Plasma treatment is a widely used way to prepare surfaces for coating, printing, and bonding by increasing their surface wettability. Combined with contact angle and surface free energy measurements, it lets you both optimize treatment conditions and verify surface quality over time.

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Evaluate plasma treatment efficiency with contact angle measurements

Plasma treatment is widely used to prepare surfaces for coating, printing or gluing. By exposing a material to ionized gas, the process alters its surface chemistry in a way that increases surface energy and with it, wettability. This is especially valuable for polymers, which are used in many applications due to their mechanical properties but tend to have low surface free energy and poor initial wettability. With plasma treatment, these materials can be made more receptive to liquids and coatings in a controlled and environmentally friendly way.

To evaluate effectiveness of the plasma treatment, contact angle measurements are typically used. The contact angle - the angle formed where a liquid droplet meets the solid surface - is very sensitive to small changes in surface chemistry. A decrease in water contact angle after treatment indicates improved wettability, while measurements with multiple liquids can be used to calculate surface free energy and its components. Together, these measurements provide a straightforward way to compare different plasma settings, identify optimal treatment conditions, and follow the stability of the treatment over time.

Key benefits of optical tensiometers for studying plasma treatment efficiency

Understanding how plasma treatment affects wettability is the first step - turning that understanding to a repeatable process is the next. When you evaluate plasma treated surfaces with contact angle measurements, you can both optimize the process in R&D and keep it under control in production.

Optimize plasma settings

By measuring contact angles and surface free energy for different plasma gases, pressures, powers and treatment times, you can quickly see which combinations give you the desired wettability, instead of relying on trial and error.

Keep treatment consistent

Small changes in the plasma process can have a large effect on surface properties. Routine contact angle measurements help you detect drifts early and keep the treatment within your specified window.

Track hydrophobic recovery

By following contact angle over time after treatment, you can see how quickly the surface relaxes back toward hydrophobicity and set practical limits for how long you can wait before coating, printing or bonding.

Document surface quality

Contact angle and surface free energy values give you clear, numerical evidence of surface treatment quality, making it easier to communicate with colleagues, customers and regulatory stakeholders.

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Optimize and control your plasma treatment

Below is an example workflow showing how contact angle measurements can be used to optimize plasma treatment and then keep it under control.
  1. Set targets on your surface wettability
    Decide what level of wettability or surface free energy you need for your coating, printing, or bonding step. This can be expressed as a maximum water contact angle, a minimum surface free energy, or both.
  2. Plan your plasma parameter matrix
    Choose a range of gases, pressures, powers, and treatment times that are realistic for your material and equipment. Include both shorter and longer treatments so you can see how the surface responds.
  3. Measure contact angles before and after treatment
    Use water and, when needed, additional probe liquids to measure contact angles on untreated and plasma‑treated samples. This shows how strongly the treatment changes the surface and allows you to calculate surface free energy.
  4. Analyze trends and find the optimal window
    Compare contact angle and surface free energy values across the different plasma settings. Identify the conditions that give you the desired wettability without unnecessary over‑treatment.
  5. Follow hydrophobic recovery over time
    Repeat contact angle measurements at defined times after treatment to see how stable the effect is. Use this information to set practical limits for storage and for the time between plasma treatment and the next process step.
  6. Translate finding into QC criteria
    Based on your optimization work, define simple QC checks with contact angle limits and standard methods. These checks can then be used in production to verify that plasma‑treated parts consistently meet your surface specification.
Determination of optimal plasma treatment time of polypropylene

Case example: Determining the optimal plasma treatment time of polypropylene

Polypropylene (PP) is widely used in medical and technical applications, but its inherently hydrophobic surface leads to poor wettability for many liquids and coatings.

In this case example, PP samples were treated with air plasma for different durations and evaluated with contact angle measurements using three probe liquids. The study illustrates how contact angle and surface free energy measurements can be used to tune plasma parameters and define a robust process window for both development and quality control.

Download Case Study
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Measurements

Our optical tensiometers offer several measurement possibilities to evaluate plasma-treated surfaces and polymers.

Sessile Drop

Contact angle

Batch sessile drop

Surface free energy

Automatic DCA

Dynamic contact angle

Pendant drop

Surface tension

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Theta Lite - your solution for plasma treatment evaluation

Attension Theta Lite is a robust optical tensiometer designed for straightforward, repeatable contact angle measurements. It is ideal for both detailed plasma treatment optimization in R&D and straightforward QC checks in production.

Its durable construction and long instrument lifetime make it a reliable choice for laboratories and production environments where consistent performance and low maintenance are important.

With ready‑made measurement recipes, robust analysis tools, and data handling suited for regulated environments, Theta Lite helps your team translate surface science into reliable, everyday practices.

Discover Theta Lite

Attension Benefits

Quantitative wettability results

Numerical contact angle and surface free energy values instead of subjective dyne pens or water break tests.

Intuitive instruments

Easy to implement in the lab with default measurement recipes in place.

Supports R&D and QC

One platform for process optimization in the lab and routine checks in production.

Robust design and long lifetime

Built for stable performance over many years of daily use.

Reliable, repeatable data that can be trusted and shared

High-quality optics and automated analysis reduce operator dependence & structured reporting supports internal reviews and external stakeholders.

Access to Attension academy

Access to comprehensive learning resources such as tutorials, webinars and white papers.

Plasma treatment opens powerful possibilities for tailoring surfaces - when you can confidently verify its effect on each surface you treat.

By combining plasma processes with robust contact angle and surface free energy measurements, you can optimize your process parameters, control hydrophobic recovery, and secure quality in everyday production.

Contact our team of experts