Heat induction seal cap liners are a great way to keep products safe. They provide an airtight seal on a closure that helps prevent leaking or spilling and the introduction of contaminants. A good seal can also preserve product freshness. Pres-On offers several different types of heat induction seals, but the most popular are foil one-piece foam backed seals, pulp board and foil two-piece seals, and Lift ‘n’ Peel™ heat induction seals.
However, attaining a proper seal can sometimes be a challenge if you’re unfamiliar with heat induction. First, guarantee the cap, cap liner, bottle, and product are compatible. The experts at Pres-On can help with this step. Please contact us if you need any help with finding a compatible cap liner. More importantly, to ensure a proper seal the right amount of heat, pressure, and time must be applied. So where do you start?
Heat induction sealing is the process of applying heat from an induction sealer to a foil liner inside the cap of a container. It is a non-contact process. The induction sealing machine generates an electromagnetic field that causes the metal particles in the liner to heat up. This heat melts the polymer coating on the cap liner. The melted polymer creates hermetic seal that is tamper-evident and helps protect the product from contamination and leakage.
Other heat sources will NOT work. You need a heat induction machine. DO NOT use a hair dryer, an iron, an oven, or another unapproved source of heat. ONLY the electromagnetic field from a heat induction machine will provide a proper seal for a closure.
As stated before, to attain a proper seal the right amount of heat, pressure, and time must be applied. Although heat and time are important, the first step is applying pressure. An adequate amount of downward pressure on a cap liner can be achieved by finding a cap that properly fits its closure. However, even if the cap fits properly there may be issues. Sometimes child resistant caps or other caps designed to have space between the top of the cap and the induction liner will not seal properly. Please contact your heat induction machine provider for assistant if you are having difficulties sealing a closure with a child resistant cap.
There is no straight answer when trying to find the best amount of heat and time to seal your liner. There will be a lot of trial and error. Some heat induction machine manufacturers recommend that you start by applying 50% power for a second or two.
If there is a partial or weak seal, there could be a couple causes. Verify that the cap is securely on and that there is uniform pressure on the liner. If the cap was properly applied, then try the next container at 5% more power. Continue this until you hit the goldilocks zone where the seal is perfect.
If you apply too much heat, then the seal will be overheated. An overheated seal will have excessive wrinkles, an unpleasant odor, pulp board discoloration, or foam deformation. For the next container, reduce power of the induction machine by 5% or for less time. After a couple attempts, you’ll be able to find the perfect settings for your heat induction machine.
Induction sealing is a great way to keep products safe, prevent leaking, and preserve freshness. Pres-On offers several different types of heat induction seals, but the most popular are foil one-piece foam backed seals, pulp board and foil two-piece seals, and Lift ‘n’ Peel™ heat induction seals. You need to properly use a heat induction machine for the sealing process to be effective. When operating a heat induction machine heat, pressure, and time are the most important factors. If you are still having trouble with getting a proper seal on your heat induction cap liners, please contact us, your cap supplier, or your heat induction machine provider.