Casting GFRC with Forton VF-774 to create shower panels. Multiple GFRC panels of different sizes and shapes will be made from this single texture mat mold to produce furniture, countertops and more.
Step 1. Preparing the Mold
A level casting platform is built. The rolled Mold Star 30 mold is brought from the job site. The mold is checked to ensure levelness. Excess dirt is blown off with compressed air.
Step 2. Panel Layout
Four panels will be produced. The four panels will be made on different sections of the same mold. 0.5" (1.27 cm) thick PVC boards will be used as form walls. The walls for the first panel are laid in rough position. Bracing is nailed to the casting platform. The form boards are carefully squared to make the first panel. Matching form boards are nailed at the top and bottom of the mold.
Step 3. Mixing and Spraying GFRC Face Coat Mix
The components are assembled. Type 1 Portland Cement and silica sand are dispensed by weight. Dry components are premixed. In a separate bucket, the liquid components are premixed. Water and Forton VF-774 are added by weight. Plasticizer is added. Iron oxide pigment is added as a base color. The liquid components and pigment are premixed. The dry components are added to the wet and mixed. The sides and bottom of the container are scraped. Part of the face coat mix is poured into a "hopper" style spray gun. The spray pattern is tested before spraying onto the mold surface. The spray gun applies a consistent layer of face coat on the mold surface. Once applied to the entire surface, the first face coat is lightly brushed smooth. A second face coat layer is applied immediately after brushing. The face coat is allowed to stiffen until the surface loses some of its wet sheen.
Step 4. Mixing and Applying GFRC Backup Mix
A larger high shear mixer is used to process larger volumes of material. Forton VF-774, water and plasticized are added. Iron oxide pigment is added. The mixer is started. Sand is added. Cement is added. The sides of the container are scraped. AR Glass fiber is added. A thin first layer of backup mix is gently applied to the entire surface. A bubble buster is used to work out air bubbles. A second layer of backup mix is applied to the entire surface. The second layer is compacted. A final layer of backup mix is applied up to the full wall height. The final layer is compacted. AR glass scrim is laid onto the wet panel and gently worked into the mix. A small amount of backup mix is applied over the end of the masonry ties. Plastic sheeting is placed over the back of the panel. The plastic prevents excessive moisture loss and maintains heat of hydration to ensure a proper initial cure. The panel is allowed to cure for 12-16 hours. The mold is reset for the second panel. The second panel is produced. The second panel is placed next to the first for additional curing. The third and fourth panels are produced. All panels are allowed to cure for 7 days before staining.
Step 5. Staining and Sealing the GFRC Panels
A water based concrete stain was chosen for this project. An even coating is applied by brush and then allowed to dry. To highlight the wood grain, the stained panels are lightly wet-sanded. A wire brush is used to bring out the details in the deeper textures. Once the panels have dried, a water resistant sealer is applied. The sealer is worked into the surface with a foam pad and roller. The sealer's satin finish further highlights the wood grain. The panels are allowed to cure.
Step 6. Panel Installation
The panels are installed at the house. A cast iron shower pan is installed. The bottom real panel is the first to be installed. Each panel is dry fit in place. A thick bead of construction adhesive is applied to the panel. The panel is lifted into position and pressed firmly in place. Galvanized screws are driven through the masonry ties into the wall. The top real panel is glued and screwed in place. The left side panel is glued and screwed in place. A stud wall is built to support the right side panel. The right side panel is glued and screwed in place. A carbide tipped hole saw is used to bore holes for plumbing fixtures. Brown silicone caulk is used to waterproof joins between panels. The shower door is hung and adjusted. The door rail is mounted directly through the GFRC panel. The water resistant panels dry quickly.