Tool care: cleaning, oiling, preventing rust, checking handles

Rust forms when iron reacts with water and oxygen. This creates a reddish-brown, flaky layer that does not protect the metal but keeps growing deeper into it. Salt – for example from sea air or sweat – and acids from food or plant sap speed this process up considerably. That is why a knife used to cut fruit and then left unwashed often rusts overnight.

A thin film of oil breaks the contact between water and metal. It does not need a thick layer – a few drops on a cloth are enough for a whole blade. Too much oil tends to attract dust and dirt. For knives that touch food, use a food-safe oil.

Wood behaves differently from metal: it takes up moisture from the air and releases it again, swelling and shrinking as it does. If an axe handle dries out a lot, for example in a warm room, it becomes slightly thinner and the head can loosen. Leather holds moisture for a long time and contains tanning agents that can attack steel – one reason not to store blades permanently in leather sheaths.

The most important step is drying at once. A tool that goes wet into a sheath, bag or box keeps rusting there out of sight. Also think of hidden places such as the joint of a folding saw or the gap between blade and handle. Resin and plant sap often come off better with a little oil than with water.

Light surface rust – a thin orange haze – can be removed with oil and a fine abrasive pad or a blade eraser. Then oil again. Deep rust pits, on the other hand, are small holes in the steel and permanently weaken the edge. Carbon steel often develops an even, dark grey colouring over time, called a patina. It is something different from red rust and no cause for concern.

Each time you care for the tool, also check the handle: cracks, splinters, a wobbling head? You can occasionally treat dry wooden handles with linseed oil. Let leather sheaths dry in the air, not by the fire, and treat them now and then with leather care. Stainless steel needs less attention but is not rust-proof – it is also dried and oiled occasionally.

Linseed oil and other drying oils harden by reacting with oxygen from the air. This produces heat. In a crumpled rag that heat can build up until the cloth catches fire by itself – a known cause of workshop fires. So let rags dry laid out flat outdoors, or dispose of them in water in a closed metal container.

When cleaning and oiling, your hand is close to the edge. Always wipe from the spine towards the edge, or lay the cloth over the spine and pull it outwards – never run your fingers along the edge. Work seated on a firm surface and do not let yourself be distracted.

A loose hatchet head or a cracked handle is not a cosmetic flaw but a hazard: the head can fly off when you strike. Soaking the head in water so the wood swells helps only briefly and damages the handle in the long run. Such a tool is repaired properly or replaced. Everything is stored dry, with a blade guard and out of children's reach.

Make care a fixed routine, like brushing your teeth: after every use, before the tool is put away. A small bag with a cotton cloth and a small bottle of oil belongs in your kit for this. After rain or use at the coast, a second look the next day is worthwhile.

Before longer storage, for example over winter, everything is cleaned, dried and oiled especially thoroughly. Blades go into a dry blade guard, not into damp leather sheaths. Have a quick look at the tools every few weeks. And read the manufacturer's information – it takes precedence over this general guide.

The US Forest Service axe manual treats care, storage and handle inspection as an integral part of safe work. Books on sharpening also stress that a clean, rust-free edge is the precondition for good sharpening. So care and sharpening go together.

Blades do not belong in the dishwasher: heat, moisture and harsh detergents are hard on steel, wooden handles and glued joints. Chainsaws and power tools have their own maintenance instructions and are not the subject of this entry. For hand tools: a few minutes of care add many years to the life of a good knife or hatchet.