This International Standard specifies several methods for the empirical estimation of the consistency of lubricating greases and petrolatum by measuring the penetration of a standardized cone.

The National Lubricating Grease Institute (NLGI) classifies greases according to their consistency, as measured by the 60 strokes worked penetration. The NLGI classification includes nine consistency numbers or grades, each grade corresponding to a given range of worked penetration. The NLGI classification is given in ISO 6743-99.

Clause 7 of this International Standard specifies four procedures for determining the consistency of lubricating greases by measuring the penetration of a full-scale cone. These procedures cover the measurement of unworked, worked, prolonged worked, and block penetrations. Penetrations up to 500 units can be measured.

Clause 8 of this International Standard specifies methods for determining the consistency of lubricating greases when only small samples are available, by the use of cones a half-scale or quarter-scale of that used in Clause 7. The methods are applicable to greases having penetrations of 175 units to 385 units with the fullscale cone and are intended for use only if the size of the test sample prevents the use of cones described in Clause 7. They are not intended to replace the full-scale penetration as described in Clause 7, although a conversion to full-scale penetration is given in 10.2. See 8.1 for the limitations on the use of one-quarter-scale cones due to the poor precision.

NOTE 1 Unworked penetrations do not generally represent the consistency of greases in use as effectively as do worked penetrations. The latter are usually preferred for inspecting lubricating greases.

NOTE 2 Penetration of block greases can be obtained on those products that are sufficiently hard to hold their shape. These greases generally have penetrations below 85 units.

Clause 9 of this International Standard specifies a method for the determination of the consistency of petrolatum by measurement of the penetration of a full-scale cone, having penetrations up to 300 units. This method can also be used to estimate the consistency of slack waxes.