Construct GFRC Hearth Mold

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Concrete Look With Venetian Plaster. Not What I Expected!

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What happens here

Cut the particle board base for the hearth to the full length and depth needed. Carefully trace the desired curved shape of the hearth onto the particle board. Use a jigsaw to cut out this curved shape. Attach wooden blocks or strips around the perimeter of the base, following the curved line, to create the walls of the mold. Use pre-drilled pilot holes and screws to secure these side pieces without splitting the particle board. Apply a thin layer of paste wax to all interior surfaces of the mold (base and sides). This will act as a release agent. Then, apply a thin bead of silicone caulk along the interior corners of the mold and use a custom-made tool to create a consistent bevel (radius) along the edges. This prevents sharp corners on the finished concrete. Allow the caulk to dry completely.

Goal: This step involves cutting particle board to size, tracing the desired curved shape of the hearth, and assembling the mold with support blocks and screws, then preparing it with wax and caulk for pouring GFRC concrete.

Tools and materials

Circular Saw with Track
Cordless Drill
Custom Bevel Tool
Hearing Protection
Jigsaw
Measuring Tape
Pencil
Rubber Gloves
Safety Glasses
Silicone Caulk Gun
Particle Board (Melamine-coated)
Paste Wax Minwax
Rags
Silicone Caulk (Dynaflex) Dynaflex
Wood Screws

What they say

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Hearth two things about the Hearth uh number one it has to be concrete based so it can match everything that's number one number two it can't be too thick therefore we're going with a different product that I've never used ever ever and I'm excited to try and I'm a little bit nervous it's called gfrc glass fiber reinforced concrete you're able to have the concrete look while being a lot stronger and you can pour it a lot thinner I got some instructions I got some products delivered first thing I do start building the mold all right [Music] I messed up because these notches here and this is radiused out that's what the Hearth is right now there's a radius it's not straight I miscalculated I miscalculated cutting this thing by an extra five inches so fortunately I have another piece left over I'll cut that and then we'll start measuring this again [Music] [Applause] I've got to cut out this section because the notches go it's like a wrap around hurt that's exactly what's there right now so I have to cover it uh and then got my radius traced out fingers crossed there's not gonna be too much tear out because this is going to be the bottom is going to be the the pretty side so once the mold comes out that voila that's what you're working with fingers crossed there's no tearups all right let's let's Boogie we did it oh man no tear outs no tears all right let's go [Applause] [Music] all right I measured out the pour is going to be inch and a quarter that's how thick the slab is gonna be I pre-drilled my pilot holes because with particle board and you're putting screws in these has a tendency of things going sour [Applause] all right the last hurdle that we need to overcome we're not out of the woods yet is uh getting this arch in without the particle board snapping and that's very likely to happen when working with particle board and trying to bend it it's just the territory that we signed up for oh Bubba we gotta we got a crack here um fortunately it's on this side it's halfway through nothing on this side um what are we thinking let's re-secure it here and then for hopefully it doesn't go further [Applause] okay so in order to prepare the mold I learned this trick from my buddy Mike from industrial maker if you haven't seen him he's the king of these gfrc Porters go check his channel out what he does is he first puts on a paste wax on below here and the reason why is for the second step when we bevel the corners here and then use a little fondant tool to create…

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