To hard coat polystyrene with a low-cost alternative to fiberglass and resin, you can use a combination of Hessian fabric and a water-based adhesive. Here are the steps you can follow:
Materials:
- Polystyrene foam
- Hessian fabric (also known as burlap)
- Water-based adhesive (such as PVA glue or Mod Podge)
- Scissors
- Paintbrush
- Sandpaper
- Paint (optional)
Instructions:
- Cut the Hessian fabric into pieces that are slightly larger than the area you want to hard coat.
- Apply a layer of water-based adhesive to the polystyrene foam using a paintbrush.
- Place a piece of Hessian fabric on top of the wet adhesive, making sure it is smooth and free of wrinkles or bubbles. Press down on the fabric to ensure good adhesion.
- Apply another layer of adhesive on top of the Hessian fabric, saturating it completely. Make sure to work out any air bubbles or wrinkles as you go.
- Repeat steps 3 and 4, applying additional layers of Hessian and adhesive until the desired thickness is achieved. You may want to let each layer dry before adding the next one.
- Once the final layer has dried completely, use sandpaper to smooth out any rough or uneven areas.
- If desired, paint the surface of the hard-coated polystyrene foam with a suitable paint.
This method can produce a relatively hard surface that is more durable and resistant to damage than plain polystyrene foam. However, keep in mind that it may not be as strong or durable as fiberglass, and it may not be suitable for certain applications where a high level of strength is required.