Dropping point
The dropping point of a soap-thickened lubricating grease
Grease (lubricant)
The term grease is used to describe semisolid lubricants. Although the word grease is also used to describe rendered fat of animals, in the context of lubrication, grease typically applies to a material consisting of a soap emulsified with mineral or vegetable oil...

 is the temperature at which it passes from a semi-solid to a liquid state under specific test conditions. It is an indication of the type of thickener used, and a measure of the cohesiveness of the oil and thickener of a grease.

Dropping point is used in combination with other testable properties to determine the suitability of greases for specific applications. It is applicable only to greases that contain soap thickeners. Greases with other thickeners, such as many synthetic greases, do not change state. Instead, they separate oil, and the dropping point as a phase transition does not apply.

ASTM test procedure

The dropping point test procedures are given in ASTM
ASTM International
ASTM International, known until 2001 as the American Society for Testing and Materials , is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services...

 standards D-566 and D-2265. The test apparatus
Apparatus may refer to:*Technical term for body of the Soviet and post-Soviet governments *Machine*Equipment*Critical apparatus, the critical and primary source material that accompanies an edition of a text-See also:*Fire apparatus...

 consists of a grease cup with a small hole in the bottom, test tube, two thermometer
Developed during the 16th and 17th centuries, a thermometer is a device that measures temperature or temperature gradient using a variety of different principles. A thermometer has two important elements: the temperature sensor Developed during the 16th and 17th centuries, a thermometer (from the...

s, a container, stirring device if required and an electric heater. The inside surfaces of the grease cup are coated with the grease to be tested. A thermometer is inserted into the cup and held in place so that the thermometer does not touch the grease. This assembly is placed inside a test tube. The test tube is lowered into the container which is filled with oil
An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....

 in D-556 and has an aluminum block in D-2265. Another thermometer is inserted into the oil/block.

To execute a test, the oil/block is heated, while being stirred, at a rate of 8 F-change to 12 F-change per minute until the temperature is approximately 30 F-change below the expected dropping point. The heat is reduced until the test tube temperature is 4 F-change or less than the oil/block temperature. Once the temperature has stabilized the sample is inserted. The dropping point is the temperature recorded on the test tube thermometer, plus a correction factor for the oil/block temperature, when a drop of grease falls through the hole in the grease cup. If the drop trails a thread, the dropping temperature is the temperature at which the thread breaks.
D-2265 explains that the dropping point is useful to assist in identifying the type of grease, and for establishing and maintaining benchmarks for quality control. It adds that the results are not sufficient to assess service performance because dropping point is a static test.

Other test procedures

Equivalent to D566 and D2265:
  • IP 132
  • ISO
    International Organization for Standardization
    The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...

     2176:1995 Petroleum products—Lubricating grease—Determination of dropping point
  • DIN
    Deutsches Institut für Normung
    is the German national organization for standardization and is that country's ISO member body. DIN is a Registered German Association headquartered in Berlin...


  • National Standard of People’s Republic of China GB/T 4929 “Test Methods for Dropping Point of Grease”
  • S 1448(P-52)
  • GOST
    GOST refers to a set of technical standards maintained by the Euro-Asian Council for Standardization, Metrology and Certification , a regional standards organization operating under the auspices of the Commonwealth of Independent States .All sorts of regulated standards are included, with examples...

     7134-73, Method B
  • JIS
    Japanese Industrial Standards
    Japanese Industrial Standards specifies the standards used for industrial activities in Japan.The standardization process is coordinated by Japanese Industrial Standards Committee and published through Japanese Standards Association.-History:...

    K2220:2003 Lubricating grease
  • DIN 51801 Dropping Point of Lubricating Grease
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