Superficial pinholes of ceramic tiles: roots, causes & remedies

The ceramic production process - after the early stages that from the formation of the tile under the press lead to the applications of the glazing line - usually involves a final application of grit or glaze. Sometimes in huge amount.If you do not meet the proper parameters of the process, this application can lead to several problems able to compromise the ceramic surface, both technically and aesthetically.The formation of pinholes is one of the most frequent. What are the roots of the problem and what can we do to prevent it?