Does a Dishwasher Ruin the Temper of a Knife?

Many people ask whether putting a knife in a dishwasher ruins the temper of the steel.

It does not.

Dishwashers typically operate at around 50–70°C, whereas knife steels are tempered at temperatures commonly around 250°C or higher, depending on the steel. Dishwasher heat cannot alter the blade’s heat treatment or soften the steel. Uddeholm’s ELMAX steel guidance specifies a preferred tempering temperature of 250°C or higher.

However, we absolutely do not recommend putting good knives in a dishwasher. Dishwasher detergents contain aggressive alkalis and salts that can attack the blade’s surface. Chlorides are particularly corrosive—even stainless steel can stain, pit or rust after repeated exposure. The hot, humid environment after the cycle makes matters worse, especially when knives remain damp for hours.

Once rust penetrates through the surface and into the blade we may never be able to fully remove the pitting and craters that it creates as complete removal could compromise the integrity of the blade.

A knife may also knock against cutlery or dishwasher racks, damaging its fine cutting edge. Wooden handles can swell, dry, split and loosen as repeated washing strips away their natural oils.

Always place a knife under a running tap and hand dry with a towel after use.