Stainless steel linings come in three finishes.
In the photo above, left to right, the finishes are brushed, mirror, and matte.
A brushed finish has been ground with an abrasive to create a uniform pattern of tiny lines. It’s a very common look for stainless steel. Your refrigerator, microwave, and other appliances in stainless steel finish are very likely brushed in short parallel lines, but the stainless interior of a pot is brushed in a circular pattern so that the base of the pan has rings kind of like a vinyl record. The abrasive can be sandpaper or a carbide-steel head, like a record player needle, that etches the lines onto the surface.
Here’s the brushed finish on the interior of a bimetal pan. Notice how the concentric rings catch and reflect light to create the so-called “sunburst” pattern. This is the quickest way to recognize a steel lining from afar: look for refracted light patterns creating distinct lines radiating from the center of the pan.
A mirror finish has been buffed to a shine by sanding or buffing the interior with successively finer grades of abrasive. The repeated steps involved and the risk of inadvertently marring the finish make this a more time-intensive and therefore expensive process than the other two.
Here’s what a mirror finish looks like.
A matte finish is a uniform surface that looks almost like metallic gray paint. (Teflon and other non-stick applied surfaces look similar.) This surface is produced from bead-blasting or sandblasting: an industrial nozzle sprays a high-pressure stream of sand or metal beads against the stainless steel to create a smooth featureless surface.
This is what a matte finish looks like. Please don’t confuse the light surface scratches with a finish — this is the underside of a lid that has light marks from sliding. The finish is the uniform metallic gray that looks almost like paint.
Who uses what?
Round pots and pans tend to have brushed finish interiors. Because these pans are symmetrical, they can be spun against an abrasive surface or have a round grinding tool inserted into the pan cavity. (The exception is Falk, which uses a matte finish on all its pots and pans.)
Asymmetrical pans, like oval gratins and roasting pans, tend to have matte finish interiors. These pan shapes can’t be spun against an abrasive surface. As mentioned above, Falk Culinair uses a matte finish inside all its pots and pans.
The only copper pan manufacturer that applies a mirror finish to its interiors is Bourgeat, and only then to certain product lines at certain times. Look carefully at a Bourgeat pan before you buy it so you know which type of lining it has.