How is the copper and stainless steel in Falk Copper Cookware bonded together?
Posted by Carol Corke, Last modified by Neil Corke on 18 November 2013 07:21 PM
When a young industrial engineer named Paul Van Achter perfected the technique of bonding stainless steel to copper in 1983 he was unaware that it was about to revolutionise the way copper cookware had been manufactured for more than 200 years.
Up until then, copper cookware was typically lined with a thin layer of tin, which while providing the necessary separation between the food being cooked and thermally conductive copper was by no means an ideal solution. : Tin has a melting point of only 232 degrees Celsius making it unsuitable for cooking at high temperatures, and requires periodic, and expensive, relining.
Stainless steel on the other hand is practically indestructible, and is totally hygienic, but does not possess the same conductive properties of copper.  :The interior lining therefore had to be very thin (0.2mm) so as not to diminish the superior heat distribution and control, which had made copper cookware so highly regarded by chefs around the world.
Copper is a soft, or ductile, metal, which makes it is easy to shape with hand tools when heated.  :Stainless steel is much less ductile requiring specialist machinery to press and shape.
The major challenge faced by Paul when attempting to laminate a thin layer of stainless steel and a thick layer of copper plate was creating a permanent bond between the two very different metals, that would not separate when these were pressed to form the vessels of pots and pans.
The bond between the metals is created by pressing these together under very high pressure (850 tonnes/cm²) resulting in a metallic “intercristalline” connection.
Three years of trial and error finally resulted in the discovery of heat resistors, which when added to the lamination process, allowed the bimetal to be heated to a temperature high enough to obtain the required ductility for pressing.
The final result soon became the “gold standard” of cookware and was quickly adopted by the other manufacturers of high quality copper cookware who now use this same bimetal for their premium product lines.