Building the Structure
Planters need to hold the weight of wet soil and resist the outward pressure of root systems. While they don’t need to be as strong as a boat hull, they must be rigid enough not to bulge.
The Hand Lay-Up Process
The Skin Coat: After the gelcoat is tacky, apply a layer of resin and a layer of thin Chopped Strand Mat (CSM). This prevents the heavy texture of woven fabrics from showing through the gelcoat.
Wetting Out: Apply resin to the mat. Use a brush or wool roller. The white mat should turn transparent. If it stays white, it’s dry (weak). If it pools resin, it’s too rich (brittle).
Consolidation: Use the bubble buster roller immediately. Roll outwards to push air bubbles to the edge. This consolidates the fibers.
Bulking Up: For larger pots, add layers of Woven Roving for stiffness. Alternate Roving with Mat to ensure good adhesion.
Critical Reinforcement Zones
Corners
Rim/Lip
Bottom
Corners: Stress concentrates in corners. Always overlap your fabric layers at the corners. Do not just butt them together.
The Rim: The top edge is often used to lift the pot. Reinforce it with an extra strip of roving or even embed a core material (like cardboard or foam) to create a thick, rigid lip.