Care & Repair
Leather cracks because it lost water, and oil is only half the answer
A dried-out hide fails at the points where it bends, and understanding what is actually leaving the material explains why some treatments help and others do harm.
What keeps leather flexible
Leather is a network of collagen fibres, and it stays supple because those fibres can slide past one another when the material bends. Two things allow that movement: the fatliquors introduced during production, which coat the fibres and keep them lubricated, and a modest amount of water held within the structure.
Both are gradually lost. Water evaporates, faster in dry heated air and much faster with warmth. Fats and oils migrate, oxidise and are drawn out by contact with water and by cleaning. As they go, the fibres begin to stick to one another instead of sliding.
A dry hide bends by fracturing rather than flexing, so the damage appears exactly where the flexing happens: across the vamp of a shoe where the foot bends, at the elbows of a jacket, along the fold of a bag. Cracks are the visible end of a process that began invisibly some time earlier.
Water is both the cause and the cure, depending on how it arrives
Getting leather wet isn’t in itself a disaster. What harms it is the drying, because water leaving the material carries dissolved fats out with it and, if the drying is fast or hot, sets the fibres in whatever position they happen to be in.
This is why a soaked shoe placed near a radiator is ruined and the same shoe dried slowly at room temperature usually isn’t. Heat drives the process at speed and leaves the leather hard, shrunken and often permanently misshapen. Stuffing with paper or setting on a form and simply waiting is dull advice and it is correct.
Salt is the specific winter problem. Road salt dissolves in the water soaking a shoe and crystallises out as a white tidemark as it dries, and the deposits are both unsightly and drying to the leather. They are removed with a dilute solution of water and vinegar, wiped rather than soaked, followed by conditioning once the leather is dry.
Conditioning replaces what has left
A conditioner is a mixture of oils, waxes and often water designed to be absorbed into the fibre structure and restore lubrication. It is not a coating and it is not polish, which is a surface treatment that adds shine and some protection while contributing almost nothing to flexibility.
It is entirely possible to overdo it. Saturating leather with oil softens it past the point of usefulness, which for footwear means a loss of the structure that holds the shape, and excess oil can also darken the surface permanently and migrate through to stain a lining. Little and rarely beats a lot and often.
Different leathers want different things, and the honest position is that recommendations are more contested than they sound. Heavy oil dressings suit thick, vegetable-tanned work leather. Fine chrome-tanned garment leather generally wants a light cream. Suede and nubuck want neither, since anything oily mats the nap; they want brushing, a dedicated eraser and a protective spray.
Rest and moisture management inside a shoe
Most of the moisture a shoe absorbs comes from the foot, not the weather. A day of wear leaves the lining and the insole damp, and leather that stays damp stretches, harbours the bacteria that produce odour and takes longer to recover its shape.
This is the actual argument for a rest day between wearings, and for cedar shoe trees. The tree does two useful things: it holds the upper in a smooth shape while the leather dries, which prevents the creases from setting into folds, and unfinished wood absorbs moisture from the interior. The cedar smell is incidental.
A plastic tree does the shaping and none of the absorbing, which is better than nothing. What matters more is putting the tree in soon after taking the shoe off, while the leather is still damp and can be persuaded into shape, rather than the following morning when it has already dried creased.
Storing it without ruining it
Leather needs air. Sealed in plastic it cannot lose moisture, and in a warm, humid space mould will grow on the surface within weeks, feeding on the oils and finishes. A cotton dust bag or an open shelf is right; a polythene wrapper is not.
It also needs a moderate humidity, which is a genuine tension with the previous paragraph. Very dry heated air draws moisture out and accelerates cracking, and a leather garment kept for years against a radiator will stiffen. A cool interior cupboard away from direct sunlight is the practical compromise.
Before storing anything for a season, clean it and condition it lightly, then support its shape: coats on a broad hanger, bags stuffed loosely, boots with trees or rolled paper in the shafts so they do not fold. A crease set over six months in storage is as permanent as one set by heat.
Common questions
How often should leather be conditioned?
Far less often than most schedules suggest. For shoes in regular rotation, a few times a year is usually enough, and the real signal is the leather itself: if it looks dry and matte after cleaning and the creases feel stiff, it wants feeding. Conditioning on a calendar rather than on inspection is how leather gets oversaturated.
Can cracked leather be repaired?
Surface crazing in the finish can often be improved considerably by cleaning, conditioning and recolouring. Cracks that go through the fibre structure cannot be reversed, because the collagen has physically broken. A repairer can fill and disguise them, and the flexibility at that point is gone for good.
What about suede in the rain?
Suede tolerates rain better than its reputation suggests, provided it is allowed to dry slowly and then brushed to lift the nap back up. What ruins it is oil, salt and heat drying. A protective spray helps and needs reapplying, since it is a finish sitting on the surface and it wears off.
Nikhil writes about fit, fabric, care & repair, mostly the parts other people skip and is unreasonably interested in the detail nobody else checks.