Running into issues getting an accurate glue viscosity reading from your equipment? We have good news. There are tools on the market that can help you measure viscosity. One of them is called a Zahn cup.
What is A Zahn Cup?
A Zahn cup is a viscosity measurement tool that provides a viscosity reading in centistokes. It is, most commonly, a stainless steel cup with a tiny hole in the center of the bottom. The cup is attached, on both sides, to a long handle.
There are five cup specifications, labeled Zahn cup #x, where x is the number from one through five. Large number cup sizes are used when viscosity is high, while low number cup sizes are used when viscosity is low. (Wikipedia)
How to Use a Zahn Cup
Using the Zahn cup to measure viscosity is pretty straightforward. The tools you will need to get your measurement are: a Zahn cup, a timer or stop watch, and a pen and paper.
Here is how to use the Gardco EZ Zahn cup to measure viscosity of our glues:
1. Select the proper Zahn cup size (based on the expected viscosity range). The cup commonly used with our protein glue is cup #3. The cup used could vary.
2. Clean any residue from inside of the cup before use. The cup should be competely dry before use.
3. Make sure the glue being tested is at (or close to) the recommended operational temperature. For protein glues, this is typically between 140-150° F (60-66° C). Measure and record the temperature when the test begins.
4. Completely immerse the cup into the glue. Keep the cup in the glue for a few seconds to ensure no bubbles are in the cup.
5. Hold the cup vertically using the handle. In a quick steady motion, lift the cup out of the glue, starting the timer when the top edge of the cup breaks the glue surface. During the flow time, hold the cup no more than 6” above the level of the glue surface.
6. Stop the timer as soon as you see the first break in the stream of glue at the base of the cup.
7. Record the number of seconds it took for the glue stream to break (efflux time), the glue temperature and the cup number. (ex. 16.4 seconds, 64°C, No.3 cup). You can then refer to the conversion table for the appropriate cup size which is provided with the cup. This will determine the centistoke viscosity for the values you recorded.
A "good" efflux time for most protein glues is 16-20.9 seconds.
Each glue formula has a different viscosity "sweet spot". If you're unsure of the proper viscosity for your glue, feel free to email our technical team about your specific product.
Once the viscosity is where you want it, you are ready to run your glue!