Fineline Product Usage & Roofing Overview 3
With a breathing paint System, the performance is quite different, as moisture and essential oxygen is able to enter and react with the metallic coating, and then evaporate as the system dries out. Therefore it is not an inherant requirement to seal off cut edges and drilled or punched holes, to keep moisture out, as moisture in the coating system is beneficial to the overall performance, so long as it is able to dry out, so that a protective oxide layer is able to form.
Having now established that the pre-paint systems used in NZ. are able to absorb and release moisture in tune with the environmental conditions, we can address the issue of scratches to the paint surface.
While it is generally agreed that the primer has anti corrosive properties, and the Top Coat, of the paint system also provides some protection from enviromental influence, the cladding has by it's metallic coating, significant cathodic protection.
In some circumstances, as with with zinc rich alloys, an ability to heal cut edges is possible, but less so with Aluminium rich alloys that are more common in NZ. although both are available.
With these things in mind, it becomes obvious that light fretting and scratches on the painted surface of pre-painted steel, do not represent a threat to the life cycle durability of the product, and therefore should not affect an issue of Warranty.
What we are confronted with in our industry is the aesthetic appeal, or the eyesore effect.
When a pre-painted product is scratched by a sharp object, it remains scratched, and it is best to leave it alone from a performance perspective.
When the scratch is (Touched-up), it is still a scratch, but is now less obvious, if done expertly with minimal application technique. The eyesore is temporarily removed, and maybe the minor damage will go unnoticed for some years. It is very possible that there may be a colour difference that becomes more evident over time, since different paint systems, react individually to UV light, as can variable paint thickness, so the repaired scratch may show up more down track than the original scratch.
It is my opinion that leaving a scratch or carefully disguising a scatch will not affect the durability of pre-painted metal products at all.
The issue is that warranties are not just about durability of the substrate, but also involve colour performance. Historically many warranty claims have been disallowed due to excessive use of (spray bombs) over large areas that subsequently have had poor colour retention, resulting in patchy paint on cladding products.
Author: Philip J. Meyers
27-11-2023