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Evaporation

Evaporation

Related Materials

WaterSaltSugarClayWoodCharcoal

Brief description

Evaporation is the phase change where liquid water becomes vapor, removing moisture from surfaces and solutions. It is a core process behind Salt & Preservation because it concentrates brine and dries food to slow spoilage.

Use / Function

  • Brine concentration: Turns seawater or brine into crystallized salt.
  • Sugar concentration: Reduces plant juice to crystallize Sugar.
  • Food drying: Lowers water activity to preserve meat, fish, and plants.
  • Surface cooling: Provides passive cooling when water evaporates.
  • Moisture control: Reduces dampness in storage and materials.

Operating principle

  • Energy absorption: Water molecules take heat to escape into the air.
  • Airflow and humidity: Dry, moving air speeds evaporation; humid air slows it.
  • Surface area: Thin layers and wide pans evaporate faster.
  • Salinity effect: Salt lowers vapor pressure, so brine evaporates slightly slower than fresh water.

How to create it

  1. Expose a thin layer: Spread brine or food on shallow trays or racks.
  2. Promote airflow: Place in breezy shade or use Controlled Fire for gentle warmth.
  3. Protect from contamination: Cover with cloth or mesh to keep insects and dust out.
  4. Monitor dryness: Check texture and weight; stop when the surface is dry and stable.
  5. Finish and store: Move to clean Containers and keep sealed.

Materials needed

  • Essential: Water, Salt or food to dry, shallow Containers.
  • Tools: Drying racks, cloth/mesh covers, low heat source (sun or Charcoal).
  • Possible substitutes: Porous Clay pots for slow evaporation; wind exposure instead of heat.

Variants and improvements

  • Solar pans: Wide shallow ponds for large-scale salt making.
  • Shade drying: Reduces oxidation and insect pressure for herbs and fish.
  • Low-smoke drying: Use Charcoal for steady heat.
  • Evaporative cooling: Wet cloth or porous pots to cool storage.

Limits and risks

  • High humidity: Greatly slows evaporation.
  • Contamination: Dust, insects, or animals can spoil food.
  • Overheating: Too much heat can cook or harden food surfaces.
  • Uneven drying: Thick pieces trap moisture and can rot inside.
  • Water: The liquid phase that evaporates.
  • Salt: Concentrated by evaporation for preservation.
  • Sugar: Concentrated from plant juices before crystallization.
  • Clay: Porous containers aid slow evaporation.
  • Wood: Racks and structures for drying.
  • Charcoal: Low-smoke heat for controlled drying.