Product Description

RiverCast is an clear epoxy system designed specifically for woodworking casting applications.  It produces ultra-clear casts with minimal bubble entrapment.  Use RiverCast to make beautiful river tables or to fill large inclusions in wood substrates. For small voids, use MirrorCast, and for complete instructions, download our handy PDF here.

  • Fill voids up to 1.5” thick in a single pour
  • De-aerates rapidly
  • Contains no VOCs
  • Easy 2:1 mix ratio
  • Use with CastFX Dry Metallic Pigments or Liquid Colorants to create stunning effects!

BONUS: All 7.5 and 15 Gallon kits of RiverCast come with a free Jiffy Mixer to make mixing a breeze! (Mixer will be automatically added upon checkout).

$ 264.95
Mix Ratio by Volume100:50
VOC Content0 g/L
Mixed Viscosity260-290 cps
Minimum Curing Temperature70° F (21° C)
Working Time @ 70° F (21° C) 3 hours

Directions for Use:


How Much RiverCast For The Job

Measure the length (L) x the average width (W) x the average depth (D).


L x W X D = total cubic inches. From the total cubic inches see which RiverCast kit meets your needs. It’s advisable to pad your estimate by 10% to ensure that enough material is available.

RiverCast Kit SizesCubic Inches
1.5 Gallon Kit346
7.5 Gallon Kit1,730
15 Gallon Kit3,460

Working Conditions:

RiverCast performs best when the ambient conditions are between 70-80°F. Acclimate the wood substrate and the RiverCast Epoxy 24 hours before use. Cool conditions, below the recommended temperature range, will cause RiverCast to not only cure significantly slower, but the likelihood of entrapping microbubbles is more likely in the finished product. Higher than recommended temperatures could cause RiverCast to cure too rapidly resulting in possible warpage or discoloration. See the Resources tab for additional information



Mix a small batch of RiverCast Epoxy. Using a disposable, natural bristle brush, apply a thin coat of the epoxy to the walls of the void. After 10-15 minutes, brush on another thin coat of RiverCast. Make sure that the interface between the non-stick material and the wood substrate are coated with RiverCast. This creates a seal, preventing the RiverCast from leaking once the large pour is undertaken. Allow the seal coat to cure overnight.


Measuring And Mixing:

Measure 2 parts Resin (Part A) with 1 part Hardener (Part B) into a clean graduated mixing container. RiverCast can be mixed efficiently with a drill and paddle mixer. Avoid spinning the drill up at too high a speed, as this will introduce excessive air to the mixture. It’s advisable to also use a paint stick to scrape the sides and bottom occasionally as you mix. Carefully scrape the sides and bottom to prevent unmixed material from spoiling the cast. Unmixed material will not harden sufficiently and remain soft.


You know you’re getting close to fully mixed when the mixture has turned from cloudy to clear. Once it’s clear, RiverCast generally requires a bit more mixing to fully incorporate the components. After you’ve mixed a batch, double check to make sure that there is no thick buildup on the sides or the bottom of the container. See mix time chart under the Resources tab.



When filling a void, pour RiverCast just to the surface. If multiply batches were mixed, use a paint stick to gently merge them together in the void. Allow it to settle for 5-10 minutes. Then slowly add more material, slightly overfilling. The RiverCast should be domed and proud of the surface. Use only the material that freely pours from the container. Wipe up any epoxy that has spilled out onto the surface, as thin films take extended periods of time to cure.


Within the first 30 minutes check the fill level. If the RiverCast has dropped below the surface, carefully refill to a slightly overfilled level. Additional pours can be done once RiverCast has cured overnight. No sanding is required between pours within 72 hours. After 72 hours, lightly sand with 220 grit sandpaper before adding more RiverCast.


Surface Preparation For Finishing:

Best results are achieved by allowing RiverCast 7 days to fully cure before sanding and finishing. Sand RiverCast with a hard-sanding block and 120-150 grit sandpaper to flatten the surface to the surrounding wood substrate. A cabinet scraper can also be implemented. Once the epoxy surface is flat with the surrounding substrate, use an orbital or random orbital sander. Sand the wood substrate, blending into the epoxy filled area. Over sanding RiverCast can dish the surface. Occasionally, check the top with a straight edge to gauge progress. Further sanding is dictated by the type of protective finish coating selected. You will note that the RiverCast surface will lose its clarity after sanding. However, once a protective coating is applied, depth and clarity will return. See sanding recommendations below for the appropriate grit selection prior to applying the top coat. Be sure to follow with the correct grit sequence. Skipping grits can result in scratches showing through the top coat.


MirrorCoat and other System Three Epoxies – Sand to 150 grit


Polyurethane- Sand to 220-320 grit


Lacquer- Sand to 320-400 grit


Oil finishes- Sand to 400-600 grit


Top Coats:

Most coatings are compatible with RiverCast, but it’s advisable to pretest to ensure that expectations are met. RiverCast can be used in conjunction with all System Three Epoxies and top coats. Like most epoxies, RiverCast can be used for exterior application, but a quality UV top coat is needed to protect from sun exposure. See System Three Clear Finishing of Outdoor Wood for more details.


SDS Part A | SDS Part B



RiverCast Application Guidelines


Working Conditions:

In the winter months, RiverCast may be exposed to very low temperatures during transit. In some cases, the Part A can turn cloudy from the exposure to cold temperatures. If the Part A is cloudy, it will need to reconstitute the material. Heat the Part A only in a water bath at approximately 120°-130°F throughout. Once the Part A returns to a clear state, no further heating is necessary. Allow the material to return to room temperature before beginning your project.


Building a Form:

When fabricating a river table or when filling large inclusions that go through the entire slab, it’s necessary to build a framework to contain the epoxy. Plastic sheet goods or smooth, rigid plywood covered with clear packing tape work well for constructing a non-stick form.

In most instances, large slabs are not perfectly flat. The form material when mated against the wood slab may have intermittent gapping along its length. Gaps can be closed by drilling pilot holes through the non-stick material. Use screws that easily pass through the pilot for maximum effectiveness. Once the form is complete, use a carpenter’s level to level the slab in both directions.



Pre-sealing the walls of the void prevents large air bubbles from forming in the epoxy. After curing overnight, the seal coat will likely be tacky. The RiverCast can be poured over the tacky seal coat without issue.


Before filling the void with RiverCast, inspect the seam between the wood substrate and the non-stick material for gaps.


Mix Times:

Drill and Paddle Mixing

1 Gallon3-5 Minutes
2 Gallons4-6 Minutes
3 Gallons6-8 Minutes

Hand Mixing

1/4 Gallon3-5 Minutes
1/2 Gallon3-5 Minutes
1 Gallon4-6 Minutes

For batches larger than 1 gallon, use a drill and paddle mixer. The Jiffy mixer brand is an excellent choice for mixing larger batches of RiverCast. This mixer is available on the System Three website or most paint stores



The surface of RiverCast will initially be filled with bubbles from the mixing process. These bubbles will dissipate within 4-6 hours. Also of note is the surface in this timeframe will have a skin-like appearance. This too will dissipate within 4-6 hours.

If constructing a river table, it’s best to keep the slab contained within the form for a full 7 days. In the early days of cure, the epoxy is underdeveloped and could possible warp or bend if not fully supported. Keeping the slab supported and contained as it cures greatly minimizes potential unwanted movement of the wood slab/epoxy.

Casting resins are designed to cure very slowly. This design feature allows the end-user to pour large volumes of epoxy without experiencing a runaway exothermic reaction. Because of this slow cure, it can take RiverCast multiply days to harden.

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