"It's a culture and a culture is always evolving," graffiti artist Phase Two said at the 6th annual graffiti art festival in Drogheda, Co Louth, at the weekend.
Based in New York, where he helped to establish graffiti as part of an emerging culture alongside hip-hop, the 42-year-old said graffiti was not just part of a movement, but also a science that was all about writing.
A crew from London, with help from the Drogheda-based TDA (The Dark Angels), created a strong protest against genetically modified food over the weekend.
It runs under the Bridge of Peace on the main Dublin-Belfast road, and stark images of scientists at either end of the pedestrian walkway under the bridge are joined by giant, coloured abstract letters.
In the middle of it all is a mutant, the work of Solo One, a.k.a. Boyd Hill from Kilburn, London.
"This is a story, and the idea is that food gets out of hand, a whole generation gets out of hand and breeds a race of mutants who destroy the people," he explained.
On the other side of the bridge it is all about letters. "This is a production. The letters are SORN. I liked them," said Tom (17), one of a three-man crew from Cambridge over for the event.
He is a member of PWS (Paint Wasters) while his friends are members of BRF (British Rail Fan Club). The TDA has stayed with graffiti since its conception in Ireland - particularly Drogheda - nearly 20 years ago.
"There are nine of us in TDA Klann and we are the only group in Ireland or the UK to hold an annual event like this," Darren Finnegan explained.