boildown vs puddling

boildown

noun
  • The process of boiling something down; concentration by means of evaporation. 

puddling

noun
  • The action of forming a puddle. 

  • The act of lining a canal with puddle to make it watertight. 

  • The first true industrial process to produce steel from pig iron. 

  • A group of mallards (ducks). 

  • A behaviour in which animals like butterflies seek out moist substances to obtain nutrients. 

  • The process of working clay, loam, pulverized ore, etc., with water, to render it compact, or impervious to liquids. 

How often have the words boildown and puddling occurred in a corpus of books? (source: Google Ngram Viewer )