plating, anodizing, & finishing Q&As since 1989
Tensiometer vs. Stalagmometer Readings (Chrome)
Q. Dear Sirs,
I'm requesting info about the type of tensiometer that we should use in hard chromium platings baths: Du Nuöy Ring or Wilhelmy Plate.
Thanks in advance
SHOP EMPLOYEE - BARRANQUILLA, COLOMBIA, SOUTH AMERICA
October 6, 2023
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Q. Are there automatic stalagmometers (surface tension measuring devices) available for use? If so, where might I locate one? Manual ones are cumbersome and invite erroneous readings. The application is for measuring surface tension of chemical blanket agents design to minimize chrome air emissions.
So much surface tension equals so much chrome emitted ... at least in theory.
Thanks for any input.
A. I don't know, Sandra -- but maybe a reader does. But the American Electroplaters & Surface Finishers Society hosted the 4th Hard Chromium Plating Colloquium (1996) in Cleveland, and here is an abstract of one paper:
- "Conducting Surface Tension Measurements for Compliance with Chromium MACT Standard
Joelie Hill, Scientific Control Laboratories, Chicago, IL
Conducting surface tension measurements to consistently meet 45 dynes/centimeter is a compliance option for decorative chromium plating facilities under the U.S. EPA's National Emission Standards for Chromium Emissions (the MACT Standard). It is important to understand the various techniques and procedures for measuring surface tension in order to find a suitable method for your facility. This paper will cover methods with tensiometers (DuNouy ring and Wilhelmy plate), stalagmometers, capillary tubes, and various other methods..."
You could see if the proceedings are available. AESF / NASF (www.nasf.org) conducts periodic seminars on chrome compliance too.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. The stalagmometer measures the number of drops coming from a known orifice to calculate the surface tension. KSV Instrument (now "Attension" by KSV Instruments) makes an AL-20 drop volume tensiometer based on the stalagmometer principle. It is an automatic stalagmometer.Greg Wills
- Linthicum Heights, Maryland, USA
June 8, 2010
Q. My question is about decorative chrome bath surface tension, as measurements with a stalagometer relate to measurements with a tensiometer.In addition to the Ann Arbor Mi. study, I've done testing on my baths. If anyone else has done this, and has supporting documents could you please contact me. My results show a definite difference, and that the amount of difference relates directly to the amount of metal impurities. Any input would be welcome. Thank you LayneLayne Hilliard
- Killeen, Texas
Q. I am having trouble getting accurate surface tension measurements on a chromic acid anodizing bath using a tensiometer. Calibration with a known weight goes fine, but doing surface tension tests on DI water turn out 5-10 dynes/cm low. Results from the anodizing bath also seem low 18-24 dynes/cm. The bath's operational parameters are 26-40 dynes/cm, and stalagmometer readings are consistently in the mid 30's. I am using sterile petri dishes for sample containers, and I am cleaning the tensiometer ring in acetone [adv: item on
Amazon] with a DI rinse and then flaming the ring with a lighter until red-hot as the tensiometer instructions stipulate. The chromic acid and DI water samples are cooled to room temperature (25 °C). I would normally assume that the stalagmometer is just reading high, but the DI water tensiometer readings are low also, so I think the problem is with the tensiometer.
I read somewhere that tensiometer and stalagmometer readings on the same sample differ by 10-20 dynes/cm (the stalagmometer reading the higher). Has anyone else run into this difference also? Are there any suggestions for normalizing the two readings? Any information would be appreciated.
- Plymouth, Michigan, USA
A. The best info I've seen on the subject is "Report on Observed Differences in Dynes/Centimeter Readings of Various Chromium MACT Method 306B Surface Tension Measuring Devices" by J. Hensley and David York, presented at AESF Week in 1997.
Upshot is that there is a differences, the magnitude of the difference depends upon the surface tension, and the difference changes with solution.
James Totter, CEF
- Tallahassee, Florida
Not sure of guidelines in your state, but in California the guidelines for each are different.
According to the CA EPA Air Resources Board reference, #93102.8-Chemical Fume Suppressants
"In the performance testing, the hexavalent chromium emission rate of 0.01 milligrams per ampere-hour was achieved under conditions in which the surface tension did not exceed 45 dynes/cm by a stalagmometer or 35 dynes/cm by a tensiometer."
There seems to be 10 dynes difference in the measurement reading. Personally I use a stalagmometer; it's quite simple and little maintenance.
Chrome Plating - Stockton, California, USA
If we have sample which have viscosity in range of 2 to 8 dyne/cm and it is suspension like sample than what method you suggest for measurement of surface tension? Please provide me a guidance.
pharmaceuticals. - Ahemdabad, Gujarat, India
A. I have developed an instrument
"SURVISMETER" measures both the viscosity and surface tension together with single instrumental unit.
chemistry research lab. - New Delhi, India
A. Stalagmometer surface tension drop count method Tubes are available in 2.5mL, 3.5mL and 5.0mL sizes.
Stalagmometer for Nickel, Acid Copper, Acid Zinc, Acid Dips and Pickles (5 ml)
Stalagmometer for Chromium (2.5 ml)
Stalagmometer Kit (includes: stand, filler bulb, beaker and counter) for Nickel, Acid Copper, Acid Zinc, Acid Dips
Stalagmometer Kit (includes, same as above) for Chromium
Stalagmometer surface tension drop count method
Surface tension has long been recognized as an important physical characteristic of fluids and colloids that can affect biological processes. Scientists sought ways to measure this phenomenon, but reproducible results were difficult to obtain. Two approaches, developed to measure this subtle force, are displayed here.
The process of drop formation by liquids is, in part, controlled by the surface tension of the fluid. To determine surface tension, the stalagmometer used a drop weight method, in which the number and weight of drops were compared to those from a reference liquid. Seemingly simple, the stalagmometer nevertheless required considerable skill and absolute cleanliness for readings to be meaningful.
(Engineering): "An instrument for measuring the size of drops suspended from a capillary tube, used in the drop-weight method. Also known as stactometer; stalogometer. Tubes are available in 2.5mL, 3.5mL and 5.0mL sizes."Tim Wong
- Boca Raton, Florida, USA
March 17, 2008
A. Surface tension and interfacial tension are the functions of the cohesive forces. For example mercury has surface tension 465 dyne/cm at 25 °C while the water has 72.18 dyne/cm. This difference is because the Hg has highest cohesive forces but the water 6.44 times lower than of the HG.
Thus the difference in surface tension is function of nature of the molecule.
On the other hands the viscosity is a function of frictional forces which are created by the solid surface of the capillary with respect to liquid molecules flowing along capillary walls.
- Gandhinagar, India
May 16, 2011
A. This is easy. Dynamic (flowing) drops will always be heavier than tensiometer readings. This is because as the stalagmometer drop is separating, a finite time for this, it is being filled with additional fluid making it heavier. This is the holy grail, and I will be publishing a way to compare the two methods.Chuck Cronan
- Milwaukee, Wisconsin, USA
September 27, 2011
A. The use of survismeter is safer and resource saving along with most accurate results.Man Singh [returning]
- Gandhinagar Gujarat, India
May 1, 2017
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