Whether you’re involved in industrial manufacturing or are embarking on a woodworking DIY masterpiece, you’ll no doubt have to glue stuff together at some point on the job. Whatever the task you face, determining which adhesive is most appropriate for the job will be vital to your project’s success. As we say here at Hotmelt.com, not all adhesives are created equal, and we’re here to help you find the right one for any task.
Avoiding the Wrong Adhesive: Why it Matters
Ensuring that you use the proper adhesive for your unique application can make or break the success of your project. You always want to ensure you’re selecting an adhesive that will create a high-strength, long-term bond in order to reduce costs associate with re-adhering and repairs over time. When surfaces don’t stick together under the normal conditions, the consequences could range from the risk of customer dissatisfaction to violating product safety regulations.
Adhesives come in many unique styles, and not all adhesives are designed to stick to all materials. There are pros and cons to each type of adhesive, so it’s important to thoroughly assess your needs before looking for a solution. Ensure that you consider all factors, such as the materials you need to bond, environmental considerations and the flexibility required.
An Adhesive That (Seriously) Sticks: Types of Adhesives
Water-based adhesives are usually made from either natural polymers, such as starches, animal hides and dextrins or soluble synthetic polymers like polyvinyl alcohol, cellulose ethers and polyvinylpyrrolidone. These adhesives could come in the form of solutions or powders, which need to be mixed with water before application.
This adhesive becomes strong when the glue line loses water from absorption by the substrate or evaporation. As a result of this, these adhesives require that at least one of the substrates is permeable during application. Because the polymers are soluble in water, the bonds made from using these adhesives are not very resistant to water and moisture.
Assembly, packaging and paper converting applications, ideally with porous substrates. Non-porous substrates could also work in some situations, as well.
There are different types of acrylic adhesives: two-part acrylics and two-step acrylics. Two-part acrylics are popular for their strength, peel-resistance, durability and impact-resistance. They are ideal for tough environments, which are exposed to environmental elements like moisture and harsh weather.
Two-part acrylics are used a lot by the marine industry for fiber reinforced plastic (FRP) boat bonding, and also as an alternative to rivet placement and spot welding in panel bonding. These adhesives require mixing before application (usually a resin with an activator) and have a strong odor. As a result, they should only be used in environments that have good ventilation.
A two-step acrylic, on the other hand, requires no mixing, which gives it an edge over its counterpart. Like the two-part acrylic, these types of acrylics are also very durable, sturdy and ideal for demanding environments. However, two-step acrylics require an activator and aren’t great for gap filling. These adhesives are typically used in magnet bonding applications for speakers and electric motors.
Demanding environments, including magnet bonding applications for speakers and electric motors, boat bonding, rivet replacement, spot welding in panel bonding and more.
Epoxies are well-known in the industry for their resistance to heat and chemicals, electrical insulation properties and their high strength. They are very popular, particularly in the computer and electronic industries where they are used in the creation of circuit boards. Other industries like the aviation, automobile and marine industries also use epoxies to construct aircraft, cars, boats and any applications that require strong bonds.
These adhesives need to be mixed (through the combination of a hardener and resin), so they’re generally not considered as convenient as other types of adhesives. They are not recommended for plastic substrates or any applications that require flexibility.
Plastic substrates or any application requiring flexibility and a high level of resistance to heat and chemicals. Often used in computers and electronics to create circuit boards and to create aircraft, cars, boats and more.
These adhesives can be used in a wide variety of applications, including packaging, assembly and hygiene. They are very durable and provide superior flexibility when compared to waterborne or solvent-based adhesives. They are solvent-free and based on thermoplastic polymers.
At room temperature, they remain solid and can be activated when they are heated above their softening point. After they have been applied, they retain the ability to wet the substrate until they eventually solidify and return to a state that can function as an adhesive.
Hot melt adhesives include both natural and synthetic polymers. The melts typically have a high level of viscosity, and this makes them ideal for substrates that are permeable and porous or substrates that would otherwise have been more difficult to bond with solvent-based adhesives.
The packaging industry is a major user of hot melts, using these adhesives in applications that involve manufacturing packaging from cardboard, paper and corrugated boards. The printing industry is another major user of hot melt adhesives, as they are used for bonding book spines.
In the shoe making industry, they are used to bond shoe soles, and in wood processing, they are used for veneer surrounds and edging applications. These adhesives are tailored to meet specific application methods and demands, and they come in different forms, such has hot melt films, hot melt blocks and hot melt glue sticks for handheld glue guns.
Environments requiring superior flexibility and a high level of viscosity. Commonly used in packaging, assembly, hygiene, printing, bonding book spines, shoemaking and more.
These are not adhesives, however, they are important because they are portable tools that use and dispense hot melt adhesives. When they were first produced in the 1940s, hot melt sticks were created to improve upon the water-based adhesives that weren’t water/moisture resistant. They were manufactured as cylindrical sticks designed to melt in the glue guns before being dispensed. The glue guns are now used in various applications from delicate cloth fabrics to dense materials, like wood. Selecting the right glue gun is just as important as selecting the adhesive.
There are two main types of glue guns, depending on the type of application. The low-temperature glue guns melt glue at 250 degrees and are ideal for applications on delicate material, such as fabric. On the other hand, the high-temperature guns melt glue at up to 400 degrees and are only ideal for applications involving durable or hard materials such as wood. Some manufacturers such as Surebonder and Power Adhesives do produce dual temperature glue gun models.
Applications where you need to be able to dispense hot melt adhesives on the go. A good choice for adhering cloth, wood and more.
Super Glue (Cyanoacrylate Adhesives)
As one of the most commonly used products in both industrial or craft applications, super glue (also known as Cyanoacrylate) bonds very quickly and with a wide variety of substrates. These adhesives are waterproof, form a very strong bond and dry clear. The substrates to be bonded need to fit well together to achieve a good bond.
Super glue is also available in different levels of viscosities, so that users have a bit of freedom regarding gap-filling performance. However, they need to be applied very carefully, as that applying too little or too much could negatively affect the bond. Super glue is very cost-effective and works best in tensile applications that don’t have high-impact strength requirements. They are also great for projects that involve wood, ceramic, glass, leather, metal and sometimes plastic.
Craft and industrial applications where you need a strong, waterproof bond. A great choice for bonding wood, ceramic, glass, leather and some types of plastic.
These are single-component adhesives that are typically applied to the substrate in the form of a paste. The plastisol paste contains solid polyvinyl chloride (PVC) particles that are dispersed in plasticizer. Plastisols are known for being highly flexible and having good peel resistance. However, they are sensitive to stress and experience creep when subjected to heavy weights. In most applications, plastisols have no adverse effect when used as sealants.
As they are thermoplastics, their resistance to heat is limited. For example, during spot welding, there is the risk of releasing hydrochloric acid if plastisols are overheated. They are primarily used in vehicle body construction and help seal joints guard against moisture, in addition to their bonding function. PVC plastisols, however, are increasingly being replaced by adhesives like epoxy resins because of environmental issues when recycling bonded components.
Applications where you need high flexibility and peel-resistance. A good choice for applications like vehicle body construction.
Making the Right Decision
With all these brands and options, it can feel overwhelming to pick the right adhesive that fits your needs, but Hotmelt.com is always available to help guide you through the adhesive-selection process. One important way to ensure that you select the right one for the job is to conduct tests in order to ensure that you don’t get yourself into any sticky, irreversible messes. In fact, we always recommend testing your adhesives in a small, inconspicuous area to make sure that they perform to your standards.
Remember, you can always reach out to the Hotmelt.com team for one-on-one advice regarding which type of adhesive to use.