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contact angle goniometer
contact angle tester

contact angle goniometer

Model: CAG100/CAG200

Contact angle meters  (also known as optical tensiometers or goniometers) allow direct measurements of surface tension, interfacial tension and contact angles.  Contact angle is an extremely versatile technique used for characterization of both liquids and solids.


The Contact Angle Meter (optical tensiometer) is an ideal industrial or academic tool for product development engineers, R & D engineers who need precision and repeatability.  Contact angle measurement combines high technology test instrumentation and a non-destructive testing method to allow an accurate, objective and repeatable analysis to be made. Using the contact angle meter you can compare the effects of a range of surface treatments and gather data that correlates to various surface conditions e.g. lubricity, wettability, surface energy etc.


UnitedTest CAG series contact angle measuring equipment captures drop images and automatically analyses the drop shape as a function of time. The drop shape is function of surface tension of liquid, gravity and the density difference between sample liquid and surrounding medium. On a solid the liquid forms a drop with a contact angle that also depends on the solid’s surface free energy. The captured image is analysed with a drop profile fitting method in order to determine contact angle and surface tension.

General Introduction

Contact angle meters  (also known as optical tensiometers or goniometers) allow direct measurements of surface tension, interfacial tension and contact angles.  Contact angle is an extremely versatile technique used for characterization of both liquids and solids.


The Contact Angle Meter (optical tensiometer) is an ideal industrial or academic tool for product development engineers, R & D engineers who need precision and repeatability.  Contact angle measurement combines high technology test instrumentation and a non-destructive testing method to allow an accurate, objective and repeatable analysis to be made. Using the contact angle meter you can compare the effects of a range of surface treatments and gather data that correlates to various surface conditions e.g. lubricity, wettability, surface energy etc.


UnitedTest CAG series contact angle measuring equipment captures drop images and automatically analyses the drop shape as a function of time. The drop shape is function of surface tension of liquid, gravity and the density difference between sample liquid and surrounding medium. On a solid the liquid forms a drop with a contact angle that also depends on the solid’s surface free energy. The captured image is analysed with a drop profile fitting method in order to determine contact angle and surface tension.

Key Features

  • Features
  • Standard
  • Structural Features
  • Application and Maintenance
  • Advantages

CAG100 is economical model, with manual table, manual sample feeding system.


CAG200 is senior model, with 360 degree working table, automatic sample feeding system, more test method, Sessile drop, Solid surface energy, pendant drop, Rotate falling, Insert method etc.,

ASTM D7334 Standard Practice for Surface Wettability of Coatings, Substrates and Pigments by Advancing Contact Angle Measurement;

ASTM D7490 Standard Test Method for Measurement of the Surface Tension of Solid Coatings, Substrates and Pigments using Contact Angle Measurements;

ASTM D5946 Standard Test Method for Corona-Treated Polymer Films Using Water Contact Angle Measurements;

ASTM C813 Standard Test Method for Hydrophobic Contamination on Glass by Contact Angle Measurement;

ASTM G205 Standard Guide for Determining Corrosivity of Crude Oils;

ISO 15989 Plastics -- Film and sheeting -- Measurement of water-contact angle of corona-treated films;

ISO 27448 Fine ceramics (advanced ceramics, advanced technical ceramics) -- Test method for self-cleaning performance of semiconducting photocatalytic materials -- Measurement of water contact angle;

TEN201:

★Mainly consist in platinum ring, platinum torsional wire, differential sensor and data processing system etc.

★Easy to operate, high accuracy, auto calculate the liquid surface or interface tension value;  

★Digital display the load; Measuring tray auto up and down; Automatic one key adjust Zero point function;  

With peak value holding function; Automatic stop when the liquid film break; 

TEN202:         ★Mainly consist in platinum ring, platinum torsional wire, differential sensor and data processing system etc.

★Easy to operate, high accuracy, auto calculate the liquid surface or interface actual tension value;  

automatic calculate actual average tension value. 

★LCD display the load; Measuring tray auto up and down; Automatic one key adjust Zero point function;   

With peak value holding function; Automatic stop when the liquid film break;   

★ With peaking value holding indication function; 

with tray up and down indication function; 

with auto zeroing indication function.



