Cutting edge.

David Mellor's 'City' series is the last word in cutlery design, the product of a most sophisticated understanding of technical process and human feelings.

David Melior is the best known cutlery designer in the UK. He has also enjoyed a distinguished career in industrial design more generally. Born in Sheffield - the cutlery city par excellence - he trained in silversmithing at the Sheffield College of Art before moving on to London's RCA. His talents were confirmed by scholarships and design awards, and he received commissions of national importance, but he chose to return and remain in his home city, involving himself increasingly in the manufacture of his own designs. In 1990 he moved his factory into the famous Round Building at Hathersage by Michael Hopkins, and he did not just act as client but participated in its design. Although Hathersage is 10 miles from Sheffield, it lies close enough to allow continuing exchange with the network of specialists and toolmakers on which he has always relied, so Mellor remains essentially a Sheffield man and the progressive figurehead of cutlery expertise. Unlike many fashionable designers he does not bestow forms on a purely visual basis, but with a deep understanding of how they are used and produced.

His latest project for top of the range cutlery is a rethink of old problems leading to a radical and technically difficult solution. The problem of the knife is the difference between blade and handle. The blade needs to be flat but of the hardest steel, which needs annealing after it is formed to produce a hard cutting edge, but the job of the handle is to fit the hand, so it is ideally rounder and softer. The traditional solution is to use contrasting materials such as steel and bone or plastics with some kind of joint, but this is always the weak point, and subject to increased stress in the dishwasher age. The advent of stainless steel allowed durable and familiar one-piece designs including Mellor's own 'Thrift' of 1965 and 'Classic' of 1984, but the limitation was that the handle must be relatively flat. For even if the manufacturing difficulties of thin blade with fat handle are overcome, balance is upset by the weight of excessive metal in the handle.

With 'City', Melior sought to combine the elegant continuity and efficiency of a single piece instrument with the generosity of a rounded handle. To solve the weight problem he decided to make the latter out of two shells which, welded together, could in turn be welded to the blade, a forging already hardened and ground. A fourth piece of metal was added inside the handle as a weight to achieve the desired balance. So it achieves the required shape and weight while allowing different alloys to be used for the various parts - harder for the knife blade, more corrosion resistant for the handle.

A further innovation is the ability to adjust the balance without changing the shape. The disadvantage is the complex manufacturing process, for not only is the perfect welding of the seams fiendishly difficult: the knife blades must also be hardened and tempered for a second time after assembly to remove stresses and prevent corrosion. Mellor has been developing the process over a couple of years, exploring the tools available and doggedly finding his way through each problem. The resulting pieces look simple and elegant and are a joy to handle. Circular at the stem, they rotate easily between the finger tips, while the semicircular end of the handle nestles comfortably in the hollow between thumb and forefinger. Like all the best art they seem effortless and reveal none of the background struggle. The difficult joints and hollow handle are quite imperceptible.