For a non-porous surface like concrete, what is the best choice for the first coat of plaster?

For a non-porous surface like concrete, the best choice for the first coat of plaster is bond. This refers to a bonding agent specifically designed to adhere plaster to surfaces that do not readily absorb moisture, such as concrete.

Concrete is dense and smooth, which means that traditional plaster might not form a strong bond without a suitable primer. The bond coat provides the necessary surface texture and adhesion, allowing subsequent layers of plaster to adhere effectively. It essentially serves as an intermediary layer that enhances the grip of the plaster to the concrete, ensuring longevity and strength in the plaster application.

Using other materials like wood fiber or neat mix as the first coat would not provide the same level of adhesion and would likely lead to peeling or cracking over time. Wood fiber, for example, is more suitable for different applications and substrates, while a neat mix, often used for finishing, may not perform well in promoting adhesion on slick surfaces like concrete. As a result, starting with a bond coat is crucial for achieving a successful plaster system on non-porous surfaces.