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Dyne Testing is a quality testing method used in many industries as a way to check a material surface and characterise how it will react with manufacturing processes.
Most commonly Dyne Testing is used to determine the dyne level, also known as the surface energy of a material and the material readiness for bonding, printing, painting and coating. Dyne level is usually measured in Dynes/cm or milli newtons per meter (mN/m).
Many materials do not have the right surface energy and this can lead to poor performance with these processes. A low surface energy can be an indication of contamination on the material, or lack of surface treatment and preparation. A high surface energy can be a check that a process such as plasma or corona treatment has taken place.
Common Material Surface Energy Examples
All materials have a surface energy and it is this energy that we measure to determine the materials ability to interact with the world around it – most commonly and sensibly with liquids.
A few typical values for materials can be found in the table below, alongside some expected values of materials after a surface treatment such as plasma treatment.
| Material | Untreated Surface Energy (mN/m) | Expected Treated Surface Energy (mN/m) |
| PTFE | 19 | 40 to 60 |
| Polypropylene (PP) | 30 | 60 to 72 |
| Polyethylene (PE) | 30 | 60 to 72 |
| Nylon (PA6, PA66) | 38 | 72+ |
| Acrylic (PMMA) | 40 | 72+ |
| Glass | 34 | 72+ |
| Stainless Steel | 32 | 72+ |
These numbers are the start of understanding your material and how why they matter to you on your process. It might be the case that your printing process gives the performance needed when the dyne testing shows a pass at 38 dynes. While an adhesive applied to the same material later on needs 48 dynes to get the right performance.
Dyne Testing isn’t a promise that your process will work and there isn’t a golden number to pass at. But it’s a great indicator and once you understand your material and your process, you can implement a strong quality test procedure.
How Do You Perform Dyne Testing?
There are a few methods for dyne testing, but the most common techniques referred to in this way are Dyne Pens and Dyne Test Inks.
These are simple liquids that come in a range of values and the simple test is to see whether the liquid beads up or flows and wets the surface. A material with a high surface energy will pull the liquid down so it wets the surface. A surface with low energy won’t be able to pull the liquid down and the liquid will bead up.
You use the different levels to find out how your material measures.
Dyne pens are the usual suspect for dyne testing because they’re quick and easy to use, don’t need any swabs or equipment and are relatively cheap as a test method. The liquid in the ink bottles and the pens are the same, however, pens risk contamination by rubbing the nib over a dirty surface while the ink bottles use single use disposable swabs so for oily or greasy surfaces, test ink bottles with swabs are best for dyne testing.
For a quick example, see the video below for a dyne testing experiment using Dyne Test Inks.
Common Applications for Dyne Testing
Dyne Testing will tell you the surface energy of a material, here are a few common situations where you can find this kind of testing useful
| Problem to Test | Expected Results |
| Corona treated polythene for printing | Polythene (PE) will likely start around 30 dynes and get good adhesion above 38 dynes. This is the classic example of solvent based printing onto materials being converted in to plastic bags. |
| Plasma treated polypropylene for adhesive bonding | Polypropylene (PP) will likely start around 30 dynes and for strong solvent adhesives may need a similar 38 dyne level, but many water based or UV adhesives might need over 50 dynes. |
| As received rolled or pressed metals | A lot of metals covered with processing oils will give odd surface energy results because you’re trying to test the dyne level of a fluid on the surface rather than the solid metal. But in most cases the metal will have a high dyne level and the oils will be very low. A test value in the 30s is often sensible. |
| Flame treated metals | A treated metal that has no contamination, oils or greases on is likely to be very high. The textbook value of surface energy for many pure metals is in the 100s so high level dyne inks show a big change between oily and finished products. |
| Material uniformity for coating | In many situations, you might find that you have a high surface energy and dyne testing passes at the right level, but you still see imperfections and inclusions in a finished coating. You can use a drawdown bar, or spread the inks to check large areas and look for splashed contamination that could cause problems like fish eyes in the finished coating. |
We normally measure up to 72 dynes for dyne testing, which is a sensible figure as most things will have excellent properties at this value. In reality, metals especially can go much higher and be many hundreds, if not thousands of dynes if perfectly clean but especially with metals, glass and ceramics if they are that clean they will want to bond to something and may readily oxidise or grab hold of airborne contamination.
Alternatives to Dyne Inks for Dyne Testing
Dyne inks and pens are a quick, relatively cheap way of measuring surface energy and require very little training, but they can be subjective and the use of chemicals on a production line may not be perfect for some manufacturers.
The key alternative to inks are systems called Optical Tensiometers; also known as contact angle meters or goniometers. These systems are often more expensive and require a well trained operator, however they give much more accurate and repeatable information and are highly used in universities and quality assurance labs. Benchtop and mobile contact angle meters are available.
These systems place a droplet of a known liquid onto the surface of your material and measure the interaction by measuring its angle of contact at the edge of the droplet. A high contact angle, with the droplet looking like a ball on the surface gives a low surface energy, while a droplet that wets the surface has a low contact angle and a high surface energy.
These systems measure the drops very accurately, normally to multiple decimal places and provide an accurate and repeatable measurement as a documented number. Several measurements can be taken and you can use different liquids to get additional information about the surface.
Buy Online and Find Out More
Ebble Group manufacture and supply various dyne testing products and the simple Dyne Pens and Dyne Inks are available to buy for next working day shipment from Ebble.Shop – our central online shop resource.
We also supply Contact Angle measuring devices and Force Tensiometers if the more technical route is for you.
If you’re not sure that Dyne Testing is for you and want to explore more, then there are two options:
- Get in touch – we offer a free lab service for checking materials and offering initial support so you know you’re getting the right levels, the right ink type and one that works with your process.
- Read our buyers guide for Dyne Pens and Dyne Inks to go in to more detail.
