This article is part of our “Coating A–Z” series. While the German version appears under “B for Benetzung”, the English equivalent uses “W for Wetting” – same topic, different alphabet. Because in surface science, understanding wetting is essential – no matter the language.

 

Bonding A–Z: How Wetting Works – and What It Depends On

Good wetting occurs when the surface energy of the solid is higher than the surface tension of the liquid. In practice, this means the liquid spreads out over the surface instead of forming droplets. At Neschen Coating, we understand that proper wetting is a key factor for product quality.

Whether a liquid can wet a surface effectively depends primarily on the interplay between two forces:

• Surface tension of the liquid
• Surface energy of the solid substrate

A simple measure for wetting behavior is the contact angle formed by a droplet on a surface. The smaller this angle, the better the wetting – and the better the conditions for a successful coating or adhesive bond.

 

Why Is Wetting So Critical in Coating Processes?

Insufficient wetting can lead to serious issues – from uneven coating layers and poor adhesion to premature failure during use. Especially in functional or high-performance applications, this is simply not acceptable.

Examples of wetting-related requirements:

• Adhesives must spread evenly across the substrate to ensure strong, durable bonds.
• Technical coatings, such as those used on protective films or print media, require defined spreading characteristics for subsequent processing (e.g., printing, lamination).

 

Optimizing Wetting – Precisely Controlled Using Additives

In most cases, surfaces do not naturally provide ideal wetting conditions. That’s why wetting needs to be specifically enhanced – for example, by:

• Chemical additives known as surfactants (or wetting agents), which reduce the surface tension of the liquid
• Surface pretreatment of the substrate, such as corona or plasma treatment, to increase its surface energy
Surfactants in adhesives ensure even spreading across the target surface – even on critical materials like plastics or coated papers.

 

Wetting at Neschen Coating – Expertise Meets Process Reliability

In our coating processes – whether for self-adhesive systems, specialty films, or textile solutions – we place the highest value on precisely tuning all relevant parameters:
• Careful selection of raw materials and additives
• Formulation adjustments tailored to the substrate
• Inline monitoring and testing of wetting behavior during production
• Continuous R&D to improve adhesion and spreading characteristics

The result: functional, durable, and visually flawless products that perform reliably in their applications – from architectural films to professional media solutions.