FOUR: CASTING

• Your casting table should be indoors so your countertop can cure away from direct sunlight.
• Turn vibrator on to a relatively high speed to help the recycled glass terrazzo mix flow.
• Using a bucket, transfer the terrazzo concrete mixture from tub to form, bucket by bucket, until all the mix is in the form.
• Spread the mix and push it into the corners with gloved hands or a trowel.
• The form should be filled completely and evenly.

Step 2 – Vibrate and Trowel

• If you’ve over filled the form, screed the excess concrete off the casting with a clean, straight edge of wood or steel. Work the board diagonally across the surface of the concrete in a sawing motion being careful not to disturb the foam walls or wall liners.
• Once the terrazzo mixture is level with the top of the form and no more concrete is required to fill the form, turn the vibrator to a low setting.

Step 3 – Compact Mix

• Allow the vibrators to run for roughly 8 minutes while all trapped air is driven from the terrazzo mixture. This will help reduce the number of air bubbles in the recycled glass countertop section.
• Tamp around the edges with a trowel to help compress the glass into unfilled corners and drive any air that might be trapped along the edges of the form.

Step 4 – Cover and Cure

• Tent the form with a thin covering of plastic to create a humid environment. Do not cure in the sun.
• For this project we allowed the countertop section to cure for approximately 24 hours. Our shop temperatures dropped to 68ºF over night and the highs were around 75ºF.
• Once the countertop section is fully cured, take some time to grind off any high spots or rough areas. This will save time during installation.