How to Make a River Table: Step-by-Step Guide

A river table is two live-edge wood slabs with a channel of epoxy resin running between them. It looks simple, but it is a long project with a few steps where a mistake costs you a lot of resin. This guide walks through every stage in order, from choosing dry timber to the final coat of finish, and points out where things usually go wrong.

The Process in Brief

Choose dry slabs and plan the layout.
Prepare the wood: remove bark, flatten if needed, fill cracks.
Build a level, leak-proof mould.
Seal the wood with a thin coat of epoxy.
Fix the slabs down and pour deep-pour epoxy in layers.
Wait for a full cure, then demould.
Flatten with a router sled or CNC.
Sand, finish and fit the legs.

Allow several weeks from start to finish. Most of that time is waiting for wood to acclimatise and resin to cure, and rushing either is the most common cause of a failed table.

Step 1: Choose and Dry the Wood

Popular choices are walnut, oak, elm, ash and spalted beech, because they have attractive live edges and strong grain. You can buy a single slab and rip it down the middle, then turn the two halves so their live edges face each other. That gives a bookmatched look and a natural river shape.

Moisture content matters most

Wood shrinks and moves as it dries. Epoxy does not. If you pour around a slab that is still wet, the wood keeps shrinking afterwards and can pull away from the resin, crack, or bow the whole table.

For furniture in a centrally heated UK home, aim for roughly 8 to 12% moisture content, ideally towards the lower end, since heated rooms dry out a lot in winter.
Air-dried timber straight from a yard is often well above that. Kiln-dried slabs are a safer bet.
Check with a moisture meter in several places, including the middle of the slab, not just the ends.
Bring the slabs indoors and let them sit in a similar environment to the final room for a few weeks before you start.

Prepare the slabs

Remove the bark. Bark usually loosens over time and traps air that bubbles up through the pour. Take it off with a drawknife, chisel or stiff wire brush, leaving the natural edge underneath.
Flatten the slabs if they are twisted or cupped, so they sit flat in the mould. The same router sled you use at the end works here.
Deal with cracks and knots. Small cracks can be filled with epoxy during the seal coat. Large splits can be stabilised with bow-tie (butterfly) keys.
Plan the river. Lay the slabs out, decide the river width at each end, and mark the final table size. Allow extra length and width to trim off after flattening.

Step 2: Build a Leak-Proof Mould

The mould is a shallow open box. The standard material is melamine-faced chipboard (melamine board), because it is flat, cheap and cured epoxy does not stick well to it. HDPE sheet is even better for release but costs more.

Building the mould

Cut a base a little larger than the finished table, plus side walls taller than the slab thickness. The Sheet Cut Optimizer helps you get the panels out of one board.
Cover every inside face with sheathing tape (often sold as Tuck Tape or house-wrap tape) or a wide polypropylene packing tape. Epoxy releases from these tapes. Overlap the strips and press them down firmly with no wrinkles.
Screw the walls to the base from the outside, through pre-drilled holes.
Run a bead of silicone sealant along every inside seam and smooth it into a small fillet. Let it cure fully before pouring.
Brace the sides. A full mould of resin pushes outwards, and long walls can bow.
Set the mould on a strong, flat bench and shim it until a spirit level reads true both ways. Resin finds its own level, so a sloping mould gives a deep end and a shallow end.

Test the mould before you need it

A leak is the worst failure in this project: resin finds the smallest gap and keeps running for hours. Some makers test with water first and then dry it thoroughly, others simply check every seam twice. Either way, put a plastic sheet under the mould and check it in the first hour after pouring.

Step 3: Seal the Wood

Wood is full of air. When warm epoxy soaks into it, the air comes out as bubbles that rise through the pour and get trapped as it sets. A seal coat fixes this.

Brush a thin coat of epoxy over every surface of the slab that the river will touch, especially the live edges and any cracks. Let it reach a tacky stage before the main pour, so the layers bond. A table-top or coating epoxy is fine for this. The Epoxy Resin Calculator can add a seal-coat allowance to your total.

Step 4: Choose the Right Epoxy

This is where many first river tables go wrong. There are two broad kinds of epoxy, and they are not interchangeable.

