One of the questions Bond Products’ customers ask us about is how to fix a dripping glue gun tip. We sell a number of different glue guns, glue sticks and slugs, and other glue gun supplies, and we always want to make sure our customers are satisfied with their products. So here is an explanation of why dripping often occurs and what you can do about it.
Why Is Your Glue Gun Tip Dripping?
There are a number of factors involved in how well a glue gun operates. It’s a combination of the glue formulation, its viscosity, the diameter of the sticks by manufacturing being maintained inside the specification of the glue gun design, and, perhaps most importantly, the ongoing maintenance of the glue gun by the user.
When you heat your glue gun up from a cold start, you will likely see some dripping at first. Most glue guns drip when they first heat up. This is due to the expansion of the glue as it transitions from a solid to a liquid.
Most of the 12mm (1/2”) or 15mm (5/8”) glue guns have an extension nozzle design. This means that the extension tube of the nozzle which has glue inside is past the check valve. With extension nozzles those glue guns will also have a few drips throughout the day. Basically, every time the glue gun is used, a small amount of adhesive will melt past the check valve, and gravity will pull on it and cause it to drip. However, if a glue gun is dripping constantly, this is usually a sign to replace the nozzle or check the type of adhesive being used.
The Type of Glue Matters
Some glues are of a polyamide formulation which is moisture sensitive. Polyamides will absorb moisture from the humidity in the environment. If you use this type of product and allow the sticks to be moisture contaminated, the glue gun tip will drip nonstop. The moisture that is trapped in the glue stick is boiling inside the glue gun’s heating chamber, and the pressure builds up. This pressure releases itself by opening the nozzle valve and dripping down from the nozzle tip.
Under normal circumstances because of the way glue guns are designed, the glue stick will “relax” when the trigger is released. Heat up your glue gun and feed a glue stick through. With the trigger compressed, mark the glue stick with a pen at the back of the inlet tube just before the glue stick enters the melt chamber, then wait a few minutes. You will see the glue stick will move backwards up to a half an inch or so. This is the result of the material in the heater housing melting and expanding. As that happens, the pressure that is created in the heater housing by the thermal expansion pushes the glue stick back.
However, if a glue gun has what’s called “melt back,” which can occur from laying the glue gun on its side, this can act as a resistance to this relaxing effect. It will cause the glue gun to drip as the pressure opens the nozzle valve.
Sometimes fibers or other debris works its way into a glue gun over time. This debris can build in the nozzle and cause the valve to be unable to close. The fix for this is to remove the nozzle while the tool is hot, purge a half stick or so through the tool, and install a new nozzle. Nozzles do wear over time, so changing out the nozzle is often the easiest solution to fixing a dripping glue gun. Bond Products has long nozzle glue gun tips available for sale.
This may be a longer explanation than you were expecting for why a glue gun tip drips and how to fix it, but this problem can have a number of causes. If you know why dripping may occur over the life expectancy of the glue gun, it’s easier to know what to do. If you need help with finding supplies for your glue gun, call us at 1-888-800-BOND. We will be happy to help.