This unit of measure (also specific density) describes the quotient of two densities as a dimensionless size ratio. In viticulture, the weight ratio between the volume of wine or wine grape to the same volume mass of water (with density 1.000) at a measuring temperature of 20 ° Celsius. For grape must, this is also called Mostgewicht designated. The result is represented by four decimal places with the code "d" (for density) or "d20 / 20" (20/20 refers to gauge calibration and measurement temperature). The value is analyzed in the wine in quality wine tests and is for the award of the Official test number (Germany) and State test number (Austria) compulsory.
Thus, the status of a wine is clearly identified, because a change (manipulation) should take place after the test, this could be clearly determined by further analysis. The deviation may amount to a maximum of 10 ten thousandths. At a value of 0.9917, the bandwidth 0.9907 to 0.9927 is considered identical - already 0.9906 would be considered a change. In addition, the relative density is an indication of the total extract and the alcohol content a wine. The measurement is carried out by means of pyknometer or according to the bending oscillator principle, with lower requirements a physical range is sufficient hydrometer out. For more precise measurement methods, see the keyword analytical test,