ASTM D4212 Standard Test Method for Viscosity by Dip-Type Viscosity Cups
6. Apparatus
6.1 Zahn Viscosity Cup - No. 1 through No. 5 Zahn viscosity cups made of corrosion- and solvent-resistant materials. The nominal capacity of the cup is 44 mL, but may vary from 43 to 49 mL, depending on the manufacturer. A diagram of a Zahn cup is given in Fig. 1. The dimensions, including orifices, are only approximate because the cups are not made to a uniform specification. Each manufacturer produces a different cup and considerable variation between batches from some manufacturers has been noted in the past. This is a major reason why Zahn cups should not be referenced in specifications between producer and user only when controls sufficient to ensure adequate cup-to-cup and operator-to-operator comparison are included. (See Appendix X1 for additional information on Zahn Cups.)
NOTE 1 - The various cup numbers are for identification of the viscosity ranges within the series only and should not be used for comparison between different kinds of cups, that is, a No. 2 Zahn cup has no relationship whatsoever with a No. 2 Shell cup.
6.1.1 Nominal Zahn cup orifice diameters are listed in Table X2.1. Cup No. 1 with the smallest orifice is used for determining the viscosity of thin-bodied materials. Cup No. 2 is for use with clears, lacquers, enamels, and press-side adjustment of flexographic inks; cups Nos. 3 and 4 are for use with more viscous paints and inks (No. 3 for manufacturing of flexographic inks); and cup No. 5 is used for silk screen inks.
6.2 Shell Viscosity Cup - No. 1 through No. 6 Shell viscosity cups made of stainless steel with a capacity of 23 mL and a 1-in. (25-mm) long capillary in the bottom and conforming to the dimensions shown in Fig. 2.
6.2.1 Nominal Shell cup orifice diameters are listed in Table X2.1. Cup Nos. 1 through 2 1/2 are recommended for use with reduced rotogravure inks; No. 2 is for use with flexographic inks; Nos. 3 through 4 are used for industrial enamels, lacquers, flexographic, and gravure inks; Nos. 5 and 6 are used for heavy materials.
6.3 Calibration Thermometer - ASTM Saybolt Viscosity Thermometer 17F having a range of 66 to 80°F and subdivisions of 0.2°F, or 17C having a range of 19 to 27°C and subdivisions of 0.1°C, both conforming to the requirements of Specification E 1. Thermometers having subdivisions other than these may be used depending on the sensitivity of the material to be tested, the demands of the application, and the agreement between the purchaser and seller.
6.4 Timer - Any timing device may be used provided that the readings can be taken with a discrimination of 0.1 s or better.
