You're running animal glue on your production line and all of a sudden, it doesn't seem to be working properly. Your wraps aren't sticking and the glue seems to be drying too quickly. What happened?
First things first, don't panic. Issues like this typically have a very simple solution.
When your glue doesn't seem to stick, it's because it is setting too quickly. What that means is that the glue is drying before a bond can be made. There are a few reasons this could be happening.
Possible Cause #1: Glue Temperature Is Too Low
We've discussed this before, but it's worth repeating: temperature is one of the most critical specifications when it comes to prepping your glue. Animal glues run best at a temperature between 140-150 degrees Fahrenheit. This optimal temperature may vary a few degrees depending on the conditions in your plant.
Is it extremely hot?
Is it freezing cold?
All of these details play a role in the glues performance. You may find a temperature "sweet spot" for your glue in the winter months, and it may be slightly different in summer months.
If your glue is drying too quickly, one of the first things you want to do to troubleshoot the issue is to slightly raise the glue temperature. This will help keep the glue tackier for a longer period of time.
Possible Cause #2: Very Low Humidity
Like temperature, humidity will play a role in the tackiness of your glue. Low humidity in your plant could be causing your glue to set quicker than desired.
To troubleshoot the issue, humidify the surrounding area if possible. It may also help to dilute the glue to lower solids (you can measure solids in your glue with a refractometer) by adding hot water to your glue pot, or increase your glue application rate.
The "ideal" humidity in a manufacturing plant is 40-50%. This is not always easy to achieve if your plant is not climate controlled, but you can easily measure this with an inexpensive temperature and humidity gauge.
Possible Cause #3: Glue Application Amount is Too Low
This may seem pretty straightforward, but it could be a simple solution to the problem. If your glue is setting too quickly it may be because you are not applying enough glue to your substrates.
Most of our animal glues run best at 2 mils on the roller (you can measure this with a mil depth gauge). In some plant conditions, 3 mils may work better for you. This will all depend on the conditions in your facility.
Possible Cause #4: Solids Too High
If the solids in your glue are too high, this means that there is much more glue (solid) than water in the mixture. Water will actually allow the glue more time to stay "open", meaning that it will not dry as quickly.
To troubleshoot this issue, you will want to slowly add hot water to your glue pot. Make sure to measure the solids as you go until you have diluted to the recommended solids (this can be found on the Technical Data Sheet for your glue product).
Possible Cause #5: Substrates Not Stored Properly
Often times, we find that raw materials like board, and wraps are stored in a different area of the facility that is not climate controlled. You'll want to make sure that your substrates are not stored in an area that is too cold. We recommend wraps and boards be "staged" with the equipment for about 24 hours before running. Running glue on cold substrates could be a reason why you're experiencing bonding issues.
Make sure you are following best practices for storing and handling all raw materials.
Possible Cause #6: Machine Speed
Like we've mentioned before, not all glues are created equal.
Each formula is designed to be run at a certain temperature, viscosity, and speed. Machine speed will definitely come into play when it comes to the "open time" of your glue. If your glue is drying too quickly, this could mean that you need to increase the speed of your equipment.
As you can see, there are a few reasons that your glue could be drying quicker than you'd like. If these simple troubleshooting solutions don't help, our team is always happy to provide glue training or an on-site glue audit if that's possible.