It is a myth that some metals will not be scratched! Any metal can be scratched and dented. The specifier should therefore avoid decorated metals, plain or laminates, for any horizontal application. Wear and vandalism are a fact of life; many modern textures and small incremental design patterns will effectively hide ordinary wear and light intentional scratching. Some textures such as Random Swirl type grinding finishes were actually designed to absorb heavy wear and vandalism. Other finishes such as long grain Satin, Polishing, Structure, Non Directional Satin, can actually be reconditioned and repaired in site, if a repair intervention can be justified economically. In many countries, metal maintenance teams are trained to recondition such surfaces. If the metal is severely dented, it cannot be repaired and must be replaced.
Scratch Resistance Testing
Below are test results showing the relative scratch resistance of various GageMetal finishes. The testing method used was ASTM D3363-00 Pencil Hardness. We tested the applied color finishes and topcoats used on GageMetal against certain benchmark finishes including standard stainless steel finishes, exterior automotive and appliance finishes.
Although our applied finishes demonstrate very good scratch resistance, please remember that nothing is “bullet proof”, and literally all finishes can be scratched. If the scratch is deep enough to go through the applied finish, then the underlying substrate will be revealed.
|Mill Finish, 304 SS||X|
|#4 Satin, 304 SS||X|
|GageMetal Transparent Color||X|
|GageMetal Opaque Color||X|
|Exterior Automotive Finish||X||X||X|
|#8 Polished, 304 SS||X|
Pencil hardness (ASTM D3363-00) is a standard method to test scratch resistance. Pencil lead comes in varying degrees of hardness. A soft lead leaves a heavy dark line while a hard lead leaves a finer gray line. The standard hardness of pencils goes (hardest to softest) 6H, 5H, 4H, 3H, 2H, H, F, HB, 2B, 3B, 4B, 5B, 6B. When the pencil lead is drawn across the surface of a finish a soft lead may not scratch the finish while a hard lead may. Finishes can then be rated by the hardness of the pencil lead that will scratch the surface.
As a reference, #8 polished, 304 stainless steel is rated an F, exterior automotive finishes rate between F to 2H and electroplated gold on stainless steel scratches with a 4B lead.
By contrast, applied Gage opaque or transparent colors on stainless steel or aluminum achieve a 6H rating. The topcoat used on aluminum GageMetal also rates a 6H.
Refer to chart above.