Before starting a wood project with Epoxy Resin it is important that you begin by prepping the wood first. As timber retains moisture, resin and water/ moisture react with one another, so it is important to seal the timber first to avoid this reaction from occurring during the pouring and curing process. Even if you are using timber that has been dried and/or fired there will still be a moisture content which is why we would recommend the sealing process.
As the viscosity of our Casting Resin Systems; U RESIN Cast & U RESIN OceanCast are very low, the resin will seep through the porous timber cracks that may not be visible to the naked eye. So by sealing the timber, it will create a good barrier between the wood and resin. When Epoxy Resin reacts with moisture it can cause the resin to create excessive amounts of bubbles, create a ‘frothy’ like texture, pull away from the edges of the timber, create a rippled texture on the surface and/or accelerate the cure time. With every different wood can bring on a slightly different reaction if the moisture content is still high, so it is important to ensure you don’t skip this step when working with timbers.
As you can see in the image above, we have provided a side-by-side comparison using the same Casting Epoxy Resin; U RESIN Cast, the same Purple Pigment; Eggplant and the same Merbau Timber (from Bunnings). Both were poured at the same time and were given the same amounts of heat with a Butane Torch during the pouring process. The only difference between the Epoxy Resin River pours is that the first one has been sealed with our U Coast Sealer. The second was poured straight in with no prepping or sealing first and ended up curing with excessive amounts of bubbles, even after giving the resin some heat during the pour.
Whilst many would suggest applying a thin coating of Epoxy Resin over the timber first, it is possible to cause de-lamination over a long period of time. The best method to seal timber before pouring a River Table or similar would be to use our U Coat Sealer. This is a single pack, water-based polyurethane sealer. By applying a few coats of the U Coat Sealer, this will create a good barrier between the wood and resin as well as providing better adhesion to the wood. Once the sealer is completely dry, your wood is ready to go for you to set up your mould and pour your Casting Resin in.
If you have already poured your resin and hadn’t sealed your timber prior and experienced some kind of reaction, it isn’t all bad news! Once the epoxy resin has cured, give the resin a light sand to expose more of the pits or holes created by the bubbles, and re-pour a layer of resin.
If you’re in Perth and want to learn more about the sealing process, we have Casting Resin Workshops where we create Resin River Serving Boards & Resin River Tables. You can find our classes.