Saturday, June 20th marked the first official day of summer. For those of us in the Northern part of the United States, we’re quickly feeling those warmer temperatures rise! There are rumblings of summer sports coming back, cookouts taking place, and beaches starting to reopen. Ah, sweet sweet summertime.
So, you’re probably wondering what the heck does this have to do with adhesives? Great question. Not many people think about adhesives on a daily basis, but self-proclaimed glue nerds like myself think about glue all the time. Okay yes, maybe that sounds a bit weird, but SOMEBODY needs to think of this stuff! So, let’s take a trip into my mind (if you dare), and talk about the change of seasons and how that affects hot melts and water-based adhesive performance.
Hot melt adhesives
Let’s start with the easier one – hot melt adhesives. These products are very resilient. Because they are heated, they create their own “atmosphere” and therefore environmental conditions play less of a roll in performance. However, moisture can be a real problem. It can decrease performance and may result in the hot melt boiling out and creating a mess. If room temperature hot melt is not protected by a moisture barrier in the container, moisture can form on the glue and you’ll have the same boiling, foaming situation. This doesn’t happen often, but can in extremely high humidity situations. Hot rainy days or poorly stored hot melt are the usual culprits.
Water-based products
Now, let’s talk about water-based products. These products are much more susceptible to heat, cold, and humidity changes. In the winter months, production facilities are typically pretty cold and the building heaters make the air very dry. These conditions directly affect the performance of water-based adhesives. Adhesives stored in a “chilly” plant become cold themselves, and typically, the colder the adhesive is, the longer it will take to tack up and hold the substrates together. This may not be a problem for laminations that are stacked and held for an extended period, but for a high-speed glue lap application such as box manufacturing or paper tube winding, cold glue with cold paper substrates can slow production down substantially. Not good!
Additionally, reduced moisture can allow the adhesive being applied to “dive” into the substrate leaving a starved adhesive joint. Adding more adhesive will usually just compound the problem because you have added more water. Therefore, if you are looking for your substrates to not warp or tunnel, extra adhesive is your enemy.
Furthermore, the adhesive may build-up on open pot machines. This may not cause a major problem, but it may make cleanup more difficult and time-consuming.
Does that mean in the summer the “living is easy” and my adhesives are safe?
Okay, your probably thinking – sounds like all the adhesive issues happen in the winter, good thing it’s summertime! No cold facilities. No cold substrates. No cold glue. Well, not so fast my future fellow glue nerd! There are still concerns – just different ones.
Unless you live in a tropical area, the high plant temperatures are less of a problem. The bigger issue in the summer months is that warm air holds more moisture than cold air. This may sound like a good thing as you won’t have dry substrates which is true, but now you have the potential to have the opposite problem. Cellulosic substrates will absorb moisture and the more they are exposed to high humidity, the more they will absorb. High substrate moisture is also a problem. Higher moisture slows down the adhesive and impedes the forming of wet tack which is necessary for fast production speeds.
My advice to you
- Keep substrate materials stored in cool to warm areas – not hot, not cold.
- If possible, cover substrate materials to control moisture.
- In the winter months, store adhesive and substrates in the warmest area possible until they are ready to be used.
- Consider the atmospheric conditions and adjust your expectations.
Follow these guidelines to keep your adhesives safe. And as always, HAR is here to help answer all your questions and concerns about the change of seasons and adhesive performance. Happy summertime!
Ken Schonauer
Manager of Technology and Compliance
Readers are invited to use the links below to find and contact a local adhesives representative that can help with your company's industrial adhesives needs: HAR Adhesive Technologies has a presence in seven distinct states, uniquely focused on serving the adhesives, adhesive application, and industrial glue equipment needs of each region in: Ohio, Indiana, Kentucky, Michigan, New York, Pennsylvania, West Virginia