1. Does surface roughness affect the measurement? Can you measure on curved parts? Because the Surface Analyst uses patented Ballistic Deposition to deposit liquid drops, the user can easily take measurements on surfaces with varied shapes, orientation, and texture. While Ballistic Deposition minimizes roughness effects, if the roughness varies greatly from point to point, there can be a small effect on the contact angle.
2. Does measuring vertically impact the measurement? No. Because the Surface Analyst uses very small liquid drops, surface tension forces on the drop are much greater than gravitational forces. Therefore, orientation of the surface does not effect measurement: vertical, inverted, inclined surfaces all return the same value of contact angle.
3. How does it compare to a benchtop system? Unlike a benchtop goniometer, the Surface Analyst is portable and handheld, and removes subjectivity on the part of the operator in taking a measurement. It is designed to work on the surfaces of manufactured parts: injection molded, machined, sanded, blasted, painted, etc. where a benchtop goniometer is limited when it comes to measurements on parts with contours, shapes, and surface roughness. The precision of the contact angle calculation is equal to or better than a benchtop system.
4. What is the output of the system? What is it actually measuring? The Surface Analyst measures the contact angle of water, which is primarily sensitive to the polar component of the total surface energy. With a simple calibration curve, the water contact angle can be precisely correlated to the total surface energy. The surface energy of a material directly relates to cleanliness and to the potential to form a strong bond with an adhesive or coating.
5. What is the repeatability? The Surface Analyst has a repeatability better than 1° on well-prepared surfaces.
6. Why use only one liquid? We use non-destructive, highly purified HPLC water which does not harm the surface. Water, as a highly polar molecule, is very sensitive to the polar component of surface energy. This is a non-destructive test which is important when measuring production parts. We use this method because our research and others have shown that the non-polar or dispersive component of surface energy remains almost constant with surface treatments and doesn't correlate with properties like adhesion. Surface treatment and surface engineering processes only affected the polar component.
7. Does temperature or humidity affect the measurement? Humidity does not affect the measurement as long as moisture is not condensing on the surface to form visible droplets. Temperature can have a small effect that varies with the surface measured. The effect should be evaluated on the surface of interest if measurements are taken over a wide temperature range.
9. How do you calibrate the Surface Analyst? Factory calibration includes confirmation of drop volume and comparison of the calculated contact angles with those measured using a NIST-traceable NRL-type goniometer.
10. How do you export the data? The Surface Analyst stores all the data. This includes the measurement, time and date, user, and image. Furthermore, the software, Archer, provides a routine for exporting contact angle data and images onto a desktop or laptop computer. The data is then exported in an Excel file, images folder, and/or HTML format for easy viewing for analysis. Data is exported via provided USB stick or by directly connecting to PC.
11. Can the Surface Analyst small parts? The Surface Analyst is uniquely suited to measure small parts. The smallest part to date is a french gauge of 4, 1.3 mm inch diameter, catheters for medical devices.