Posted on: 31 August 2016Share
A painted brick wall may seem like a lost cause, especially if you want to reveal the old brick underneath. Fortunately, there is a way to remove layers of paint and grime from bricks so they look new again. Abrasive cleaning, better known as sandblasting, can give your brick walls a new lease on life. The following tips can help you sandblast properly.
Tip #1: Choose the right method
There are two primary types of sandblasting – wet and dry. For masonry work, dry sandblasting works best because it removes the old paint and grime layer cleanly, without creating a goopy mess. Wet blasting can also erode the mortar more extensively than dry blasting, since moisture is better at working its way into porous mortar joints.
Tip #2: Understand abrasive needs
Brick is usually blasted with sand or quartz. These materials are hard enough to blast through the paint and grime, but not so hard that they erode the surface of the brick. A fine grade of sand or quartz, which means a small grit size, is preferred since it won't pit the brick like larger grades could.
Tip #3: Know the amount of pressure
The amount of pressure used to sandblast brick can really vary depending on the specifics of the brick's condition and the thickness of the paint. Generally, you will want to start at the low end of pressure, such as around 40 PSI (pounds per square inch), and then increase it gradually until you find the sweet spot where the paint peels away from the brick without causing damage to the underlying brick surface. Experiment with distance from the wall before increasing pressure. You may be able to use a lower pressure by blasting close to the wall, for example.
Tip #4: Be prepared for damage
The best way to prepare for damage is to avoid it. Make sure windows are boarded over to avoid breakage. You may also want to cover wood trim or doors, or at least avoid blasting them since the pressure needed to clean brick could splinter wood. Older masonry joints may also take some damage during sandblasting, although newer joints are usually fine. If the mortar is damaged, you may need to repoint them after you are done cleaning the brick.
Sandblasting can be challenging for the novice. If you are worried that you will damage your brick wall, bring in a sandblasting professional to complete the task.