With the number of rubber glues available today, it is indeed difficult to pick the right adhesive to use. Aside from the fact that there are dozens of types of rubber glue, the majority of millennials and today’s generation grew up learning that it is better to dispose of things rather than to repair them.
On the other hand, it is still not too late to learn how to repair things via rubber bonding! And if you came here for that exact reason, then this article is for you.
What Is Rubber Adhesive?
Also known as cow gum, a rubber adhesive is a type of glue that is primarily made from latex or elastic polymers mixed in a solvent to keep the mixture fluid enough. They usually are mixed in a solvent such as toluene, acetone, heptane, and hexane.
For that reason, rubber cements are considered part of drying adhesives. Essentially, it means that as solvents evaporate, the rubber solidifies and forms a tough yet flexible bond.
Rubber adhesives are used in almost all industrial work. From roofing, floor coverings to general repair of consumer products, rubber bonding via rubber-specific adhesives are integral.
Rubber Bonding: Picking the Right Glue
Using the right type of glue is crucial to ensure that the object subjected to bonding is firmly placed. But as I mentioned earlier, rubber adhesives are available in dozens of forms. And to choose which one is the appropriate glue would be difficult.
That being said, here’s how to pick the right rubber adhesive to use.
Step 1: Learn the 3 Types of Rubber Adhesives
First thing first: you must learn the three common types of rubber cements. And these are cyanoacrylate adhesives, silicone-based adhesives, and two-part structural adhesives.
Here’s how the three differ.
Rubber glues that are based on silicone are the most versatile type of adhesive among the three. It can be used in almost all types of rubber but is specifically made for silicone rubber type. Its setting speed takes a while too, which offers flexibility even after curing.
Apart from that, silicone-based adhesives can withstand moisture and certain chemical reaction too. It can also resist extremely high temperatures and some formulas can even provide electrical conductivity and insulation.
The only catch is that the application might be messier compared to other rubber adhesives due to its slow setting speed.
Commonly known as the “super glue,” a cyanoacrylate is a type of rubber cement used generally for all types of rubber bonding. It is an acrylic resin with cyanoacrylate or acrylic monomer as the main ingredient, which turns into plastic after a few minutes of curing.
Unlike silicone-based adhesives, those with cyanoacrylate as the main ingredient is also known for their quick curing time. Generally, this type of adhesive has a set speed of around 5 to 60 seconds—and that’s quite quick!
On the other hand, while its setting speed is an advantage for some, it could also pose problems for others. It is especially true with projects that require a longer setting period. Or you simply want some flexibility.
Moreover, rubber cements of the said form may not stick firmly specifically if the type of rubber subject for bonding is natural or EPDM. In such a case, professionals recommend using a primer or cyanoacrylate that is developed specifically for the hard-to-bond type of rubbers.
Two-part structural rubber glue is typically used to bond “difficult” plastics like polyethene and polypropylene. It is often used in projects that require flexibility. It is because its curing time is slower than cyanoacrylate–based adhesive, making it perfect for accurate spreading and alignment.
Step 2: Check the Properties of Rubber Adhesives
For rubber glues to successfully work, you must understand as well what kind of property you need for a particular type of rubber. Strong adhesion, for example, is the most common attribute that people find when it comes to rubber adhesives. Such type of glue—cyanoacrylate or super glue, to be exact—is generally used for all types of rubber. Adhesives with strong adhesion are particularly handy for rubber that is soft like the sole of rubber shoes.
But not all rubbers require such glue, especially if you are looking for some flexibility while working. And that is where adhesives that offer versatility take the spot.
Apart from that, you must also take into account the adhesive’s curing time or setting speed. This type of glue is great for beginners who are working on important projects. It allows you to adjust things, specifically if you messed up.
Lastly, some rubbers need adhesives with great elasticity too. If you are working on, say, fixing an inflatable float or a hose, a type of glue that does not crack when bent is highly recommended. That said, when looking for such a type of adhesive, check the product’s sulfur content. If the amount of sulfur is high, then the glue is less likely elastic. Hence, choose only an adhesive with low sulfur content.
Step 3: Identify the Type of Rubber
Lastly, you need to identify the style of rubber subject for bonding as well. It is because there are formulas of rubber cement that are rubber specific.
- Silicone rubber. This type of rubber is extremely resistant to heat. It is typically used for cookware, prosthetics, and medical devices.
- Natural rubber. This type of rubber is commonly utilized for gaskets, carpet backing, and seals.
- EPDM rubber. EDPM is usually found in seals and automotive hoses.
- Polyurethane rubber. This type of rubber is typically used for molds and modeling.
- Butyl rubber. This type of rubber is usually used in valve seating, linings, seals, and stoppers.
Final Thoughts
Whether it is to repair an old, broken item or working on an important school or work project, picking the best adhesive for rubber bonding is indeed not a walk in the park. It is crucial that you take some factors into consideration. Assessing the type of rubber subject for bonding as well as the adhesive property it needs, for example. Otherwise, the rubber might not successfully bond.
