Creating a Rebound® 25 Brush-On Mold to Cast a GFRC Banyan Tree
of Cancun, Mexico, specializes in the design and construction of beautiful yet functional
architecture. Their list of clients includes many of the elite hotels throughout Central
America. Among their varied specialties, Pretecno is an industry leader in precast
concrete, including Glass Fiber Reinforced Concrete (GFRC).
Recently, Pretecno engineer Jose Hormiga developed a way to bring an organic feel to some
of the company's latest building projects. At the Condominios Quadra Alea in Playa del
Carmen, Mexico, Hormiga used Smooth-On's Rebound® 25 silicone rubber to mold
a 30 foot (10m) banyan tree trunk. GFRC reproductions were then cast and used as
decorative columns throughout a tropical resort.
1 - The freshly cut banyan tree prior to mold making.
2 - The tree must first be prepared to make it suitable for the mold making process.
3 - Preparation includes stripping residual bark, sanding and cleaning the surface.
4 - Deep undercuts and gaps are filled to make the mold making process easier. Care is taken to ensure the original shape is preserved. Filling in gaps and undercuts helps prevent a mechanical lock between the original and the rigid support shell.
5 - Once the tree has been cleaned and the gaps filled, Smooth-On's Super Seal® is applied to fill in pores and prevent possible cure inhibition of the Rebound® 25.
6 - 4 layers of Rebound® 25 are brushed on until a mold thickness of 3/8' (1cm) is achieved.
7 - Rebound® 25 is allowed to fully cure. A fiberglass and resin support shell is then created.
8 - Demold: Once the support shell has fully cured it can be removed followed by the Rebound® 25 mold.
9 - Rebound® 25 silicone is flexible and strong enough to be pulled away from the original without tearing. The Rebound® 25 mold reflects perfect detail captured from the surface of the original banyan tree.
10 - The flexible rubber mold is then seated in the rigid support shell.
11 - The Rebound® 25 mold is seated and ready for casting
12 - GFRC casting is done in layers. First, an initial spray coat of concrete is applied to the rubber mold.
13 - Glass fiber is chopped and applied into the mold behind the initial layer of spray concrete.
14 - Glass fibers will make the finished thin-walled castings extremely strong.
15 - Additional layers of concrete and glass fibers are applied until the desired thickness is reached.
16 - Concrete castings are allowed to cure. They can then be removed from the Rebound® 25 molds and prepared for installation.
17 - The GFRC column halves are joined around a structural support column using more GFRC to eliminate seams. Post-finishing and painting is done on site.
18 - Finished and painted castings look exactly like the original banyan trees, giving a truly organic feel to the Condominios Quadra Alea in Playa del Carmen, Mexico.
19 - The key to creating realistic castings of the banyan tree is to capture and reproduce the smallest detail. Rebound® 25 silicone rubber perfectly reproduces even the smallest wood grain from the original.
20 - The Rebound® 25 mold can be used many times for production casting of these architectural elements.
21 - The Rebound® 25 mold can be used many times for production casting of these architectural elements.