How do you guys get those clean radius board formed walls without blowouts?

I’ve had better luck using 1/2-inch or 3/8-inch cedar boards instead of standard thickness lumber for tight radii. If you’re trying to force a 2x6 into a curve, you’re just fighting physics. The trick is **back-kerfing**—running the boards thru a table saw to make vertical cuts every inch or so on the hidden side. This allows the wood to flex without snapping and keeps the face looking like one solid piece once the concrete hits it. And for the bracing, stop trying to make straight walers work on a curve. You need to cut your walers out of double or triple layers of 3/4-inch plywood. Use a template to cut the exact radius into the plywood, then stagger the joints. This creates a rigid, curved spine that prevents the flat spots you’d get with straight lumber. It’s way more reliable for holding the pressure at the bottom of the pour.

To secure the base without turning the footer into swiss cheese, I ussually run a **kick-plate** or a shoe. Fasten a 2x4 plate to the concrete every four feet or so and use horizontal spacers to push against your form bottom. If you can't drill at all, you can sometimes wedge against the existing rebar cage, but you have to be careful about shifting your steel and compromising your coverage. Consistency in the grain comes down to using a thinner finish material over a structural "bendy-ply" backing. Use 3/8-inch cedar over 1/2-inch radius-grade plywood. This gives you the strength to hold the wet weight while ensuring the texture stays uniform across the whole arc. Just watch your seams. If the boards start to gap, a little bit of clear silicone in the joints goes a long way toward stopping the fins that happen when slurry leaks out.

That plywood spine idea sounds like a lifesaver for the blowout worry. I'm wondering about the actual stripping process though. Since thinner cedar is more fragile, do you guys use a specific type of form oil to make sure the wood doesn't splinter off and stay stuck in the wall? I’ve heard some guys lightly char the wood with a torch to harden the surface and pop the grain, but I don't know if that's overkill for a beginner. If those tiny fins do happen, how do you even sand them down on a curve without flat-spotting the texture?

On the stripping side, definately skip the cheap oil. Use a high-quality reactive release agent. It reacts with the free lime in the concrete to form a soap-like film, wich is a godsend for thin cedar. If you use standard oil on 3/8-inch boards, they’ll suck it up and get mushy, leading to that splintering you're worried about.

Also, pre-drill every single hole and use trim-head screws. If you try to nail those thin planks on a tight radius, the tension alone will split the ends before you even pour. It takes longer but saves the finish and keeps the grain crisp.