Sacrificial compared with permanent anti graffiti coatings
The sacrificial coating requires regular applications each time a wall is cleaned of its graffiti. However, it does not noticeably discolour the wall which matters if the coating is applied to say the first 2 metres only. On a low wall like the one in the image below, it really does not matter whether the colour or shine of a wall changes and for many people it would be a matter of price comparison to see whether permanent or sacrificial would be better. What does need to be taken into consideration is how often the graffiti re-appears and how important it is to keep that wall unblemished.