Table of Contents
Quick answer
Hygroscopic substances absorb airborne moisture. Salt clumps in humidity and can weep on lamps; anti-caking agents help table salt flow.
The property of absorbing moisture from the surrounding air. Salt is highly hygroscopic, which is why it clumps in humid conditions and why salt lamps can weep water. Anti-caking agents in table salt counteract this property.
Hygroscopic materials absorb moisture from the air. Salt is strongly hygroscopic, so it clumps in humid kitchens and weeps on lamp surfaces. Anti-caking agents in table salt reduce but do not eliminate this behavior.
In Practice
A salt cellar cakes shut in summer humidity. Himalayan salt lamps form wet patches when indoor relative humidity stays high for days.
Hygroscopic FAQ
Humidity triggers hygroscopic bonding between grains. Anti-caking agents in some table salts slow clumping.