Many industries now rely on hot melt glue, rather than on silicone-based adhesives for bonding needs. Glue Dots® have become a simple, versatile and cost-effective way to complete tasks such as holding corner boards, adhering package labels and much more.
They are a great alternative to liquid glues, double-sided tapes or hot melts because they eliminate fumes, burns and long set-up times. These double-sided, pressure-sensitive adhesives bond instantly to almost any surface.
Glue spots come in a variety of profiles and tack types. The profile refers to the thickness and height of the glue. The tack level is merely the aggressiveness of the adhesive. Low tack is easily removable, medium tack is removable or permanent, and high tack is permanent.
Glue Dots®, a brand name, have exact equivalents, often called Adhesive Glue Spots. However, most people use either term, dots or spots, when describing this adhesive.
Prehistoric Man and Adhesives
Humanity has used adhesives for thousands of years. Humans have made glue from a variety of natural adhesives, including fish skins, sugar, animal parts and more. Most were made by boiling animal hides or hooves in water.
The Egyptians started using tar-based glue made from birch bark, precisely heated to a specific temperature. The process took time, and only the wealthiest used adhesives made from birch.
Glues were used for furniture and to help strengthen papyrus. The wooden furniture in Tutankhamun’s tomb was held together by this adhesive.
Cohesive Forces
Cohesive force is what makes molecules stick to other molecules. Without cohesive force, for example, raindrops would never appear on a window pane, as the drops would immediately slide off. Cohesive force holds the drops, at least temporarily until a stronger force, gravity, breaks the bond, to the glass.
This is because water molecules have positive and negative charges. Like a magnet, the positive sticks to the negative side and vice-versa.
Adhesive Force
Adhesive force is a bit of a mystery. Scientists cannot precisely explain what makes different adhesive substances create bonds between substrates.
Each different type of glue combines a distinct set of factors that create various levels of bonding.
Adhesives create a basic bond by a combination of different attractive forces, such as cohesion. However, stronger adhesives also bond chemically, creating a powerful attraction between the surfaces.
For example, some adhesive compounds have specific compounds that will bond chemically with plastic, establishing a secure connection between the plastic and the bond formed by the glue with another surface. Other adhesives bond chemically with different types of materials like wood or metal.
This process is called chemisorption.
Aside from the chemical processes, there are two theories as to why adhesives work as they do: The mechanical theory of adhesives and the diffusion theory.
Mechanical Theory
The mechanical theory posits that glues form mechanical bonds between surfaces. The argument is predicated on how all surfaces are somewhat porous, and the glue seeps through the holes and grips the material.
Diffusion Theory
The diffusion theory claims the glue molecules diffuse into the surface. The molecules of the glue mingle and join with the molecules of the substrate.
The difference between Glue Dots® and Infinity Bond Adhesive Glue Spots
Glue Dots® and Infinity Bond Adhesive Glue Spots come in identical tack and profiles. The roll layouts are also the same.
You can interchange or co-mingle the two brands. The main difference you will find between the two is the cost, as the Infinity brand is usually priced less for the equivalent amount and type.
Application of Glue Dots® and Infinity Glue Spots
Each type permits easy manual application. You can also purchase semi-automatic and fully automatic dispensing applicators that work with dots and spots.
The Advantages of Using Glue Dots® or Spots
Glue Dots® bond instantly. They also adhere to any surface, such as cardboard, paper, wood, aluminum, Styrofoam or plastic.
Depending on the type you choose, Glue Dots® are permanent or removable.
There is no liquid mess and no electricity, compressed air or heating involved unless you opt for a high-speed or assembly-line applicator.
Finally, you can buy FDA-compliant glue dot formulas which also conform to ASTM D-4236, concerning direct and indirect food contact. This makes adhesive dots an excellent choice for several uses in the food and beverage industry.
What Does ASTM D-4236 Mean?
ASTM (American Society for Testing Materials) International is the world’s leading authority on testing materials and making sure the materials are properly labeled in accordance with the Labeling Hazardous Materials Act (LHAMA).
The Act requires art materials, which is the category glue spots falls under for testing purposes, to have the appropriate warning labels. For example, you may have seen LHAMA labels, such as those reading “may cause skin irritation” or “harmful if swallowed.”
Glue spots are very safe to use, and they are non-toxic and odorless.
FDA Definition 21 CFR175.105 Adhesives: Indirect Food Contact
Glue Dots® are in full compliance with FDA regulations. Specifically, the chemical composition of Glue Dots® has no harmful health effects. The bond under normal conditions will be seamless, protecting the foodstuffs from contact with anything outside the container.
Glue Dots® Useful Shelf Life
When stored in the original packaging and a clean, dry and temperature-controlled environment, Glue Spots® have an extremely long shelf life.
High humidity, UV rays or a very elevated temperature can limit the shelf life and bonding quality.
Most companies recommend replacing adhesive spots in storage after 18 months.
Applying Glue Dots® and Adhesive Spots
You can apply Glue Dots® or adhesive spots manually or with one of the several types of application machines. Make sure the substrate is free of oil, dust and other contaminates, and then peel away the cover and press the adhesive onto whatever surface you want.
