Caring for stainless steel kitchen tools

Stainless means stain-less, not stain-proof

Stainless steels resist corrosion because the chromium in the alloy reacts with oxygen and forms a thin, transparent oxide film on the surface. That film is the protection. It is also self-repairing, but only where oxygen can reach the metal, which is why trouble concentrates in the places air does not go: the inside of a scissor pivot, the seam where a blade meets a handle, the underside of a tool left flat in a puddle.

Two things attack that film. Chlorides, which arrive as table salt, brine, tomato and citrus acids and dishwasher detergent, and prolonged wetness, which keeps the metal from re-forming the layer. Everything below follows from those two facts. Grade sets the starting point: 304 stainless, used in the stainless steel flour duster, is a high-chromium austenitic alloy chosen for corrosion resistance, while the harder martensitic grades in cutting tools trade some of that resistance for an edge that holds.

Hand wash against dishwasher

Most solid stainless kitchen tools are dishwasher safe, and the manufacturers say so. The Japanese-style poultry shears set in roughly 3 mm 3Cr13 blades is rated for the dishwasher, as is the flour duster, as is the stainless steel bench scraper. Rated for it and best served by it are not the same claim.

A dishwasher cycle is a long soak in hot, alkaline, chloride-bearing water, followed by a drying phase that often leaves crevices wet. For a flat tool with no joints, that is harmless. For anything with a pivot, a spring or a bonded handle, it drives water into the one place the oxide film cannot repair itself. A jointed tool washed by hand takes forty seconds and skips the problem entirely.

The rule that covers both cases: wash promptly, rinse fully, dry immediately. Leaving a tool wet overnight in a rack does more damage than the wash did. Avoid steel wool and chlorine bleach on any of it, since the first scratches through the protective film and the second removes it chemically.

Water spots and dull patches

The white marks on a dried tool are not damage to the steel. They are the minerals that were dissolved in the water, left behind when the droplet evaporated. Hard water leaves more of them. They wipe off with a cloth while the tool is damp, which is the argument for drying by hand rather than in a rack.

Deposits that have built up over months respond to white vinegar: wipe on, leave briefly, rinse and dry. Work along the grain of the finish rather than in circles. What does not help is abrasive powder, which removes the spots and the polished surface together and leaves a rougher finish that holds the next round of deposits more readily.

When stainless rusts anyway

Orange marks on a stainless tool usually have one of three causes, and only the third is a fault in the steel.

• Transferred iron. Storing stainless in contact with a carbon steel blade, a cast iron pan or a rusting drawer runner deposits particles that rust in place and stain the surface underneath.
• Trapped residue. Salt, egg or acidic food left in a pivot or a mesh keeps chloride against the metal for days. Mesh sifters and hinged shears are the usual patients.
• Pitting. Small dark craters, generally the result of long exposure to salt or bleach. This one is permanent, though it is cosmetic until it reaches an edge.

Surface staining from the first two causes cleans off with a paste of baking soda and water and a soft cloth, followed by a thorough dry.

Storing and sharpening

Sharp tools loose in a drawer dull each other and cut hands. Engage the safety lock if the tool has one, use the supplied blade covers if it came with them, and give edged tools a slot, a magnetic strip or a block. A shear stored closed also keeps its pivot aligned, which is why almost everything in the kitchen shears and cutters range ships with a latch, a cover or both.

Sharpening splits by tool. Shears sharpen one blade at a time on the beveled face only, at the angle already ground into the blade, with a fine stone or a rod; the flat inner face is never touched, because it is the reference surface the two blades shear against. Kitchen knives take a steel between sharpenings to realign the edge. Scrapers, sifters and dusters are not edged tools and need no sharpening at all, and putting an edge on a bench scraper only damages the board it is used against.