ACCU DYNE TEST™ Marker Pens

• Data

  Standard Dyne Levels Include:	30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70 and 72 dynes/cm.
  Non-Standard Levels Include:	31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67 and 69 dynes/cm.

Dyne solutions may work well in the lab, but in the shop a more robust device is indicated. This suggests "dyne pens" for online testing. Several types are readily available.

Most rudimentary is a nominal go/no go tester: Above a certain treatment, this pen marks the surface; below this level, the ink disappears. These pens identify and permanently mark the treated side of PE and PP films - aside from this, they have little use, since their initial accuracy is undocumentable and their design is subject to contamination.

A second style is formulated at several dyne levels, enabling the user to test over a range of treatments. Generally, these markers are interpreted based on which dyne level takes closest to two seconds to form beads (similar to the standard ASTM and TAPPI methods). These test markers are easy to use and, when first used, often quite accurate.

Unfortunately, their "Magic Marker" style nibs serve as perfect conduits for contamination of almost any kind, including machine oils, airborn lubricants, plasticizers, slip additives, etc. The very wicking qualities which facilitate their use make them self-contaminating as well. This dynamic interaction between the instrument and the substrate essentially eliminates such wicking style applicators for serious dyne testing.

Thus, the ACCU DYNE TEST™ Marker Pen, which is based on a valve tip applicator. The principle is simple: Keep the testing part of the pen away from the fluid storage part of the pen (in other words, no wicking from the substrate).  By pressing the tip firmly down, the valve is opened and fresh fluid floods the tip; this flushes it clean, and allows the tester to lightly pass over the sample to accurately determine dyne level. Results are based on how long the test solution takes to form beads on the sample surface.

This is a relatively accurate surface energy measurement technique; used in standard 2 dyne/cm increments, ACCU DYNE TEST™ marker pens can generally produce results with a precision of /- 2.0 dynes/cm. Repeated use of ACCU DYNE TEST™ marker pens should enable testers to estimate surface energy to within /- 1.0 dyne/cm.

To investigate discrepancies between obtained and expected results, a more precise measurement method should be considered; application of ACCU DYNE TEST™ surface tension test fluids with cotton swabs (per ASTM D2578-84) or by use of a drawdown rod is recommended. Alternatively, if results are suspect, replicate the test with a set of unused markers. This test has proven itself on a wide variety of substrates; it is, however, theoretically more prone to contamination than some other techniques. For this reason, even in the absence of unexpected results, you should establish a quality assurance plan which calls for regular audits during the phase-in stage of ACCU DYNE TEST™ marker pen use. The effect of all changeovers from one substrate to another should be monitored especially closely. Slip and other additives tend to bloom to the surface of extruded sheets and films; transferring surface-active additives from one material to another can have a profound effect on surface energy measurement. In general, once you demonstrate that a switch from substrate A to substrate B has no effect, it is safe to assume that future changeovers from A to B will act similarly. Thus, the frequency of backup audits decreases over time.

Finally, a few qualifying words. Surface energy is critically important to many converting operations. Unfortunately, it is not the sole determinant of product suitability. Other factors, such as surface topography, coating rheology, and chemical incompatibility, must also be considered. This is why broad-based communications with vendors and customers is so important. But at least by systematically measuring substrate surface energy, you will have a sound starting point from which to resolve other problems which may arise.