Resin Calc

River Table Epoxy Calculator

A river table is three pours, not one. Enter your slab and channel once to get the seal coat, deep pour and flood coat separately, plus what to buy for each.

River Table Calculator

Slab
in
in
River channel
in

Measure the width every 6 to 10 inches and average it. Live edges are never straight.

in

The channel is assumed to run the full length of the slab.

Pour stages

Deep pour resins are usually 2:1. Coating epoxies are usually 1:1.

What to buy

Total Epoxy Needed

683.4fl oz

Deep pour resin · 2:1

512 fl oz

A 341.3B 170.7

Coating epoxy (seal + flood) · 1:1

171.4 fl oz

A 85.71B 85.71
Seal coat
34.29 fl oz
Deep pour
512 fl oz
Flood coat
137.1 fl oz

How to Measure a River Table for Epoxy

Most people who run short on epoxy did not get the formula wrong. They measured a live edge as if it were a straight line. A river channel is an irregular shape, so the number that matters is the average width, not the width at the widest point.

  1. 1

    Measure the channel every 6 to 10 inches

    Work down the length of the slab and write down the gap between the two live edges at each point. Follow the twists rather than measuring straight across the table. Add all the measurements together and divide by how many you took. That average is what goes into the calculator.

  2. 2

    Use the thinnest slab for depth

    If your two slabs are not the same thickness, the epoxy only has to fill to the level of the thinner one before it starts overflowing. Measure the thinner slab and use that. If you are pouring flush to the top, channel depth and slab thickness are the same number.

  3. 3

    Account for the form, not just the wood

    Epoxy fills whatever the form holds, which includes any gap between the slab and the melamine base or the side rails. If your slabs are cupped or the edges are rough, add a little to the average width rather than trusting a tight measurement.

  4. 4

    Add a waste allowance

    Resin clings to mixing cups and stir sticks, raw wood absorbs a little, and forms occasionally leak. Ten percent is a sensible default and it is already applied in the calculator. Running out halfway through a deep pour leaves a visible line that cannot be sanded out.

Why a River Table Takes Three Separate Pours

A finished river table is normally three different applications of epoxy, and two different products. Calculating them as one lump is the most common reason a shopping list comes out wrong.

Seal coat

A thin coat brushed onto the raw wood inside the channel before the main pour. Bare timber holds air in its pores, and when the deep pour covers it that air escapes as a stream of bubbles that cure in place. Sealing first traps the air. This uses a small amount of coating epoxy, typically a 1:1 product.

Deep pour

This fills the river channel and is the bulk of the material. It needs a low exotherm casting resin, usually mixed 2:1, because a thick mass of standard coating epoxy generates enough heat to crack, yellow or boil. Check the maximum single pour depth on your data sheet and set it in the deep pour epoxy calculator, which will tell you how many layers you need.

Flood coat

The final coat poured over the whole surface once the river has cured and the top has been flattened. It covers the wood and the resin together, so it is calculated from the full slab area rather than the channel. This is coating epoxy again, so it comes out of the same product as the seal coat. For a coat over an area with no channel, use the epoxy coverage calculator.

Common River Table Mistakes

Using coating epoxy for the deep pour

Table top epoxy is formulated to cure fast and hard in a thin layer. In a two inch channel it overheats. The result is cracking, amber discolouration or a mass of tiny bubbles, and there is no way to fix it other than cutting it out.

Pouring deeper than the product allows

Even deep pour resins have a limit, commonly somewhere between two and four inches. Exceeding it produces the same exotherm problems. Pour in layers and let each one reach a tacky cure before adding the next.

Mixing by volume when the label says weight

Resin and hardener have different densities, so a ratio by weight is not the same ratio by volume. Getting this backwards leaves soft or sticky patches that never fully cure. The epoxy weight to volume calculator converts between the two.

Forgetting the flood coat in the budget

The flood coat covers the entire slab, not just the river, so on a wide table it can use as much epoxy as the channel itself. Working it out separately avoids an expensive second order partway through the build, and the epoxy cost calculator will price the kits.

River Table Epoxy Questions

How much epoxy do I need for a 6 foot river table?

It depends far more on the channel than the length. A 72 by 30 inch slab with an 8 inch average channel at 1.75 inches deep needs roughly 615 fl oz of deep pour resin for the river, plus around 200 fl oz of coating epoxy for the seal and flood coats. Enter your own measurements above for an exact figure.

Do I need a seal coat on a river table?

It is strongly recommended for raw wood. Without it, air trapped in the timber escapes into the deep pour and cures as a band of bubbles along the live edge. The seal coat uses very little material relative to the problem it prevents.

Can I use the same epoxy for all three stages?

Usually not. The deep pour needs a low exotherm casting resin, while the seal and flood coats want a faster, harder coating epoxy. Some brands sell a deep pour resin that can also be used thin, so check your data sheet before assuming.

How deep can I pour epoxy in one go?

Deep pour resins are commonly rated for two to four inches per layer, and coating epoxies for a quarter inch or less. The exact figure is on your product data sheet. Enter it in the advanced options and the calculator will tell you how many layers your channel needs and how much to mix each time.

Should I calculate the river and the flood coat together?

No. They use different products at different mix ratios, so a combined total cannot be split into Part A and Part B correctly. This calculator keeps them separate and gives you the shopping figure for each product.