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A river table needs a deep-pour (casting) epoxy, not a countertop or coating epoxy. The two look similar in the bottle but act very differently. Deep-pour resins cure slowly, so the heat from the chemical reaction can escape. Coating epoxies cure fast and, if poured thick, can overheat, yellow or crack. This guide compares deep-pour options on the specs that matter for a river pour and explains where a coating epoxy still fits.
What to look for
- Maximum pour depth per layer. This decides how many pours you’ll need. Your table’s slab thickness divided by the max depth gives the number of layers.
- Working time and cure time. Longer working time leaves more time for bubbles to rise. Longer cure means a longer project.
- Recommended temperature range. Deep-pour resins are often picky (roughly 65–80°F).
- Mix ratio. 1:1 is forgiving. 2:1 and other ratios need careful measuring.
- Clarity and UV resistance. This matters most for clear or lightly tinted rivers.
- Volume limits. Some makers cap how much you should pour at once, not just how deep.
Comparison
| Product | Max depth per pour | Working time | Mix ratio | Full cure | Ideal temp |
|---|---|---|---|---|---|
| EcoPoxy FlowCast | 0.5–1.5″ recommended; max recommended volume 30 L | Long (see TDS) | 2:1 by volume (2.3:1 by mass) | Multi-day (see TDS) | 68–77°F, ideal 72°F |
| TotalBoat ThickSet | 1/2″ per layer for river/slab pours (2″ for small castings <10 oz) | ~30 min @ 70–77°F (pot life ~10 min) | See label | 3–5 days | 65–80°F ambient |
| Stone Coat Countertop Epoxy (top coat only) | 1/8″ per application recommended; 0.25″ max casting | 45–55 min | 1:1 by volume | 7 days (TDS) / 30 days (product page) | 68–75°F |
1. EcoPoxy FlowCast — best for thick rivers in fewer pours
FlowCast is EcoPoxy’s casting resin for river tables and other thick castings.
Key specs (EcoPoxy FlowCast TDS v2.3):
– Recommended casting thickness: 13–38 mm (0.5–1.5″) per pour.
– Maximum recommended volume per pour: 30 L (about 7.9 gallons).
– Mix ratio: 2:1 by volume (2.3:1 by mass). EcoPoxy warns that deviating from the ratio can lower mechanical properties or cause incomplete cure.
– Working temperature: 68–77°F, with 72°F ideal. EcoPoxy notes it cures more slowly at lower temperatures and thicknesses, and faster with more exotherm at greater thickness and volume.
Why it’s a good fit: A 1.5″-thick slab can often be filled in a single pour (within the volume limit), compared with three layers using a 1/2″-max product. Fewer pours mean fewer layer lines and fewer days of setup.
Considerations: The 2:1 ratio needs accurate measuring. Long cures mean more time before demolding and flattening, so check the TDS for exact demold and full-cure times at your temperature.
- Manufacturer TDS: ecopoxy.com
- Product page: ecopoxy.com
2. TotalBoat ThickSet — best for controlled, faster-curing layers
TotalBoat (a marine brand) sells ThickSet as a deep-pour clear epoxy for river tables, slabs and castings.
Key specs (TotalBoat product page and instruction sheet/TDS):
– Max pour depth: 1/2″ per layer for river and slab pours. Small castings can go up to 2″ if under 10 fl oz of mixed epoxy.
– Layers at least 4 hours apart, with no sanding needed between layers.
– Pot life about 10 min, working time about 30 min, gel time about 70 min at 77°F.
– At 70°F with 1/2″ coatings: tack-free in about 6–8 hrs, sandable in about 24 hrs, light use in about 48 hrs, full cure in 3–5 days. TotalBoat suggests waiting 5–7 days before wet sanding or buffing.
– Ambient temperature must be 65–80°F for full cure. Apply at 65–75°F and 0–60% RH.
– TotalBoat recommends a thin seal coat on wood, cured before you add more epoxy. For heavy UV exposure, it suggests a urethane or varnish topcoat.
Why it’s a good fit: Shorter cures per layer mean you can finish a multi-layer river in a couple of days instead of waiting a week between pours. That’s good for small shops and tight timelines.
Considerations: A 2″ slab means four pours. The short working time means you should pour right after mixing. TotalBoat warns that exceeding 1/2″ can trap heat and cause waves, yellowing or cracking.
- Product page: totalboat.com
- Instruction sheet/TDS: support.totalboat.com
Where a coating epoxy fits: Stone Coat Countertop Epoxy
Don’t pour your river with a coating epoxy. Stone Coat’s own TDS lists a maximum casting thickness of 0.25″ and recommends no more than 1/8″ per application. Coating epoxies are the right choice for the flood coat over the finished, flattened table.
Key specs (Stone Coat TDS and product page):
– 1:1 by volume (100:90 by weight).
– Work time 45–55 min. Heat deflection 130°F. Shore D81.
– Max batch size 1 gallon. Application conditions 68–75°F, 55–65% RH.
– Stone Coat states FDA compliance for food contact (21 CFR 175.300) when fully cured.
– Full cure: 7 days per TDS, 30 days per the current product page. Follow the newer guidance.
– Product page: stonecoatcountertops.com
How to choose
- Slab 1.5″ or less and you want the fewest pours: a resin rated for 1–1.5″ per pour (FlowCast).
- Thick slab but you want shorter cure times, or a cool shop where you can’t control exotherm well: a 1/2″-per-layer product (ThickSet), poured in layers.
- Large volume: check the per-pour volume cap as well as depth (FlowCast: 30 L).
- Top coat: a coating or table-top epoxy at 1/8″ or less.
Use our river table epoxy guide and calculator to work out the total volume, then divide it by the max depth per pour to plan your layers.
Tips that apply to any deep pour
- Seal the wood first with a thin coat to stop bubbles coming out of the grain.
- Seal the form. Use melamine or HDPE with silicone or tuck tape at the seams, and level the form.
- Control the room temperature before, during and after the pour. Precondition both the resin and the wood to the target temperature.
- Measure exactly by volume or weight, as the TDS specifies.
- Mix slowly to avoid whipping in air. Scrape the sides and bottom.
- Pop surface bubbles with a heat gun or torch, held 6–8″ away and moved constantly (TotalBoat guidance).
- Wait for full cure before heavy sanding, flattening or finishing.
FAQ
Can I use deep-pour epoxy for the top coat? It’s possible, but it’s slow and runs off edges easily. Most builders use a coating epoxy or another finish for the top.
Why did my river turn yellow or crack? Usually because the pour was too thick or too large in volume for the resin, or the room was too hot. Both trap heat from the exotherm.
Do I need a pressure pot? Not for river tables. TotalBoat mentions about 50 psi pressure pots for bubble-free small castings.
Sources
- EcoPoxy, FlowCast TDS v2.3 (2023).
- TotalBoat, ThickSet product page and instruction sheet/TDS.
- Stone Coat Countertops, Countertop Epoxy TDS and product page.