	Deep-pour (casting) epoxy	Table-top (coating) epoxy
Use	The river itself, thick castings	Seal coats, flood coats, coasters
Typical layer	Often around 25 to 50 mm (1 to 2 in) per pour; some products allow more	About 3 mm (1/8 in) per coat
Cure speed	Slow, often days	Faster, often a day to touch
Viscosity	Thin and runny, so bubbles escape	Thicker, self-levels to a coat
Heat build-up	Designed to stay low in thick sections	Can overheat badly if poured deep

The figures above are typical, not universal. Every product has a technical data sheet with its mix ratio, maximum pour depth, working temperature and recoat window. The data sheet always wins over any general guide, including this one.

Why pour depth limits matter: heat

Epoxy cures by a chemical reaction that gives off heat (an exotherm). In a thin coat the heat escapes. In a thick block it builds up, which speeds the reaction, which makes more heat. Pour too deep and the resin can get hot enough to crack, yellow, distort the mould, give off fumes or even smoke.

Never pour deeper than the data sheet allows in one layer.
For a deep river, pour in layers, and pour the next layer within the recoat window so the layers bond chemically.
Keep the room and the resin at the temperature the data sheet asks for. Most products are made for normal room temperature. A cold garage in winter slows the cure and can leave the resin cloudy or soft; a hot day speeds it up and makes overheating more likely.
Larger volumes heat more than small ones. Do not test-mix a big batch in a bucket and leave it standing; it can overheat in the bucket.

Working out how much you need

The river volume is the river area times the depth. Because the river is irregular, measure the narrowest and widest points and use the average width. The Epoxy Resin Calculator has a river table mode that does this, adds a waste allowance and a seal coat, splits the total into part A and part B by your kit's ratio, and plans how many layers your chosen maximum pour depth needs. Always buy a little more than the calculation; running short halfway through a pour is a real problem.

Step 5: Colour, Fix Down and Pour

Fix the slabs down

Wood floats in epoxy. If the slabs are not held down they will lift and drift. Common methods are screws up through the mould base into the underside of the slab (the holes get flattened off later), or bars clamped across the top of the mould onto the slabs. Place the slabs, check the river shape, and fix them before mixing anything.

Add colour

Mica powders give a shimmering, pearly look; liquid pigments or tints give solid or translucent colour. Clear resin with no colour shows the live edges best. Whatever you use, keep to the maker's maximum pigment amount, because too much can stop the resin curing properly. Mix a little colour into a cup of resin first, then add that to the main batch, so it spreads evenly.

Mix and pour

Weigh or measure part A and part B exactly to the stated ratio. Weight and volume ratios differ for many products, so use the right one.
Mix slowly and thoroughly for the time the data sheet gives, scraping the sides and bottom of the bucket. Fast mixing whips in air.
Pour slowly into the lowest part of the river and let the resin spread on its own.
A few minutes after pouring, pass a heat gun or small torch quickly over the surface to pop bubbles. Keep it moving.
Cover the mould loosely to keep dust off, and check for leaks over the next few hours.

Safety with epoxy

Wear nitrile gloves and eye protection and work with good ventilation. Uncured epoxy is a common cause of skin sensitisation: once you are sensitised, even small contact can cause a reaction for life. Read the safety data sheet for your product.

Step 6: Cure and Demould

Deep-pour epoxy can feel hard on the surface long before it is fully cured inside. Leave it for the full cure time on the data sheet before you demould or machine it. Machining soft resin clogs cutters and tears the surface.

To demould, remove the screws, take the walls off one at a time and lift the table from the base. Taped melamine usually releases with a little persuasion from wedges or a wide scraper. Where resin has crept under the tape, a sharp chisel or a router will clean it off.

Step 7: Flatten With a Router Sled

The cured table will not be flat. The resin surface has a meniscus at the edges, the slabs may have moved a little, and there will be drips. You need a flat reference.

A router sled is the usual hobby method. Two straight, parallel rails sit either side of the table at the same height. A carriage slides along the rails carrying a router fitted with a large surfacing (spoilboard) bit. You move the router side to side in overlapping passes, then step the carriage along, taking a shallow cut each time. If you have a CNC router big enough, it can do the same job automatically.

