Table of Contents
What To Expect In This Buyers Guide
There are a few key considerations when looking to measure surface energy, here we will explore:
- The difference between Dyne Pens and Dyne Test Inks
- What Dyne Level do you need?
- Type A, Type B, ISO 8296 and Safety Considerations
- Other surface energy test methods
- Support from Tantec and Ebble Manufacturing
First, a quick introduction video to show how measuring is done using test pens (which is the same as test inks)
Dyne Pens vs Dyne Inks
The first question is usually inks vs pens.
Inks use single-use wooden swabs, so any contamination on the surface stays with the swab and isn’t put back into the bottle. This is by far the most versatile way of measuring and is best for exploring the world of surface energy without worrying about contamination. This also makes the bottles best for situations like metal testing where oils and fluids are routinely present.
Felt nibbed pens are handy, quick to use and easier to transport around, but their major drawback is contamination of the nib. If you run the pen over dirty materials, you will contaminate the nib and it will distort your readings. If your surface is mostly clean, it shouldn’t be a problem and if you’re replacing the pens frequently, they’re a sensible way to go.
Both inks and pens contain the same liquids, and their cost per ml is the similar, however, pens are 15ml and bottles are 30ml so inks do cost more over the same range.
What Dyne Level Do I Need?
Deciding which levels to use depends on the material you have, the treatment or process you’re checking and the requirements you need.
Testing is normally done for one of three reasons:
- Test base material quality
Checks on incoming goods to ensure they’re starting where they should can be important, especially if a part should be ‘clean’ as received. Testing incoming quality on items such as rolls of steel is a common use. - Test a process, such as cleaning, plasma or corona treatment
If a part has been through its process before printing or bonding, it’s useful to know that the dyne levels are being achieved and that there isn’t a problem with the process. - Determining the optimum dyne level for a process.
Most processes requiring good adhesion need a surface energy of at least 40dynes/cm. Sometimes higher is needed, and there can even be too high a level due to over treatment. Determining your process works best between X and Y is a great quality tool.
Most polymers have a surface energy between 30 dynes and 40 dynes when manufactured, common materials such as Polypropylene and Polyethylene are around 30dynes/cm, whereas materials with more complex chemistry, such as Nylon and Polycarbonate can be higher than 40dynes/cm. Oily materials, or contaminated metals, glass and ceramics can be lower than 30dynes/cm, whereas once they’re cleaned, they can be very high – sometimes even in the 100s.
So Which Values Do You Need?
It’s worth pointing out that while some materials are less than 30 dynes, the chemicals used to measure this low are usually dangerous and knowing your material is 20 dynes isn’t likely to help any more than knowing it’s less than 30 dynes. There are options if you want to go lower than 30, speak with us if that’s the case.
- Testing base materials: Usually, as most materials start around the 30dyne/cm to 40dyne/cm, this is a good place to start. If you’re reading lower than this, there’s likely a problem, and if it’s higher than this, it’s likely a good thing. Typically 30, 34, 38 and 42 are used for this type of testing.
- Testing a process such as cleaning, plasma or corona treatment: Performance for adhesion often starts around the 40dynes/cm mark, but can go up to 72dynes/cm when measured with test inks, so a broader range is recommended and missing the lower values. Typically 40, 46, 52, 58, 64 and 70.
- Determining the optimum dyne level for a process: Knowing where your material starts and where it ends after treatment or processing requires the widest range so taking as many as you sensibly can is recommended. Typically 30, 38, 46, 54, 62, 70.
How Close Together Should Values Be?
Most people won’t see much, if any difference between one or two dynes – 33 to 34 will show next to no difference. Even going up in twos can be difficult to see.
It is often recommended to go up in fours, although 6s and 8s can be sensible because there will be a very defined pass/ fail to even untrained users, so anyone can easily and quickly take a reading. This obviously comes at a loss of definition, but it is rare to find a problem where only a dyne or two will make a big impact on performance.
Type A, Type B, Safety and ISO 8296
To add to the decision, there are also different types of ink. Type A is classed as Toxic, but conforms to the ISO8296 global standard which is the main one for manufacturing and testing of this type.
Type B is non-toxic but is a more generic formula made by us here at the Ebble Group.
Our usual recommendation is that if you want to measure in factories across different countries and buy locally, then Type A is definitely the way to go and just ensure you use the correct PPE and observe safety information.
If you are implementing a local quality test then Type B is often very sensible.
If you have a quality process imposed by a customer or supplier, you should check their type as results can vary between the different versions due to the chemistry and compatibility with materials.
Other Surface Energy Test Methods
Measuring surface energy using test pens and test inks is often the most common method due to cost and ease of use, but there are a couple of other methods that are more technical.
Contact Angle
Contact angle uses a pure liquid with known properties and looks at how it interacts with the surface. This method is very accurate and can give more information on the material surface than the pens alone. These systems are quite a bit more expensive and are fragile in comparison to pens and inks, also needing a higher trained operator but the results they give are very useful.
Contact angle is likely a tool found in a a quality lab, or a high end manufacturing line due to the fact that the systems gather more information and can store images and information for quality control.
Force Tensiometers
Force tensiometry is a versatile and accurate method of measuring surface energy similar to contact angle. These systems are especially good at measuring materials not commonly measured by the other methods; materials such as powders and filaments for example.
They work by dipping a solid material in to a liquid and using a microbalance the interaction between the two can be measured. This very accurate method is brilliant for labs but needs a stable surface and isn’t very portable. The operator training requirement is high and costs can be higher than contact angle systems but in many cases, their results cannot be obtained in any other way.
Still Don’t Know What Dyne Inks to Get?
Speak with us and tell us what you want to do, we’re happy to share our experience in measuring and typical values.
We offer a free of a charge testing service for samples too so we can figure out exactly what you need and can also offer lab support where we can use the different types and compare these results with contact angle readings.
You can buy online, book in a free of charge test session or get in touch to discuss more before making a decision.
