Quadra Fire Pit

TWO: CASTING

Video Overview

Step 1 – Spray the Face Coat

  • The face coat can be sprayed with a GFRC sprayer, and either the Spray Blend or the Casting Blend can be used.
  • Supporting the form on saw horses and rotating it as you spray will make it easier to spray the larger surfaces.
  • Spray the coats on thin and build them up as they begin to dry. If you spray too much on at once, it will slump.
  • Any vibration can also cause the concrete to slump down, creating a runny surface.

Step 2 – Chip Brush

  • After the first coat is completely sprayed, use a chip brush to gently force the concrete into the edges of the form.

Step 3 – Mix the Backer

  • A fibrous backing blend will give the piece more strength than just the face mix or casting mix alone.
  • Press the mix into the form by hand, one pad at a time. Spread the concrete out as you lay it up, or it will slump down.

Step 4 – Flatten the Top

  • Continue packing the form until the walls are about 3/4″ thick.
  • Trowel the top edge flat to minimize grinding later.
  • Leave some of the concrete hanging over the edge to help keep the walls from slumping.
  • Let the concrete cure for at least 24 hours, and then move on to the next step: Demolding.
Previous: Forming

Even experienced carpenters will find this challenging. The projects “high” difficulty rating was awarded for the complexity of the curved inner form.

Next: Demolding

If you are careful when removing the form to avoid chipping, denting, or scratching it, you should be able to cast many times with this single form.