Machine Applicators
If you require assembly-line production speeds or some other repetitive glue dot application, there are several types of machine applicators on the market. Many do not require machine programming. You can load them with rolls of hundreds or thousands of adhesive spots, and the operator can advance the dot application as necessary.
The applicators, unlike hot melt applicators, do not require warm-up periods or any heat.
A bench top adhesive applicator machine permits perfect placement, on demand, with speeds at one per second, depending on the applicator.
Tack Level
Tack level refers to how aggressive the bond or level of adhesiveness might be. The tackiness is how well the glue dot sticks to the substrate.
There are four levels of tackiness: low, medium, high and super high.
The lower the tack, the easier it is to remove. Glues that are easy to remove, such as those found on the back of a new credit card, are sometimes called fugitive glue.
Each tack level contains a certain amount of oil to aid in its removal. Low tack contains the most oil, making it the easiest to remove.
Occasionally, you could have a slight discoloration when removing the dot due to absorption of the oil. This depends on the substrate. If you want the capability of removing the glue dot, test the substance first before determining the best tack for your needs.
Low Tack
Low tack provides excellent adhesion, but you can remove the dots that are bonding the substrate as required. Users most often use low tack for bonding lightweight material, like paper, together.
Medium Tack
Medium tack has slightly stronger bonding properties. Medium tack permanently bonds some materials together, but you can remove medium tack from certain other substrates.
Medium tack is the adhesive companies use to, for example, hold a credit card or other product in position when you ship it. You can remove medium tack, but it takes a little more effort than it does when removing low tack.
High Tack
High tack is considered permanent for most surfaces, but you can remove it with some effort. Along with medium tack, high tack works well if you must bond together circular or irregularly shaped materials.
Super High Tack
Super high tack creates a very stable bond. Removing super high tack adhesive spots is possible, but you may damage the substrates if you attempt to do so. Super high tack will tear paper and cardboard if you attempt to remove it.
Profile
A glue dot’s thickness is referred to as its profile. You can purchase adhesive dots of whatever tackiness you desire, then choose from three different thicknesses:
Low Profile
A low-profile glue dot is essentially flat at 15 mm or 1/64 of an inch thick. These dots are most commonly used when bonding between two very flat surfaces, such as paper.
Medium Profile
Medium profile dots are 55 mm or 1/16 of an inch thick. You might choose medium profile adhesive spots to bond Styrofoam to paper, for example.
High Profile
High profile is 100 mm or 3/32 of an inch thick. If you want to bond irregular or dissimilar materials, such as wood to wood, you may choose high profile dots.
Diameter
The standard diameter of all adhesive dots, no matter than tack or profile, is 1/2 inch.
Example: Low Profile, Super High Tack
The Infinity Bond GD XD41-404 Glue Spots form permanent adhesive bonds that are removable. These come in rolls of 4,000 dots in a cardboard release box.
Example: Medium Profile, Super High Tack
The Infinity Bond XD42-402 Glue Spots meet all the requirements expected in a medium profile dot. Perfect for Styrofoam bonding, the adhesive is clear.
These come in rolls of 2,000.
Example High Profile, Super High Tack
The Infinity Bond XD43-401 Glue Spots equate to the Glue Dots® brand XC43-401.
These form a permanent bond and have a high-profile thickness. These spots come in rolls of 1,000.
Industry Applications of Each Tack and Profile Type
Adhesive spots are excellent, low cost, solutions for a number of industries. The versatility of these adhesive products allows businesses to customize the use and incorporate dots into the manufacturing or assembly process the particular sector requires.
Mailing and Printing Company Use
Glue spots work well with any type of mail. Temporary adhesive dots make an excellent replacement for traditional wafer seals used to close packages and are United States Postal Office compliant.
A wafer seal will cover up your brand or logo, whereas a glue dot secures the package without masking it.
For example, you can attach brochure closures or promotional items and gift cards.
Medical, Including Pharmaceutical, Industries
Adhesive spots meet all regulatory requirements for mailing items related to the medical field. These adhesives meet pharmaceutical industry requirements for things like securing labels, applying inserts or closing cartons. You can safely secure medical information sheets to your packages.
Medicines and other pharmaceutical products will not become tainted by coming in contact with the glue used in the dots or spots.
Packaging Companies
Packaging companies can take advantage of this adhesive option during production. Glue spots eliminate any mess or heat and safety issues.
Packaging companies can use adhesive spots to affix labels easily, attach promotional items and adhere multi-packs to each other before shrink wrapping, and sealing cartons.
Manufacturing Assembly Lines
Glue Dots® can increase productivity by helping to seal items quickly and efficiently during production-line assembly and packing. The dots work quickly, so curing time is not a factor. You can easily add adhesive spots to your operations without an expensive machine or assembly line changes.
Glue spots can hold gaskets in place, keep various components of your product secure, close and seal packaging, and much more.
Food and Beverage Companies
Since Glue Dots® have been tested and confirmed as FDA compliant, the food and beverage industry can incorporate dots into their food and beverage packaging.
You can extend a product’s shelf life by securing adhering things like desiccants to the containers. Using Glue Dots® on labels or to attach coupons will not contaminate your products.
Last Word
Virtually any industry may find that adhesive spots can meet the company’s adhesive needs.
Hot melt may work best for some operations, but many find that other parts of their operation can benefit from the advantages of this versatile adhesive technology.