Surface Abrasion of Stainless Steel

Question:

In our plant, we produce industrial equipment cabinets. One of our customers ordered stainless steel cabinets, which must be painted. I am having a problem abrading the stainless steel surfaces as a pretreatment prior to painting. I read a reply of yours to a question regarding coating of stainless steel. Do you have any recommendations as to what surface roughness needs to be obtained on coating stainless with an epoxy coating? Some say sanding the surface, while others indicate a surface etching of about 30 microns or more. My experience, without measuring, is that wire brushing or using a mechanical wire (stainless steel) brush only seems to polish the surface and doesn't give any discernable tooth. Do you have any ideas? L. B.

Answer:

As far as a surface profile for abrasive pretreatment of stainless steel, I don't have any recommendations. If you can see the roughness, it should be sufficient. If it is too rough, it might telegraph through the paint film. Just like the old childhood game, "...scissors cut paper, rocks break scissors...", you must abrade the substrate with something harder than stainless steel. With this in mind, pretreatments using hand sanding, abrasive blasting equipment, abrasive wheels, abrasive belts and discs may be better choices. Suppliers of this equipment are listed on pages 245 to 248 of the Products Finishing 2005 Directory and Technology Guide.