It is a preparation of slaked lime (calcium hydroxide), water and copper sulphate, used as a pesticide (fungicide and bactericide). It is so called because it was invented in Bordeaux, France.
Prepared fungicide copper sulfate (10 grams) and cal (10 grams) with a liter of water who invented the winemakers of Bordeaux at the end of the 19th century. Currently used in organic farming as a bactericide and fungicide with certain limitations. The homemade recipes to treat mildew and other diseases of the vine and other plants should be very careful and well-informed.