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What Do You Actually Need To Know About The Fundamentals Of Contact Angles?

Views: 295     Author: Kaylee     Publish Time: 2023-11-15      Origin: Site


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What Do You Actually Need To Know About The Fundamentals Of Contact Angles?

Pretending to be familiar with the technical jargon related to contact angle measurement is simple. Do you really, though? In the production and/or quality assurance process, contact angle testing is a crucial step for sectors including coatings, printing, and oil recovery. Knowing these words well can make it much simpler to select the ideal tool for your business—one that you can be sure will accomplish the tasks you need it to.

This is a test, then: The sessile drop method is how our P-Smart Portable Contact Angle Metre calculates contact angle. You can measure static contact angles with the P-Smart by using the time-dependent approach, and dynamic contact angles by using the captive method. It can also use the dependent drop method to estimate surface tension.

Contact Angle: What Is It?

Let's start with the most basic question: what exactly is meant by the term "contact angle"? The angle at which a drop of liquid first makes contact with a solid surface is referred to as the contact angle. It determines how easily a surface or substrate may be soaked up by liquid. What exactly is wetability, then? It refers to the amount of dispersion that a droplet of liquid shows when it is placed on a surface. On non-wetting surfaces, such as a polished vehicle for example, there would be large drops of water present. The water would spread out across the areas that were already moist.

So how exactly do measurements of the contact angle get taken with contact angle metres? One approach that stands out from the others is called the sessile drop method.

Methods Of Making The Drop

The most often used technique for determining contact angle is the sessile drop method. A camera is used to view the droplet on a substrate, and a syringe pump creates the liquid droplet, which is often water. The contact angle of the droplet on the substrate is identified and determined using software that is attached to the camera.

A sessile drop test can be set up in two different ways. The first is referred to as the "horizontal type" or "general type." To examine the droplet in this instance, the camera is aimed horizontally, parallel to the substrate. [View image] Benchtop contact angle metres are typically equipped with this broad version of the sessile drop method.

Another method is referred to as "vertical type." The camera is pointing downward in this instance, perpendicular to the substrate. An inclined mirror reflects the droplet's image in the direction of the camera. The vertical form of the sessile drop method is employed by the P-Smart Portable Contact Angle Metre.

How does the programme operate to take the readings that will be used in the analysis now that we know how the images are taken?

Static and dynamic contact angle measurements are the two different forms of contact angle measurement. First, let's calculate the static contact angle. The most popular technique for determining static contact angle is the time-dependent method, which is employed by the P-Smart.

Static Contact Angle Tester

The Static Contact Angle Measurement

Using the time-dependent method, the shape of the drop is determined as a function of the passing of time. With the help of the Portable Contact Angle Metre, it is simple to track how the shape of your droplet alters over the course of time. You have the option of executing a series capture, which will take photographs at pre-set intervals, in order to automatically follow the changes, or manually tracking the changes by taking individual pictures of the droplet at whatever frequency you see fit.

Measurement of the static contact angle can be used, for instance, to determine the level of cleanliness present in an area, which is an essential step in the process of fabricating circuit boards and silicon wafers.In order to determine the dynamic contact angle, the P-Smart makes use of a method that is known as the captive approach.

The Dynamic Contact Angle Measurement

In the captive method, the droplet being measured is actively inflated or deflated using the syringe at several points throughout the measurement. A droplet is generated on the surface, and after that, either the syringe is removed from the droplet (in order to measure the contact angle of the liquid retreating) or more water is supplied (in order to measure the contact angle of the liquid advancing).

You might be curious in the difference between advancing and receding contact angles. When the droplet is moving, such as when the substrate is being tilted, the contact angle is said to be advancing or retreating. This can happen for a number of different reasons. Therefore, the angle at which dynamic contact is made.

Increasing Angle Of Contact

The contact angle between a liquid's surface and a solid's surface will decrease as the liquid flows onto the solid. When a droplet is viewed while resting on a surface that is inclined, the angle that can be determined on the side of the droplet that is pointing downhill is known as the droplet's inclination.

Angle Of Receding Contact

The angle created as the fluid is pulled away from the solid is known as the receding contact angle. It is the angle measured on the opposite side of the direction the droplet is going when viewed from a tilted surface.

Contact angle hysteresis, or the difference between an advancing and receding contact angle, is a measure of surface roughness. In coating applications, the roughness factor can be quite important.

Knowing both the contact angle and the liquid's surface tension can be crucial at times. How can the surface tension of the liquid in the syringe be measured using a contact angle metre? To do this, the P-Smart employs a well-liked technique known as pendant drop.

Dynamic Contact Angle Tester

Applying A Contact Angle Metre To Surface Tension Measurements

The measurement of the liquid droplet that is allowed to hang from the end of the syringe is used to quantify the surface tension of a pendant drop. The calculation takes into account the size of the droplet's base, the density of the liquid, and the force of gravity. This is automatically detected and computed by the software of the Portable Contact Angle Metre.

When examining a liquid that is not water, the measurement of surface tension is almost often carried out in conjunction with the measurement of contact angle. It is helpful in determining the impact that different liquids have on the substrate. This can be done by analysing the results.


You can perform contact angle, surface analysis, and surface energy studies with the P-Smart Portable Contact Angle Metre almost anywhere. Do you need to immediately assess how clean your surface is? Completed. How can you measure coating ability on a surface that is too large for a tabletop instrument? Simply place the P-Smart on top.

However, there are other factors to take into account when buying a new contact angle metre in addition to proximity. Certain models of contact angle metres have several technical levels available, and not all of them operate in the same way (the P-Smart, for instance, comes in both an automatic and a manual version). You'll be in a better position to determine whether the metre you're looking at will fulfil your needs if you are familiar with these operational phrases for contact angle metres.

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