What Is a Dyne Pen?
A dyne pen is used to measure the wetting characteristics (surface tension, dyne level) of an object’s surface.
It is sometimes referred to as a tension checker or wettability check pen. The dyne level indicates the adhesion properties of an object’s surface. Using a dyne pen, you can assess how well an ink, varnish, primer, etc., adheres to the surface of materials such as plastic or metal. It is characterized by its ease of use, similar to a highlighter pen.
Uses of a Dyne Pen
Overview
Dyne pens are used to measure the surface tension and wetting properties of various materials, as well as to measure surface energy values. They are particularly prevalent in industrial fields requiring printing, painting, and adhesion. Examples of major applications include:
- Measurement of the surface tension of plastics and other non-porous substrates.
- Checking the surface condition (printability) of objects before printing.
- Assessing the condition of objects after various types of cleaning, such as light cleaning.
- Confirming adhesion and affinity of surfaces of materials after treatments like plasma surface treatment (PE, PP, plastic films, etc.)
- Testing for oil residue after degreasing and cleaning of metalworking parts.
The main areas of application include:
- Automotive interior and exterior parts
- Electronic devices and components
- Resin and ceramic products
- Manufacturing and R&D departments of steel, nonferrous metals, etc.
- Various types of printing (gravure printing, offset printing, UV printing, screen printing, pad printing, inkjet printers)
- Dry laminators, extrusion laminators
- Inflation film, T-die film sheet, stretched film
- Coating
Principle of a Dyne Pen
What Is Wettability?
Wettability is the affinity between a liquid and a solid surface. It is evaluated based on how uniformly a liquid spreads on a solid surface due to intermolecular forces, termed “high wettability.”
Wettability is related to surface tension, primarily determined by the surface energy of the liquid and solid. For a liquid to spread on a solid surface, the surface energy of the liquid must be less than that of the solid. Thus, the higher the surface energy of the solid, the better the wettability. Surface energy is also referred to as dynes, measured in mN/m (millinewtons per meter) in the SI system and dyn/cm (dynes per centimeter) in the CGS system.
This index measures how well substances like inks, glues, and varnishes adhere to surfaces of materials such as plastics or metals.
How to Measure Wettability with a Dyne Pen
The dyne pen is available in pens for each number of dynes, allowing precise measurement. The method is as follows:
- Apply the test pen of the desired dyne number to the material’s surface.
- Observe the state of the liquid film approximately 2-4 seconds after application to determine suitability. If there is no breakage or shrinkage of the liquid film, the test is successful, and you should test with a higher number of dynes to determine its suitability. Conversely, if the liquid film breaks or shrinks, test with a lower number of dynes.
- Repeat the above steps, and the highest number of dynes that does not cause breakage or shrinkage of the liquid film is the dyne level of the material’s surface.
Components of a Dyne Pen
Formamide is commonly used as a component of dyne pens. However, non-toxic and non-irritant alternatives without formamide are also available.
Types of Dyne Pens
Dyne pens are typically sold in sets of about 4 to 8 pens of different dyne numbers. The 30s and 40s dyne numbers are most commonly used, but pens with dyne numbers in the 50s, 60s, and 70s are also available.
Ink colors include red, blue, and green. In addition to regular capacity types (e.g., 50 mL), smaller quantity types (e.g., 10 mL) are available for quick use. Some products are non-toxic and non-irritant, free from formamide and other harmful organic compounds. However, it is necessary to review the material safety data sheet (SDS) for those containing substances like xylene or formamide.