The first thing you need to know about graffiti removal is the type of paint used and the type of surface they painted the artwork. There are a few different solvents that removers can use, but you need to know what kind of paint you are dealing with to select a solvent. You can easily buy these solvents at a hardware store, but if the graffiti takes up a large portion of a building, it is best to get a removal company.
Spray paint in itself has so many different compounds with intermolecular bonds that require other solvents. There is the risk of damaging the surface underneath the spray paint, so a test patch is always advised.
If you think about acetone, you would probably also think about nail polish remover, and technically you would not be wrong. Still, the acetone used for graffiti removal is a much stronger chemical and can be a lot more harmful if mismanaged. There are acetone alternatives that can be used that are environmentally friendly and non-hazardous. Acrastrip 600 is excellent for day-old graffiti removal and not dangerous to use yourself. Any residual shadows that remain on the surface can be bleached away with pool bleach, but be careful to do this and use protective gear.
The most common remover used for the removal of graffiti against any surface is Ethyl acetate. However, this is not to be confused with Ethanol. Ethanol is an alcohol-based remover where ethyl acetate contains ethanoic acid. The word acid should give you the indication that this is not something you should use yourself. It is very corrosive and robust and is used to break down the paint components without hassle. It is meant to be fast-acting so avoid this one as best you can because it can cause severe burns when it comes into contact with the skin.
This is a chemical-free technique that removes the graffiti quickly and leaves significant damage on the wall underneath. It can remove old graffiti and deep-set artworks, but it will end up ruining your wall, so keep some fresh paint handy. Sandblasting can also be messy because it breaks down the particles on the wall and will likely leave a big mess once you are finished. A good thing about sandblasting is if there is any damage hiding underneath the wall, you will see it and repair it before it gets worse.
Thinners are generally used to loosen up paint off surfaces and specially designed for lacquer paint removal. It is highly effective at removing even hardened stains. Each lacquer thinner compound varies from brand to brand, but the base ingredients will always be the same. Lacquer thinners consist of acetone, methanol, and toluene, and they can be used on any surface to break down the chemical components of any paint, including spray paint. It is always better to consult with a professional removal company about working with chemicals because they are better equipped to handle this sort of thing. They have protective gear and can assess the best way for you to get the walls free of unwanted art works. They could even give you an estimate of what you would need to fork out to have it all repaired, so stick to use the services of a reputable removal company if you would like to have the graffiti removed without losing the wall.