Application Scenarios
This instrument is suitable for testing the tension at liquid-air interfaces (surface tension) or between different liquids (such as oil-water interfaces). In the power industry, it can be used for insulating oil quality monitoring; in the chemical industry, it can analyze solution properties; and in educational settings, it can intuitively demonstrate the forces between liquid molecules. Its purely mechanical structure makes it highly durable and easy to maintain, suitable for long-term use.

Operation and Maintenance
Before use, the level must be adjusted, and the platinum ring should be raised and lowered using the worm gear handle. After measurement, the platinum ring and sample container should be cleaned promptly, and the torsion wire should be stored in a relaxed state. The instrument does not require complex calibration; regular lubrication of the mechanical parts is sufficient to maintain performance. The specially designed lever frame structure effectively reduces operational errors.


Factors Affecting Measurement Accuracy

Although the interfacial tension meter is a high-precision measuring device, the measurement results may still be influenced by certain factors. For example, the liquid's temperature, purity, and the stability of the measurement environment can all affect the results. Therefore, when performing measurements, it is necessary to strictly control these variables to ensure the accuracy of the results.

1. The ring method testing uses a scientifically calibrated tension value. To eliminate errors caused by factors such as the shape and contamination of the platinum ring during ring method testing, the correction uses two standard substances instead of the gravitational method. When the platinum ring is used for a long time, causing shape changes or contamination that lead to testing errors, normal conditions can be restored simply by correction with standard substances, without the need to replace the expensive platinum ring.  
2. An integrated molded casing and precision direct drive mechanism are used, greatly improving the reliability and performance of the instrument. The drive mechanism operates without vibration, providing a physical basis for improving testing accuracy.  
3. The improved torque screw lever structure ensures that the magnetic core movement of the sensor follows a trajectory as close to a straight line as possible, ensuring the linearity of the test. 4. The instrument features an automatic stop function, allowing it to stop automatically when testing surface tension. After the test is completed, the lifting platform will automatically stop moving and display the tension value.  
5. The automatic averaging function can automatically calculate and display the average of multiple test results, reducing the workload and effort required from the operator.

Main Technical Specification

ModelCAG100CAG200
Measuring methodsSessile drop,
Solid surface energy,
pendant drop
Sessile drop,
Solid surface energy,
pendant drop,
Rotate falling,
Insert method (optional)
Analysis methodsθ/2, height measuring, automatic analysis (θ/2), automatic analysis (two base points)
Image shooting methodSingle shot, continuous interval shot, continuous shot
Contact angle measuring range0<θ<180°
Measuring resolution0.01°
Measuring accuracy0.1°
Solid surface energyOwens with 2 liquids
Sample size120*80mm
Sample max. height30mm
Two-dimensional table adjusting rangeUp and down 0-60mm, accuracy 0.01mm
Left and right 0-60mm, accuracy 0.01mm
One-dimensional table adjusting rangeFront and back 0-60mm, accuracy 0.01mm
Sample feeding modeSample injector
1), 100 microlitre, 2 microlitre
2), 10 microlitre, 0.2 microlitre
Sample injector adjusting range13mm, accuracy 0.005mm
Sample injector screw knob adjusting range:0-50mm, adopt high accuracy manual screw rod,
ensure liquid feeding stable and accurate.
Power220V, 50Hz/ 110V, 60HZ
Automatic sample feeding
(standard for CAG200, optional for CAG100)
Software control peristaltic pump, 0.1-50 circle per min. , control time can be free setting.
peristaltic pump flow rate accuracy: 0.0002ml/min.
Min. liquid volume: 0.2uml (Optional for CAG100)
Automatic rotary table
(standard for CAG200, optional for CAG100)
360° Manual/Automatic rotary table, software adjust rotate speed 0.01-50Rpm;    
(Do dynamic contact angle test, internatial allow speed is 0.3Rpm, more slower is better. Slow rotate speed can make the reslut more accuracy.   
Can used to measure dynamic contact angle (advanced angle, receding angle, rolling angle). (Optional for CAG100)
Weight50Kg
Dimension500*350*400mm


Main Accessories

ItemQuantity
Frame1 set
3 million pixel digital camera1 pc
Zoom lens1 pc
Three-dimensional table1 set
Light source1 pc
Sample injector1 set
Computer1 set
English software1 set
360 degree Manual/Automatic rotate table (optional)1 set
Peristaltic pump (optional)1 set
Documents (Manual, packing list, certificate)


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Beijing United Test Co., Ltd.