I often mask when coating with the Scotch "blue" painters tape for delicate surfaces to give me nice clean borders, but sometimes I let the brush strokes fly - depends on the image. If I have not masked when coating, I'll mat to show the brush strokes, but this is uncommon as it requires a much larger mat to accommodate the larger opening and still maintain reasonable window borders. I will cut my opening in the mat to just slightly larger than the negative so that I show the full frame plus a small border around it.