What to pay attention to graffiti on the wall, the paint will not be easy to fall off

Wall graffiti or wall painting on the outside wall is not the same as the inside wall, the outside wall is generally filled with self-spray paint, this wall painting is not afraid of the sun, painted more delicate, will fade and discoloration, the smell of the body's harmfulness is relatively large, with a gas mask (masks are not useful) with a 3M with a canister of masks is better, self-painting paint used away from open flames. Indoor general use of acrylic, the color sticks firmly and less water dilution fast drying, acrylic direct painting on the line (unless the wall skin is not strong), but acrylic on the wall flatness requirements, can not be in the masonry class rough wall painting. After painting with good acrylics do not need to spray protective paint.