Sculptures made from fibreglass and resins have several distinct advantages over those made from concrete, bronze or other materials. They are significantly lighter, making them easier to transport and ship. Also, they are much more durable than concrete. Fibreglass sculptures can be placed outdoors, so they can be made much larger than sculptures constructed from other materials. Making a fibreglass sculpture is a time-consuming task, but it is a great way to create lightweight, long-lasting works of art.
Construct your sculptural model from modelling clay and coat it with petroleum jelly. Build a box that is 3 inches larger than your sculpture, and coat the inside of the box with paste wax.
Fill the box with 1 inch of plaster. Insert your clay model. Continue filling the box with plaster. Allow the plaster to harden for 30 to 45 minutes or until it is cool to the touch. Using a spoon or a palette knife, remove the clay from the plaster. Shellac the inside of the plaster mould and let it set overnight.
Brush paste wax along the inside of the mould. The paste wax should extend to the edges of the mould to prevent the plaster from sticking to the fibreglass.
Mix Bondo with its catalyst and add a small amount of fibreglass resin to achieve a paint-like consistency. Brush Bondo along the inside of the mould and let it set for 30 minutes.
Measure and pour fibreglass resin into a cup. Add 7 drops of MEKP to each tablespoon of fibreglass resin and mix. MEKP is a catalyst that activates the fibreglass resin and allows it to harden.Brush the fibreglass resin mixture on top of the Bondo. Lay squares of fibreglass matt along the inside of the mould, making sure that the pieces overlap. Brush additional resin on top until the fibreglass matt pieces are soaked through.
Allow the fibreglass resin to set up for 45 minutes, or until it is cool. Use a hammer and chisel to break away the plaster mould. The fibreglass cast can then be sanded, patched and painted.
Always wear rubber gloves when handling fibreglass matt. The fibres can cause intense itching if they come into contact with your skin. Bondo and fibreglass resin emit harmful fumes. Construct your sculpture in a well-ventilated area. MEKP is an explosive substance, so keep flames away from your work area when you are mixing and applying the fibreglass resin mixture.