Treating your narrowboat to this service is the best thing it could possibly receive to its painted surface, this is because steel naturally wants to rust caused by the mill scale. Mill scale on new steel is dark in colour unless exposed to the damp then it rusts. When a boat is sand or grit blasted the grit penetrates the steel removing this mill scale, significantly increasing the life of any further paint on the hull or cab.
Sand Grit Blasting is the key to a long lasting, problem free, successfully painted narrowboat. Also very important is the conditions in which the narrowboat is painted! If the boat is likely to get damp at any point during the painting process the damp can get trapped under the layers of paint later causing tiny air bubbles to appear known as micro-blisting in which months down the line can pop up to the surface, this is more noticeable on high gloss mirror finishes and usually new boats. Also if there is a lot of grinding in the painting area then the grind dust will settle on the boat in areas and contaminate the painting environment causing tiny spots of rust to appear. Also it is key that the bare steel is clean and free from rust and any oil or grease usually caused in the initial making of the shell.