THREE QUALITIES OF STAINLESS STEEL ALLOY
Stainless steel quality is determined by nickel content:
In general, the greater the nickel content, the better the quality, as nickel allows a brighter, more durable rust resistant luster.
18/10 pans have a beautiful shiny finish. 18/0 pans have a duller finish.
The number "18" stands for the chromium content, which is the same for all stainless steel. Chromium prevents rusting. Carbon steel, which has no chromium or nickel, is sometimes used for cookware accessories (woks, fish poachers, etc.). Carbon steel can rust. Adding nonstick coatings will lessen the risk of rusting, but will not eliminate it.
COPPER AND ALUMINUM HEAT CONDUCTING DISCS
Stainless steel is a poor heat conductor. To disperse heat (prevent "hot spots" and burning), an aluminum or copper disc must be added to the bottom of the pan.
The performance of stainless steel cookware is largely determined by how well the pan spreads heat, thereby reducing or eliminating "hot spots." This is directly related to the thickness of the copper or aluminum disc. The thicker the disc, the better the heat distribution.
Note: Aluminum requires three times the thickness of copper to get the same heat distribution. Therefore, aluminum discs are always thicker than copper ones. When determining a pan's quality by weight, compare the same kind of pans: copper to copper and aluminum to aluminum.
There are two methods of attaching a copper or aluminum disc to the bottom of a stainless steel pan. These are brazing and impact bonding.
Brazing, the only way of applying a copper disc, is the most common method. The disc can only be brazed on the flat portion of the pan's base. The disc may stop short of the side wall, exposing the corners of the pan to the heat source and creating "hot spots." Food sometimes burns on the inside corners of a stainless steel pan if the heat source is not monitored.