Router sled tips

Shim the table so it does not rock, then check the rails are level and parallel.
Take shallow passes. Hardwood and epoxy cut differently, and a deep pass can chip the resin or tear the grain at the live edge.
Flatten one face, flip the table, and do the other.
Use the CNC Router Feeds and Speeds Calculator for a starting rpm, feed and depth of cut for a surfacing bit. It includes Makita-style router dial settings.
Wear hearing protection and a dust mask. Surfacing makes a great deal of fine dust and chips.

Once both faces are flat, trim the table to final size with a track saw or circular saw against a straight edge, and rout or sand a small chamfer or round-over on the edges.

Step 8: Sand and Finish

Sand both the wood and the epoxy through the grits, typically starting around 80 or 120 grit to remove sled marks and working up through 180, 240 and on to 320 or finer. A random orbit sander with dust extraction does most of the work. Wipe off the dust between grits; scratches from a coarser grit show up badly in clear resin.

Common finishes are:

Hardwax oil: easy to apply and repair, gives a natural feel, and suits the wood. The resin will look slightly satin under it rather than glassy.
Table-top epoxy flood coat: a thin coat over the whole top for a deep, glossy look. Use a coating epoxy, not deep-pour, and follow its thickness limits.
Polyurethane varnish or lacquer: hard-wearing and available in matt to gloss.

Fit legs with threaded inserts so they can be removed for moving. Allow for wood movement across the width when you fix the top to any frame: use slotted holes or table-top fixings rather than gluing it rigidly.

Common Problems and Fixes

Problem	Likely cause	Fix or prevention
Bubbles in the river	No seal coat, bark left on, mixing too fast	Seal first, remove bark, mix slowly, pass a heat gun over the surface
Cracked or yellowed resin	Poured too deep in one go; overheating	Pour in layers within the data sheet depth
Soft or sticky patches	Wrong ratio, poor mixing, too cold	Measure exactly, scrape the bucket, keep to the working temperature
Gap between wood and resin	Wood was too wet and shrank	Check moisture content and acclimatise slabs before pouring
Slab floated	Not fixed down	Screw or clamp the slabs before pouring
Leak	Gap at a seam, tape lifted	Silicone every inside seam, check before and after pouring

Plan Your Pour

Work out resin volume, A/B split and layers, then the cutting data for flattening.

Epoxy Resin Calculator Router Feeds & Speeds

Frequently Asked Questions

How much epoxy do I need for a river table?

Multiply the river length by its average width and the depth, then add 10% or so for waste and a seal coat. A river 1,800 mm long, averaging 150 mm wide and 40 mm deep holds about 10.8 litres before allowances. The Epoxy Resin Calculator does this sum and splits it into part A and part B for you.

Can I use table-top epoxy for a river table?

Not for the river itself unless you pour it in many thin layers. Table-top epoxy is made for coats of around 3 mm. Poured deep, it can overheat, crack and yellow. Use a deep-pour casting epoxy for the river and save the table-top epoxy for seal coats and flood coats.

How deep can I pour epoxy in one go?

It depends entirely on the product. Deep-pour resins commonly allow around 25 to 50 mm per layer and some allow more, but the maximum pour depth on your resin's data sheet is the only figure to trust.

What moisture content should the wood be?

For indoor furniture in a heated UK home, roughly 8 to 12%, ideally towards the lower end. Check with a moisture meter and let the slabs acclimatise indoors for a few weeks before you pour.

How do I flatten a river table without a big CNC?

Build a router sled: two level rails either side of the table and a sliding carriage holding a router with a surfacing bit. Take shallow passes across the whole top, flip it and repeat on the other face.

Summary

Start with dry, acclimatised slabs, build a taped and siliconed melamine mould that is level and braced, seal the wood, fix the slabs down and pour a proper deep-pour epoxy in layers no deeper than its data sheet allows. Wait for a full cure, flatten with a router sled, then sand and finish. Patience at the drying and curing stages is what makes a river table last.

How to Make an Epoxy River Table, Step by Step