Most liquid coatings have a tendency to flow away from the edges and cause a reduction in the thickness of the dry paint film. The paint flows away due to the surface tension of the paint film and the shrinking of the film as it cures. This causes the paint film at the edges to become thinner than other parts of the component and exposes the areas to early attacks by corrosion
Factors considered when stripe coating are the configuration and nature of the surface of the structure, and the type of the paint system. A brush or roller is used to apply the coating, depending on the job size and accessibility. Additionally, a different color is used to differentiate the coating from the main coating
Proper application of the stripe coating is required to ensure that the coating does not introduce defects in the paint film that may lead to rusting and other related problems
Stripe coating is more effective when the edges are rounded and this is achieved by grinding the sharp edges. In addition, the stripe coating should extend for at least 2 cm or one inch from the edge and be allowed to set to touch before applying the full coat. However, the drying time should be not be too long, otherwise rusting of the unprimed steel surface may occur if left open for long
The coating serves several purposes, with the main ones being
- Filling in the small voids and irregularities such as the porosity in welds
- The brush helps wet the surface and allows paint to flow over weld beads, cracks, crevices, etc
- Providing adequate coverage and added protection on tight corners, welded areas, and flamer-cut edges; behind rivets, bolts threads, and other vulnerable, irregular, and difficult-to-access areas
