Hot-melt adhesive

3M Scotch-Weld Hot Melt Applicator The Hot melt adhesive (HMA), also known as hot glue, is a form of thermoplastic adhesive that is commonly supplied in solid cylindrical sticks of various diameters, designed to be melted in an electric hot glue gun. The gun uses a continuous-duty heating element to melt the plastic glue, which may be pushed through the gun by a mechanical trigger mechanism, or directly by the user. The glue squeezed out of the heated nozzle is initially hot enough to burn and even blister skin. The glue is tacky when hot, and solidifies in a few seconds to one minute. Hot melt adhesives can also be applied by dipping or spraying.

In industrial use, hot melt adhesives provide several advantages over solvent-based adhesives. Volatile organic compounds are reduced or eliminated, and the drying or curing step is eliminated. Hot melt adhesives have long shelf life and usually can be disposed of without special precautions. Some of the disadvantages involve thermal load of the substrate, limiting use to substrates not sensitive to higher temperatures, and loss of bond strength at higher temperatures, up to complete melting of the adhesive. This can be reduced by using a reactive adhesive that after solidifying undergoes further curing e.g., by moisture (e.g., reactive urethanes and silicones), or is cured by ultraviolet radiation. Some HMAs may not be resistant to chemical attacks and weathering. HMAs do not lose thickness during solidifying; solvent-based adhesives may lose up to 50-70% of layer thickness during drying.^[1]

Hot Glue Gun Tips

Today, there are lots of different sizes and both low and high temp options, so choose based on what you will be crafting.  Unless you are working with teensy tiny crafts, I would recommend starting with a medium sized gun like&nbsp. (This particular gun is also a dual temperature gun and it is almost half off to boot!)   When shopping for hot glue sticks, make sure you are getting either high, low or dual temp sticks based on the type of glue gun you have, and be sure to get the right size!  Those miniature glue guns will not work with standard sized glue sticks and vice versa.

Before we get started with the nitty gritty, let’s talk about WHY hot glue is fabulous, shall we?  First of all, it can attach almost anything to almost anything else.  Wood to metal to paper to cork.  Brilliant.

Hot glue is also magical in that it causes less damage than your average adhesive.  In college, we used to attach photos and such to our cement block walls with hot glue because you could simply pull the whole thing off, hot glue and all, at the end of the year.  Of course, hot glue won’t come off paper or drywall as easily, but you get my point, right?  That same quality applies to those little “accidents” — the strings of glue that hang off your projects and the “overflow” that sometimes occurs when you use too much?  Those are easy to pull off and away when dry, making projects look seamless.

Just remember…

NEVER touch hot glue when it is HOT!  Just don’t!

Moving on, I am going to take you through a couple projects that show off the basics of the hot glue gun.  First off? Easter Egg Checkers.  I had to attach the little wooden eggs to the bottlecaps with hot glue, making sure they were attached perfectly straight up and down before the glue dried.

See that long string of glue hanging from the tip of the gun?

Beginner’s Tip:  DO NOT hold the glue gun super far away from the object you are gluing.

Those strings are easy to remove, but why make more mess than you need to?

Lay off the trigger,  pull the tip sideways just a bit to “cap” the glue and pull away.

Beginner’s Tip:  Let the glue gun warm up fully before attempting to use it.  The hotter the glue is, the better the glue will work!

Beginner’s Tip:  Make sure you allow the glue to dry fully before moving the project.  Hot glue dries quickly, but not THAT quickly.  You don’t want an ooey, gooey mess on your hands! (see below)

https://youtu.be/RAybbxd3jYs

 

What Are Hot Glue Guns?

Hot glue guns are portable devices that utilize and dispense hot melt adhesives . First produced in the 1940s, hot melts—thermoplastics in the shape of tubular sticks—were created as an improvement to water-based adhesives that weaken when exposed to humidity. When they were initially fabricated, hot glue guns were used to bond shoe soles, though they are applicable to various other projects and materials. They are used to apply glue to delicate cloth fabrics and to denser materials, including wood.


3M Scotch-Weld Hot Melt Applicator TC with Quadrack Converter and Palm Trigger

Common Glue Gun Applications

• Woodworking  
• Retail Manufacturing
• Recreational Decor
• Shipment & Packaging
  

Glue Gun Operation

Hot Melts

To ensure the best bonding results, a compatible hot melt adhesive is essential for each glue gun and application. Hot melts vary in width and length and are generally in the form of waxes, resins and a variation of thermoplastic polymers. The chemical composition of hot melts varies, because they may produce soft or hard glue product. They are manufactured in different colors to match specific job applications. Typically, hot melts are waterproof and able to withstand chemical treatments, but they are not suitable in high temperature applications.

Glue Gun Operation

During the process, the hot melt sticks are pushed through the back cavity of the device either manually or by pulling a trigger, depending on the model of the gun. Once activated, the glue is pushed to a check valve, which is a spring loaded with balls that are located directly behind the nozzle. The valves are designed to stop the flow of the glue and to prevent spills. Various glue gun models are equipped with a viewing window which allows the user to determine if an efficient amount of adhesive is in the chamber.

Generally, melting takes between two and five minutes, but the process may be shorter depending on whether the gun has been preheated or  is already in use. In standard glue guns, the temperature of the hot melts is controlled bythermistors, thermally sensitive resistors that limit the heat current during the melting process. Since they regulate heat, glue gun resistors allow operators to handle the device without getting burned.

Glue is dispensed from a conical nozzle, which is typically metal and may become extremely hot. Various manufacturers fabricate glue guns that feature nozzles with a protective rubber encasing, to prevent burns. The glue can be dispensed in thin strips, and once expelled from the gun, glue generally takes only a few minutes to dry and harden.  

Additional Information & Considerations   

Experts and manufacturers advise some guidelines to ensure an effective process:

Heat proof counters or trays are essential during the glue gun operation, as hot melt adhesives may drip if too much force is applied to the glue.

Temperature is a major factor in the post glue gun application process. Glue that is exposed to too much light or heat will melt, whereas glue that is exposed to cold temperatures will become brittle.

Selecting the right type of gun model is essential for every application: Low temperature guns melt glue at 250 degrees and are suitable for delicate materials. High temperature guns can reach 400 degrees and are only compatible for more durable or “hard” materials. Manufacturers produce dual temperature models for multiple projects.