Short answer: use a true deep-pour casting epoxy whose published max pour depth covers your river (or plan layers), with low viscosity for bubble release and a UV stabilizer. Never flood a river with tabletop epoxy.
| Spec | What to check |
|---|---|
| Max pour depth | The maker's rating at a stated temperature and volume; plan layers if your river is deeper |
| Cure / demold time | Deep pours commonly take several days; colder shops take longer (cure time calculator) |
| Mix ratio | 2:1 and 3:1 are common; weigh if the data sheet gives weight ratios (ratio by weight) |
| Viscosity | Thinner resins release bubbles better in thick pours |
| UV stabilizer | Slows yellowing, which shows more in thick clear rivers |
| Kit size | Get the gallons from the river table calculator, then add 10–15% |
Also plan the form: melamine or HDPE boards, sealed seams, and a seal coat on the live edges so the wood doesn't release air into the pour.
Not for the river pour itself; tabletop epoxy is meant for ⅛–¼" coats and can overheat in thick pours. It is fine for the final flood coat.
Length × river width × depth in inches ÷ 231 = gallons, plus 10–15% for waste and soak-in.
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