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S90 Zahn Viscosity Cups

Article No. 13579

S90 Signature Zahn Viscosity Cup #4

  • S90 Signature Series Zahn Viscosity Cup #4
  • Download Excel Viscosity Chart HERE

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$166.00 excl. taxes & shipping cost


  • The S90 Zahn Dip Viscosity Cup is an improved version of the time honored Zahn Signature Series Viscosity Cup.
  • It is an all stainless steel calibrated Viscosity Dip Cup, and qualifies for certification under ANSI/NCSL Z540 or ISO/IEC 17025, ISO 9001, as applicable.
  • GARDCO is the only producer authorized to use the Zahn name and has added the S90 designation to identify the improved viscosity cups manufactured on new state-of-the-art equipment to insure optimum quality and uniformity. Calibration of the S90 Zahn Dip Cup matches the earlier Zahn Signature Cup.
  • Conversion formulas and tables relating flow cup efflux time in seconds to viscosity in centistokes are identical for both series of viscosity cups.
  • S90 Zahn cups are calibrated with standard "G" series oils traceable to the National Institute of Standards & Technology (NIST).
  • "G" series Canon calibration oils (standards) are produced in accordance with ISO 9002.
  • NOTE: Efflux time from these viscosity cups does not meet ASTM specifications. Tables are available for converting S90 Zahn cup efflux time to EZ™ Zahn cup efflux time which complies with ASTM D4212.
  • Viscosity Cup flow characteristics are defined by a mathematical formula and standard “G” series Canon Calibration oils.
  • Furnished with each S90 Zahn dip cup is a conversion table relating cup efflux time to the nearest tenth of a second to viscosity in centistokes.
  • S90 Zahn Viscosity cups, with the above advantages, cannot be confused with other, lesser defined cups as they are produced, calibrated and sold only by Paul N. Gardner Company and authorized dealers.
  • Ransom & Randolph recommends the S90 Zahn Viscosity Cups as the most reliable viscosity cups to measure and control the consistency of ceramic shell slurries.
  • S90 Zahn Dip cups do not meet ASTM Specification D4212. Not all S90 Zahn Cups deviate from the standard by the same amount - the range being from near compliance to a variance exceeding a factor of two. Manufacturing procedures include calibration with oils traceable to the National Institute of Standards and Technology (NIST). Certification with compliance to ANSI/NCSL Z540 or ISO/IEC 17025, ISO 9001, as applicable, is available at our Gardco Service Department. Tables are available which convert between S90 Zahn Signature and EZ™ cups of the same number, to the nearest tenth of a second, to assist those who need to work with both established standards.

Technical Attributes

  • Data
    Item NumberCup No.Seconds RangeCentistoke Range
    13573131 to 6015 to 78
    13575219 to 6039 to 238
    13577311 to 6063 to 604
    13579410 to 6097 to 899
    13581510 to 60219 to 1627
    Certificate of Calibration available at additional charge for all cups.
    Cup No.Efflux Time Seconds “T” from Centistokes “V”Centistokes “V” from Efflux Time in seconds “T”
    1T = (V + √ (V2 + 6805) ) ÷ 3.18V = 1.59T - 1070 ÷ T
    2T = (V + √ (V2 +12707) ) ÷ 8.36V = 4.18T - 760 ÷ T
    3T = (V + √ (V2 + 23529) ) ÷ 20.46V = 10.23T - 575 ÷ T
    4T = (V + √ (V2 + 32983) ) ÷ 30.26V = 15.13T - 545 ÷ T
    5T = (V + √ (V2 + 58903) ) ÷ 54.54V = 27.27T - 540 ÷ T
    Note: Furnished with each cup is a conversion table for each tenth of a second within the cup range.
    Catalog NumberOil NumberUse With Cup NumberNominal Centistokes* at 25°C., 77°F.
    13653G-3504 and 5880
    *Certified value is printed on container label. Note: A graph is furnished with each cup showing efflux time of the "G" oil from 20 to 27 degrees Celsius.

    These standard oils prepared expressly by the Cannon Instrument Company for the Paul N. Gardner Company are produced in accordance with ISO/IEC 17025:2005, ISO/IEC Guide 34:2009, ISO 9001:2008.

    Caution: Silicone fluids should not be used to calibrate viscosity cups. These materials change the interface between the cup surface and the test material and therefore change the cup calibration. The following is taken from ASTM D445: Viscometers used for silicone fluids should be reserved for the exclusive use of such fluids. Solvent washings from these viscometers should not be used for cleaning other viscometers.

More Information

Viscosity Cups are non-returnable items. Subject to final sale.

S90™ is a Registered Trade Mark of the Paul N. Gardner Company, Inc

Viscosity Cup Care

GARDCO produced and calibrated S90 Zahn viscosity cups are made of stainless steel except for the name plate. These cups will give years of satisfactory service requiring only thorough cleaning following each use. Even so, it is good practice to periodically confirm cup calibration. This is easily done with use of appropriate “G” oil listed in the Calibrating Oils table. Centistoke label value of the oil is traceable to the National Institute of Standards and Technology.

Guide for removing the G-series calibrating oil from Gardco viscosity cups.

Any remaining material in the cup must be removed by flushing with a suitable solvent. Light naphtha, heptane, octane, highly aromatic solvents, and or any other petroleum-derived hydrocarbon solvent can be used. Varsol® is a commercial solvent that works very well for this purpose. Varsol is a registered trademark of the Exxon Company

Completely dry the viscosity cup with a lint free cloth. Use a highly volatile solvent for a second cleaning as since any remaining hydrocarbon solvents from the first process will evaporate quickly after the sample has been flushed from the cup. Hypersolve, MEK and Alcohol can be used in aluminum cups and Hypersolve and Alcohol for the stainless steel cups. Acetone is commonly used as the second solvent because of its high volatility and its ability to dissolve traces of petroleum solvents and water.

In the third process a low velocity stream of clean air will be sufficient to evaporate remaining traces of any volatile solvent. Be aware, avoid rapid evaporation of these solvents as this can cool the surface to such an extent that humid air may be brought below the dew point, causing a film of water to form on the cup.


Equivalent Charts cover Gardco Calibrated Viscosity Cups and are based on conversion formulas of a type & with parameters as referenced in The Encyclopedia of Polymer Science & Engineering (Vol. 4, Second Edition, John Wiley & Sons, Inc.). Standard oils traceable to the National Institute of Standards & Technology were used in experimental development of these formulas.


  1. Select the cup to be used from the Range Specification table.
  2. Insure that the cup is clean, especially around the orifice.
  3. Adjust temperature of the material to be tested, if necessary.
  4. Holding the cup by the ring, immerse it into the test material.
  5. Measure and record temperature of material encompassed by cup.
  6. Hold cup vertically by inserting index finger into handle ring. In a quick, steady motion, lift the cup out of the sample material, starting the timer when the top edge of the cup breaks the surface. During the flow time, hold the cup no more than 6” above the level of the sample material.
  7. Stop the timer when the first definite break in the stream at the base of the cup is observed.
  8. Record cup name, number and efflux time in seconds with temperature. As an option to the preceding step, refer to the Insta Visc viscosity calculator Insta Visc App or conversion table for the cup to determine the centistoke viscosity for the measured efflux time in seconds and record this value and the measured temperature.
  9. Promptly clean the cup taking care not to abrade orifice. Use a length of nylon fishing line to clean the orifice.



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