Caring for Steel

Stainless steel is not stainless because of what it is made of. It is stainless because of a layer perhaps three nanometres thick — chromium oxide, formed the moment the surface meets air, self-repairing when scratched. Almost everything that ruins steel hardware is something that attacks that layer. Care is mostly the practice of leaving it alone.

The routine

After each use, wash in warm water with a pH-neutral soap and a soft cloth. Work into the hinge knuckles, the thread of a screw pin, and the recess around a lock barrel — those are where residue collects. Rinse thoroughly.

Then dry completely. Not mostly. Water left standing in a blind hole or under a ring will eventually leave a mark, and salt in dried sweat concentrates as the water goes.

Between partners, wipe non-porous steel with 70% isopropyl alcohol and let it evaporate rather than wiping it off. Ordinary use with one partner does not need it; changing partners does.

What to keep away from it

Chlorine. Household bleach, chlorinated bathroom sprays, and pool water all pit stainless steel by breaking down the passive layer locally. The damage looks like small dark freckles and does not polish out. It is the most common way good hardware is destroyed.

Steel wool and abrasive pads. They embed carbon steel particles in the surface. Those particles rust, and the rust looks like the stainless itself has failed. It has not — but the marks are yours to keep.

Carbon steel contact in storage. Do not keep restraints in a toolbox drawer alongside untreated tools; the same contamination happens by contact.

Heat and hard cycles. Do not boil assemblies or put them through a dishwasher. Adhesives, lock springs, powder coating, and any leather component all fare badly, and the temperature buys you nothing soap and alcohol have not already achieved.

Marks, and how to remove them

Faint brown or amber discolouration — sometimes called tea staining — is usually surface contamination rather than corrosion of the steel. A non-chlorine stainless cleaner, or a paste of bicarbonate of soda on a soft cloth worked along the grain of the finish, will normally lift it. Fingerprints and water spots come off with isopropyl alcohol and a microfibre cloth.

Locks and moving parts

Keep lock barrels dry and clean. If a barrel becomes stiff, use a dry PTFE lubricant sparingly; avoid oils and general-purpose sprays, which attract lint and eventually gum the mechanism. Never force a key. Test every lock and spare key before you use a piece, not during.

Powder-coated parts

Wash with soap and water only. No solvents, no acetone, no abrasives. If the coating chips down to the substrate, touch it up promptly — powder coating is a barrier, and once the barrier is broken at a point, the corrosion works underneath it and lifts the surrounding film.

Leather, where fitted

Where a piece includes leather liners or straps, treat them as the opposite of the steel. Wipe with a barely damp cloth; never soak, never submerge, never use alcohol, which strips the oils and leaves the leather brittle. Air dry away from radiators and direct sun. Condition occasionally with a pH-balanced leather conditioner. Leather is porous and cannot be reliably disinfected, so it should not be shared between partners.

Before every use

Look at it. Check welds for hairline cracks, rings for deformation, hinges for side play, threads for damage, and spring gates for a clean close. Anything that has changed shape has been overloaded, and hardware that has been overloaded once should be retired rather than watched. Parts are cheaper than incidents.