pour of its own. Mix in batches of a few litres, in wide containers, and have someone else mixing the next one while you pour. The pour should not stop, or you get a visible line.
Pouring straight down into the middle folds air in, and casting resin is thin enough that it will find its own level without help. Run it down one slab face or off a stick so it enters the channel rather than falls into it.
7 days before it is fully cured and 48 hours before the form comes off. Do not flatten, sand or plane before full cure: uncured resin gums the abrasive and machines badly, and the surface you make will move as the rest of it finishes.
The resin on this table is about $431 of materials, and it is a smaller share of the total than people expect once the wood is in. Widening the river from 100 mm to 300 mm triples the resin. The calculator has a cost view that takes your own kit price.
Size your own table
Pick the river preset, put in your form length, its width, the combined slab width and how thick the slabs are, and the calculator subtracts the displacement and gives the mix, the split and the number of lifts.
Open the epoxy calculator →Print the pour-depth card
Maximum pour depth and cure windows by resin type — the number that cracks a casting. Free.
Estimates, not advice. Every figure on this page is computed from published reference values and standard measures, so your own inputs, equipment and conditions will move it. Nothing here is professional advice — talk to a qualified professional before acting on it.