The cleaning agent you will use for graffiti removal depends on the surface material to be cleaned, like wood, vinyl, aluminum, glass or masonry. Read on to learn how to effectively remove graffiti from masonry.
Prepare the Area
Gather the necessary materials. Spread drop cloths or plastic tarps, and use masking tape and plastic sheets to cover surfaces not meant to be cleaned. Have hand-cleaner and safety goggles at the ready, as well as rubber gloves, rags, stiff wire brushes, and scrapers.
Make sure the surface is dry and clean before you begin. Start from the top of the surface and finish at the bottom, catching any running or streaking fluids as you work your way down.
Identify the Graffiti
Pressure-washing is found to be most effective in removing chalk graffiti. Spray paint will usually require some type of solvent, cleaner or abrasive. Baking soda-based products, paint thinner, acetone and WD-40 have been known to work on concrete and brick surfaces.
Sometimes the trial and error method is the best approach. The first attempt should be with the least-invasive method available. This might include using a high-pressure washer (1000 to 3500 PSI) to remove graffiti from unadorned concrete. Carved masonry or architectural brickwork, however, might be vulnerable to pressures above 500 PSI. Use hot water and a wide-angle fan-type nozzle, as opposed to a concentrated jet-type spray, which can damage some surfaces.
Use a Combination
Sometimes it is best to use a solvent in addition to a pressure-washer. Apply the solution to the surface and let it settle in before using the pressure washer.
Work Large Areas
Do not focus on the graffiti itself, as this may permanently etch or 'shadow' the graffiti outline into the surface.
Apply a Preventative Coating
A non-sacrificial, permanent coating is unaffected by the graffiti removal process, while a sacrificial coating would have to be continually replaced. An example of the former is CPU 647 Barrier Coating, a waterborne polyurethane consisting of 2 compounds that are mixed together before use. Once applied, it forms a protective barrier and prevents additional coatings or markings from adhering to the surface; without a solid bond, they are easier to dissolve.
If all else fails, you can re-paint, but you will have to re-paint the entire surface. You may have to apply multiple coats to prevent the image from bleeding through.
Before attacking graffiti yourself, consult a graffiti-removal contractor or specialist. Local governments and municipalities will remove graffiti from public buildings, but it is the responsibility of the owner to maintain private property. There are often volunteer groups within the community that will assist homeowners with graffiti removal.