All materials have a surface energy; dyne inks measure the surface energy of a material to determine its ability to interact with the rest of the world.
Deciding which dyne 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 as high as 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.
Which values do you need?
- 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 sixes and eights 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 few dynes will make a big impact on performance.
Type A, Type B, Safety and ISO8296
To add to the decision, there are also different types, such as A and B. Type A is classed as toxic, but conforms to the ISO8296 standard, which is the main one for testing of this type. Type B is non-toxic but is usually a little harder to read and is not suitable for polypropylene (PP). Using small amounts with the correct PPE normally negates the toxic issues and allows Type A to be the preferred ink of choice.
Pens and Bottled Inks
The final decision is inks vs pens. 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 pen 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.
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.
In terms of Tantec’s supply, both inks and pens contain the same liquids, and their cost per ml is the same, however, pens are 15ml and bottles are 30ml, so inks do cost more over the same range.