Rough Textured Paint Finishes

Q. Will you please tell me how to get a slightly rough, sand like finish (which is more rough than normal matt finish) painted surface on an aluminum surface. I have seen many commercial equipments like medical equipments, x-ray machines, control boxes having such finishes. I am interested in using polyurethane paint , shade RAL 7001.

A. You are probably referring to powder coatings that are specially formulated to provide these textured finishes. Some liquid-applied coatings also have textured finishes, but they are formulated for this purpose. The following is a link to one of many companies that provide textured powder coatings; http://www2.sherwin-williams.com/chemicalcoatings/systemGuideMetalAdv.asp?clr=true

If you do not have access to such coatings, you can achieve some texture by applying a wet coating with less atomizing air than usual. First apply a smooth base coat of the coating. Allow it to flash dry for a few minutes and then apply a second coat so that the paint is under atomized. You will need to experiment with the air pressure until you get a desirable finish. Please be aware that when you apply such a textured, under atomized coating you cannot rely on this topcoat to provide corrosion protection to the aluminum. It is there solely for decoration.

Best wishes,

Ron Joseph