Air bubbles. Mixed in with concrete, they create voids on the surface of a sculpture. To reduce the amount of bubbles, I bang my molds 200+ times on the floor or work table. Vibration works the bubbles to the surface. Here's a picture of the surface or the wet concrete with the bubbles coming up through the surface after being whacked on the table.
The current paver project is for my Grandma Dorothy's garden. She wants twice as many plain pavers as patterned pavers. Today, I prepped two plain paver models. They are al ready for the mold to be made.
There are two more concrete figure statues in the works too. Pictures of work in process to come...