If we want to talk about Street Art and the origins of Graffiti then we need to turn back the clock for about 5 centuries and place ourselves in Italy during the Renaissance age. Like all other beautiful things, also Graffiti came from Italy.
The 16th century was the age when “Sgraffito” (Italian “graffiare”: “to scratch”), was born: a very specific mural technique of painting on building facades of by working with different layers of plaster on moisturized surfaces and adding the colour finish on them. The colour pattern however is not the final layer. The layering of plaster and colour consists of putting down a preliminary surface, covering it with another, and then scratching the superficial layer in such a way that the pattern or shape that emerges is of the lower colour.
This type of art production war naturally very cost intensive and thus the buildings displaying Sgraffito were properties of high values owned by wealthy people. The motifs of Sgraffito were accordingly: they were either celebrating a great history of the family living within the walls or they were actually the first form of advertising on different guild buildings by telling which goods / products are being produced inside.
This relationship of the Sgraffito to the life within the house and displaying it on the exterior skin had obviously many turns throughout the history and in the 20th century it was even the opposite. But one thing remained the same: Sgraffito is telling the inside life of a building on its exterior. It became a tattoo, revealing the hidden stories. Sgraffito was glorifying them; Graffiti is being far bolder.
However, if you compare the 500 years old technique of Sgraffito with the contemporary Graffiti you will find that it is exactly this particular metaphysical layer, which makes both so interesting and extremely related to each other: on the technical level Sgraffito is scratching the surface to reveal what´s underneath and Graffiti has turned exactly this technique into its central position.