1. Not all materials respond the same to paint. The more porous the material, the more likely the paint with get deep into it and be more difficult to remove. Sometimes the brick will clean up completely, but the mortar may hold on to a little of the color. On older brick (50 years plus) you tend to get spots where the finish on the brick is already worn away by the elements. In these situations, the paint from the graffiti may stick more to those areas without finish.
2. Not all paints react the same to brick or masonry. Some paints, especially acrylic/latex, do not penetrate the surface of the brick but rather cling to the surface. This is typically much easier to remove than oil based paints that tend to penetrate much deeper.
3. Do-It-Yourself solutions can cause damage. Using gasoline, kerosene, or other “household solvents,” may remove the graffiti, but may also permanently stain the brick. These solvents are not recommended for graffiti removal.
4. Time and weather are factors as well. As with most types of cleaning, the sooner it can be removed the better. Graffiti that has been allowed to sit through several seasons tends to be more difficult to remove. As you might guess, the sun tends to “bake” the paint causing it to stick more. Additionally, if the graffiti has been left to sit for several years, once it is removed, it can sometimes have a “shadow” where the color of the brick around the paint has faded.
5. Use caution around doors and windows. One of the added benefits of soda blasting is that the baking soda will not etch glass. We have actually used it directly on glass without scratching it. However, if you use more aggressive blast media, you can easily cause damage. Also, given the nature of baking soda, plastic containment on the inside of windows is a must to keep dust from getting throughout the building.
6. While the benefits of soda blasting are many, one tool may not be enough for every job. There are times when chemical cleaning along baking soda, or even the use of other abrasives may be effective. Blastmaster can help you determine what will best suit your situation.