fat lime

fat lime

A mason mixes fat lime with sand to make mortar.

Definition
  1. Noun:
    • Highly pure lime: "fat lime" refers to a type of lime (calcium oxide) that contains a high proportion of calcium and little to no impurities, such as clay or sand. It is produced by burning pure limestone and is known for its smooth, rich, and "fatty" texture when slaked (mixed with water).
    • Slaked lime for construction: In practical usage, "fat lime" is often used to describe lime that has been slaked (hydrated) and is suitable for making mortar or plaster due to its high plasticity and workability.
Usage Examples
  • Noun:
    • The builders preferred fat lime for plastering because it gave a smooth, even finish. (A high-purity lime used in construction.)
    • Fat lime is mixed with sand to create a flexible mortar that does not crack easily. (Slaked lime with high calcium content.)
Advanced Usage

  • "Fat lime" vs. "lean lime": In masonry, "fat lime" is contrasted with "lean lime," which contains more impurities and is less workable. Fat lime is more expensive but yields better results for fine finishing.

    • For the cathedral's intricate carvings, the masons used only fat lime, as it could be moulded into delicate shapes. (High-purity lime for detailed work.)

  • Chemical context: Chemically, "fat lime" is nearly pure calcium oxide (CaO), which, when slaked, produces calcium hydroxide (Ca(OH)₂) with a high yield.

    • The laboratory required fat lime for the chemical reaction to ensure no interference from impurities. (Pure calcium oxide.)
Variants and Related Words

  • Lime (n): a general term for calcium-containing materials, including quicklime, slaked lime, and agricultural lime.

    • Lime is used to adjust soil pH in farming. (General term.)

  • Quicklime (n): unslaked lime (calcium oxide), which is the raw form before water is added.

    • Quicklime reacts violently with water to produce heat. (Unslaked lime.)

  • Slaked lime (n): hydrated lime (calcium hydroxide), produced by adding water to quicklime.

    • Slaked lime is the form used in most construction applications. (Hydrated lime.)
Synonyms
  • Pure lime: lime with minimal impurities.
  • High-calcium lime: a technical term for lime with over 90% calcium content.
Idioms
  • "To be fat with lime": an old expression meaning to be rich in lime content, especially in reference to soil or mortar.
    • The soil here is fat with lime, making it ideal for certain crops. (Rich in lime.)
Related Terms
  • Lime mortar: a mixture of lime, sand, and water used in building.
    • Fat lime creates a lime mortar that is more flexible and breathable than cement mortar. (Specific application.)