Many times people have a desire, for one reason or another, for plastering over bricks. Perhaps an interior brick wall no longer holds the appeal it once did, or you have decided on a new look for the tired appearance of a dated fireplace. Whatever the reason, knowing how to apply plaster over a brick surface can save you money by being able to do it yourself rather than paying a professional.
The most important criterion for successful plastering over bricks dictates that the surface provides enough porosity for suction to occur. Plaster must have a good, rough surface in order for it to properly adhere to it. A material such as glazed or semi-glazed ceramic tile, for instance, does not provide enough roughness/porosity and would need to be taken off before attempting to apply plaster.
Plaster will also not adhere properly to smooth surfaces such as glass, Plexiglas, or plastic. Unless bricks have been unusually encased with some type of thick, slick sealant (plastic, polyurethane, multiple coats of paint, etc.), no problem should exist in getting plaster to adhere. Plaster also adheres well to cement block, sometimes called cinder block.
Number of Coats, Drying Time, and Temperatures
Plaster, known for its beauty and durability, does have some characteristics with regard to its application that must be taken into account, one of which is the number of coats necessary for proper application. For some surfaces, such as drywall and sheetrock, three coats of plaster are necessary, each coat drying thoroughly before the next can be applied. For plastering over bricks, however, only two coats of plaster are needed.
Mix the plaster according to the manufacturers directions. For ease of application and for the best results, add water until the mix reaches a thickness that approximates that of cake frosting. Apply the first coat of plaster fairly thinly using a trowel.
Allow it to dry at least four hours, preferably overnight. Do not attempt plastering over bricks when temperatures fall below 55 degrees Fahrenheit (13 degrees Celsius) or in very humid weather. This causes the plaster to take too long to set. Conversely, avoid applying it in conditions of dry heat that can cause plaster to dry out too quickly and crack.
Smooth or Textured?
A number of finishes can be achieved when plastering over bricks, depending on the desired result. Your second coat determines the final look, so now is the time to decide whether you want a smooth or textured appearance for your plaster project. While a trowel is most often used for a smooth surface, any number of tools can be used to create a textured appearance: a float, sponge, crumpled paper, or other objects you may dream up to use to create a unique texture.
After allowing the second coat of plaster to thoroughly dry when plastering over bricks, you can now finish it with a primer base and your favorite color of interior paint or a wash. You now have a brand new look that is destined to become a classic!