A dyne test is a method of evaluating materials to ensure surfaces are prepared to support adhesion. Dyne tests measure force to determine the surface energy of a material, which helps us select the glue best suited to a specific substrate. This test is performed on substrates using dyne pens that contain an ink that beads to indicate the material’s level of surface energy. Glue must be able to wet the surface of a substrate or it will result in poor bonding. When glue is applied to a substrate, its degree of wetting, or wettability, is significantly impacted by its own surface energy and that of the substrate. For wetting to occur, the surface tension of the glue needs to be lower than the surface energy of the substrate. Measuring dyne levels helps identify problematic materials with very low surface tensions and apply an ideal fix.
We take great pride in our ability to provide free comprehensive adhesion testing for any application through our advanced lab capabilities. Located on-site at the main LD Davis manufacturing facility in North Carolina, our full-service research and development lab leverages the technical skill of our experts to create solutions that enhance product performance for customers. We’re dedicated to providing the highest quality products and technical service, which is why and how LD Davis continually develops high-performance applications for glue and gelatin.
Glue-up tests are procedures that reveal the bonding capability of glues to substrates and help determine the setting speed of materials. This test is performed by cutting each substrate into small sections to apply glue to perform drawdowns. A drawdown board and Mayer rod are used to ensure an even glue application, and a four-inch speedball roller is pressed onto the surface with medium pressure. After standing at room temperature for 24 hours, the bonds are tested by pulling the substrates apart and evaluating the condition of the materials. A successful bond occurs when failure in the form of a fiber tear is apparent on one of the substrates, which indicates a complete permanent mechanical bond has formed. If no fiber tear is detected, the substrates are said to be held together by a suction bond, which is a much weaker bond. Suction bonds are not permanent and are likely to negatively affect product performance.
Heat and humidity tests are conducted to help measure the amount of curl between the glue and a substrate or determine how well a bond will hold under extreme conditions. After substrates have bonded together, they are placed in a humidity chamber at the desired temperature and humidity. Typical testing temperatures range from room temperature to 120°F, but can be higher depending on the glue, and humidity can reach 100% if need be. A typical time frame for testing is 24 hours. The substrates are then removed from the chamber and the bond is immediately evaluated.
A force test is used to determine the amount of force needed to separate bonded substrates once they have been glued together. Tests are measured in pound-forces or newtons by attaching a spring scale to one of the substrates and slowly applying a pulling force until the two surfaces separate.
A freezer test is used to determine how well a bond will hold up under freezing temperatures. This is an especially important test for determining the most effective adhesive for food packages that will be stored in the freezer. Samples are placed in our freezer at the desired freezing temperature for a set amount of time. Temperatures can reach as low as -40°F. The samples are then removed, and the bond is immediately tested for flexibility, strength and other important properties.
“LD Davis Industries has been a valuable supplier of hot melt to our company for over 15 years. In our foam fabrication business, controlling overhead drives the bottom line. Many of our competitors have moved away from adhesive bonding to go to zero-cost heat bonding for some of our foam substrates. Our years of experience have shown that the hot melt supplied by LD Davis allows us the flexibility and versatility to provide durable, unique solutions to our customer’s needs. Tripp Davis and his team at LD Davis are well aware of the constant overhead and pricing pressures we face, and constantly work to find us the price-to-performance products that our ever-changing business require. Great product only gets you so far if you can’t get it. LD Davis’s ability to handle all aspects of the supply chain-manufacturing, warehousing, and just-in-time delivery gives our company a competitive advantage in our market that we need.”
“Unipak and LD Davis have been working together for decades, so when we purchased our first Emmeci back in 2000 we asked them to provide the glue for these state of the art machines. Sixteen years later, we are still using glue provided by LD Davis on our Emmeci’s and couldn’t be happier with the product and the company behind the product. We have relied on their technical support to help us bond specialty papers and board and are extremely happy with the everyday performance of their NW123CK glue. Unipak is proud to be a part of LD Davis’s 90 year history and look forward to our continued relationship.”