Stainless steel quality is determined by nickel content:
18/0 = 18% chromium 0% nickel content - 430 Grade
18/8 = 18 % chromium 8% nickel content - 304 Grade
15/1 = 15% chromium 1% nickel content - 201/202 Grade
In general, the greater the nickel content, the higher the stainless steel quality, as nickel allows for a brighter, longer-lasting sheen that is more resistant to rust. 18/8 pans have a shiny finish; 18/0 & 15/1 pans have a duller finish.
The first number, "18," stands for chromium content and is invariable in all stainless steel alloys. Chromium prevents rusting. Carbon steel, which has neither chromium nor nickel, is sometimes used for cookware items (woks, fish poachers, etc.); however, carbon steel can rust. Non-stick coatings may lessen, but not eliminate, the risk of rusting.
The performance of stainless steel cookware is largely determined by how well the pan distributes heat, thereby reducing or eliminating "hot spots" and burning. Since stainless steel itself is a poor conductor of heat, all stainless steel cookware must have an aluminum or copper disc added to the base of the pan (the thicker the disc, the better the heat distribution).
Copper is three times more heat-conductive than aluminum. This means that an aluminum disc must be three times as thick as a copper one to get the same heat distribution. For that reason, pans with an aluminum disc tend to have a thicker base and be heavier than those with copper discs. When judging a pan's quality by its weight, one should compare like to like: copper to copper and aluminum to aluminum.
The standard thickness of aluminium and copper discs for stainless steel cookware and the corresponding heat distribution ratings are as follows:
|ALUMINIUM DISC||PANS HEAT DISPERSION||COPPER DISC||PANS HEAT DISPERSION|
|1.5 MM||POOR||0.5 MM||POOR|
|2 MM||MARGINAL||0.8 MM||MARGINAL|
|3 MM||GOOD||1.0 MM||GOOD|
|4 MM||VERY GOOD||1.5 MM||VERY GOOD|
There are two methods of attaching a disc to the base of a stainless steel pan: brazing, and impact bonding.
This is the only way of applying a copper disc to a pan. A special brazing powder is melted at a high temperature and is then cooled down, binding the disc to the pan. Since a disc can only be brazed on the flat portion of the pan's base, it may stop short of the sidewall, exposing the corners of the pan to the heat source and creating "hot spots." This can cause food to burn in the corners of a stainless steel pan if the heat source is not monitored.
“BRAZED AND CLOSED ALUMINIUM BASE”
Impact (Friction) Bonding is a heat-pressure technology that allows the spreading of an aluminium disc across the outer edge of a pan, protecting the otherwise exposed areas from direct heat and thereby significantly reducing the chance of "hot spots" occurring.
Note: Overheating a pan with a brazed disc for an extended period of time could cause the brazing powder to melt and the disc to separate from the pan.Since impact bonding does not require brazing powder, the possibility of disc separation in such pans is substantially reduced. However, as a safety precaution, a pan should never be allowed to boil dry.
Clad metal stainless steel pans are made of stainless steel and aluminium sandwiched together (aluminium being the core layer). These types of pans conduct heat evenly all around the body, including the sidewalls, making them a natural choice for stockpots and saucepans. While they do not require an extra heat conductor at the base, some pans are designed with an additional tri-ply base to further enhance the Cooking experience.
Some manufacturers market tri-ply stainless steel pans with a carbon steel core instead of aluminium. This adds a great deal of weight to the pan and lends the impression that it is of higher quality. However, carbon steel is a very poor conductor of heat compared to aluminium, making this type of tri-ply cookware inferior in performance to traditional clad metal stainless steel cookware.
Which is better: A stainless steel pan with an aluminium or copper base?
In terms of heat control , copper is more responsive. A copper pan gets hot very quickly and cools off very quickly. In order to properly cook the delicate sauces of their cuisine, French chefs often prefer pans with a copper base (however, with proper attention to temperature control, these can be cooked just as well on pans with an aluminium base).
Aluminium heats up more slowly but retains heat longer after the stove is turned off. This is advantageous for stovetop-to-table serving. How many times have you gone back for "seconds" only to find the food cold? An aluminium-based pan will keep food warm during the meal far better than a copper-based pan.