In our last blog entry we introduced the low volume viscosity measuring kit, a customization option and consumable set that makes it possible to measure the viscosity of samples as low as 90μL in volume, one example of how Kyoto Electronics Manufacturing is helping users prevent the undue waste of expensive, precious samples.
This time we will be testing the ability of the EMS Viscometer's low-viscosity measurement probe to measure ink, a product that is the subject of many of the EMS-related inquiries that we receive. Unsurprisingly, viscosity is one of the most important physical properties that dictate ink's ability to perform as intended by affecting things such as its ability to, and speed of drying on various substrates, and how it stands up to physical stresses of certain applications.
So now with that little bit of background explained, let's go ahead and talk more about the tests and the results!
Aims:
1. To achieve the stable and reliable viscosity measurement of 4 different inks,
using the low-viscosity and standard probes.
2. To note the repeatability of results gained using the low-viscosity and standard probes.
3. To determine if there are any discernible differences in viscosity between the different inks.
Sample, Instrument Settings, and Testing Conditions
Samples*: inkjet printer inks (black and magenta),
highlighter inks (yellow and pink)
Sample size: 300 μL
Probes: φ1.5 mm aluminium alloy (low-viscosity probe)
φ2 mm aluminium (standard)
Motor Rotation Speed: 800 rpm
Sample temperature: 20°C
Measurement time: 1 second per measurement
Number of measurements: 100 (performed consecutively in 1-second intervals)
Wait time: 5 minutes
*samples were standard store-bought inks
Measurement Results
MAGENTA INKJET INK | φ2mm aluminium (standard) | φ1.5mm aluminium alloy (low viscosity probe) |
Average Viscosity | 2.210 mPa・s | 2.246 mPa・s |
Standard Deviation | 0.00528 | 0.00195 |
Relative Standard Deviation | 0.24% | 0.09% |
BLACK INKJET INK | φ2mm aluminium (standard) | φ1.5mm aluminium alloy (low viscosity probe) |
Average Viscosity | 2.455 mPa・s | 2.512 mPa・s |
Standard Deviation | 0.004433 | 0.00178 |
Relative Standard Deviation | 0.17% | 0.07% |
YELLOW HIGHLIGHTER INK | φ2mm aluminium (standard) | φ1.5mm aluminium alloy (low viscosity probe) |
Average Viscosity | 6.263 mPa・s | 6.273 mPa・s |
Standard Deviation | 0.1580 | 0.0194 |
Relative Standard Deviation | 2.53% | 0.31% |
PINK HIGHLIGHTER INK | φ2mm aluminium (standard) | φ1.5mm aluminium alloy (low viscosity probe) |
Average Viscosity | 3.544 mPa・s | 3.309 mPa・s |
Standard Deviation | 0.0269 | 0.0108 |
Relative Standard Deviation | 0.76% | 0.33% |
*For reference １mPa・s is equivalent to 1 cP
Discussion
Average viscosity values differed slightly between the 2 probe types for all inks assayed, with the biggest difference being observed for pink highlighter ink. Repeatability was great all around, but especially so for the low-viscosity probe (RSDs of 0.09%, 0.07%, 0.31%, and 0.33%!), a result that was hypothesised and nicely proven by the data. Interestingly, repeatability was best for both probe types when measuring the magenta and black inkjet printer inks. We noted that viscosity was slightly higher in the highlighter pen inks than the inkjet printer inks with the most viscous being the yellow highlighter ink.
In addition to the joy of getting accurate, consistent results, it was lovely to not have to clean ink from the instrument each time, thanks to the sample tube measurement system employed by the EMS-1000S. Measurement simply required setting the next tube and pressing start; how easy! This experiment required that each sample's temperature be at room temperature (20°C) which was facilitated by the in-built heating function (working range of 0-200°C). For peace of mind, you may assign a "Hold Time", which instructs the instrument to wait an assigned time after reaching the desired sample measurement temperature to ensure this temperature is stable before starting measurement. For samples coming from, and to be measured at room temperature (20°C), this hold time needn't be very long (a minute or two should suffice), though we opted to set it to a leisurely 5 minutes on this occasion to suit our schedule.
Though 8 samples (4 inks x 2 probes) were measured 100 times each, the whole experiment was able to be performed in under a mere 2 hours, with each sample requiring only 8 minutes in the instrument (hold time of 5 minutes + 3 minutes for 100 measurements = 8 minutes)! Even counting for sample tube changing, the whole process required less than 2 hours. So speedy! What's more, measurement can be left unattended once initiated, freeing up time to perform other tasks (such as sample preparation and data analysis).
If you are looking for easy and hassle-free viscosity measurement, consider giving the EMS-1000S a spin! Developed especially to measure the low range, the φ1.5mm aluminium alloy probe is perfect for measuring low-viscosity samples such as ink and blood. Its ideal measurement range is 0.1~1000mPa･s/cP, so it is perfect for ink.
We hope that you enjoyed the article!
If you would like to learn even more about the scientific background of the EMS technology, please check out the measurement principle found here.
For those with questions such as "Can my sample's viscosity even be measured?" and "Which probe should I choose for my samples?", please make sure to contact us by clicking the yellow “contact” button at the top of the page. We and our distributing partners are standing by to help you with technical inquiries and to arrange a demo to test your samples.
Thank you for reading!