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Silicone is known to many as a sealant, especially in the sanitary sector. However, not everyone knows that it can also act as a very potent adhesive. This guide will explain exactly what a silicone rubber adhesive is and how you can achieve optimum results in silicone repair.
Table of Contents
What Is Silicone?
Silicone belongs to the polysiloxanes group. They are often counted among the synthetic polymers, but this is not completely correct. They were discovered at the beginning of the twentieth century during extensive experiments with silicone as well as silicone compounds by Frederic Stanley Kipping. Since 1940, large batches of silicone have been produced industrially. Silicone has many useful properties that are appreciated by both home users and industry.
Furthermore, it always behaves the same, even under large temperature fluctuations.
Silicone is widely used as a sealant in particular, but also in the form of oils and elastomers. It is highly glossy and proves particularly useful in damp rooms for filling joints. Here, it is particularly ideal in expansion joints, as it has highly elastic properties when cured. There are also silicones available on the market that have a mild fungicidal effect and thus prevent mold. Other applications of silicone are:
But silicone also proves its worth in another area of application – as an adhesive.
Advantages and Disadvantages of Silicone-Based Glues
A silicone rubber adhesive offers the user many different advantages:
Application Areas for Silicone-Based Glues
The areas of application for silicone adhesives are diverse. For example, materials can be reliably bonded together, especially outdoors, where the adhesive seam must be weather-resistant and waterproof. Bonding and attaching tiles is also no problem with a silicone rubber adhesive. The following materials are reliably bonded with silicone-based glues:
Many users place particular emphasis on the ease of processing and flexibility of silicone, which is ideal for bonding substrates that are permanently exposed to vibrations or temperature fluctuations, such as:
The Best Adhesive for Silicone
Before you choose a silicone adhesive, you need to ask yourself whether it should be a one-component (1k) or a two-component (2k) adhesive. Generally, a silicone rubber adhesive is supplied in a cartridge that is practical to use. With this choice, it depends in particular on the subsequent load on the adhesive seam: While 1k silicone adhesives is unable to withstand greater loads, the 2k silicone adhesive is able to withstand a higher burden.
The curing time also tends to be longer with a one-component adhesive than with a two-component adhesive. One argument in favor of the one-component adhesive is the lower price compared to the 2k variant. With the 1k silicone, you should also pay attention to the color, because it is often strikingly brown. However, transparent adhesives are also available. We took a look at various adhesives for silicone and chose two winners, which we would like to present to you below.
Best Premium Silicone Rubber Adhesive: GE SEALANTS & ADHESIVES Advanced Silicone Sealant
This silicone rubber adhesive by GE Sealants & Adhesives offers an extremely durable and top-quality product for your adhesive needs. This silicone glue is resistant to all kinds of weather, protecting against freezing, UV exposure, and water, and more.
In fact, this adhesive will not shrink or crack in the face of drastic temperature changes. You can use this silicone adhesive on metal without worrying about it leaving a discolored blemish mark. This product also prevents staining from mold, mildew, and water damage.
With a lifetime guarantee, you can only expect top-quality results when using this silicone rubber adhesive.
Best Affordable Silicone-Based Glue: LOCTITE Clear Waterproof Silicone Sealant
This easy-to-use tube of silicone-based glue is ideal for sealing and repairing all kinds of surfaces around the home. Being waterproof, this sealant can also be used for fresh- and salt-water aquariums. Loctite’s clear silicone sealant will not crack, peel, or shrink, and it can be used both indoors and outdoors. You can apply this sealant to surfaces such as wood, glass, porcelain, plastic, metal, and more.
This is the ideal choice for those wanting an affordable silicone adhesive that will work with great effect in and around the home.
How to Glue Silicone
If you want to try your hand at bonding with silicone-based glues, there are several things that you need to keep in mind. In our silicone bonding step-by-step guide, we tell you what these are.
The following things are needed for gluing with silicone:
- The silicone
- A spray gun for the silicone cartridge
- A spatula and a lint-free cloth
- Water and washing-up liquid; alternatively, acetone or isopropanol
Before you can bond the silicone, you must clean the substrates thoroughly. These must be free of any dirt, dust, oil, and grease. Any old grout must also be removed before you can bond new tiles with silicone, for example. The tiles to be laid or the other substrates can be cleaned with by rinsing it with water, but also with isopropanol or acetone.
Allow the surfaces to dry completely before starting the silicone bonding process. If the substrates show very uneven areas, these must still be filled or the surrounding raised areas must be ground down. Silicone is not suitable for bridging large gaps during the bonding process.
Now, you can make the cartridge ready for use. Depending on the manufacturer, you may still need to screw on a nozzle. You may also have to put the cartridge together with a gun. Follow the manufacturer’s instructions for use.
The Bonding Process
Before you apply the silicone adhesive to the actual substrates, it is recommended that you practice on a piece of cardboard. If the handling works well, you can apply the adhesive for silicone to the substrates.
Silicone beads are now applied to one side of the entire surface to be bonded. If it is a large area, set the beads tighter and apply the silicone more generously, but not too thickly.
The two substrates are now joined carefully but with high pressure. Fix them if necessary so that the adhesive seam has time to harden. Immediately pick up any escaping silicone adhesive with a spatula and wipe carefully with a paper towel or lint-free cloth.
You can also perform the last step with a finger if you are wearing disposable gloves. This is recommended anyway when working with glue. Make sure to use gloves made of nitrile to prevent allergic reactions, which can occur with latex.
Drying and Load
The drying time cannot be determined in general, as it depends on the silicone adhesive used. Please refer to the manufacturer’s data sheet. Generally, a silicone rubber adhesive needs 24 hours to cure completely. However, it is better to give the substrates a little more time.
Our guidebook will not only deal with the actual silicone adhesive, but also with the bonding of silicone surfaces, because this has its pitfalls. It is not for nothing that silicone is often used as a release liner for adhesive tapes or labels. It is a low-energy surface that makes it impossible to use conventional adhesives. The adhesive would simply roll off the surface.
Fortunately, however, state-of-the-art industrial silicone adhesives are available that make it possible to bond silicone surfaces. Such adhesives are based on alpha-cyanoacrylic acid methyl ester and are used like normal adhesives.
Important in this bonding process is the preparation of the substrates. They should be thoroughly cleaned of all grease, dust, oils, and dirt deposits. Another important prerequisite is the accuracy of the fit of the substrates. The more optimally the substrates fit, the better the adhesive will work.
Such highly effective industrial adhesives must flash off for several minutes after application. The exact length of this flash-off time should be taken from the data sheet. Any leaking adhesive for silicone must be removed immediately, as this can be a major problem after curing.
Tips and Tricks
- Adhesive tapes for low-energy surfaces are an alternative to the above-mentioned adhesive for silicone. They also bond surfaces with silicone coatings reliably and permanently. They are easy to use and heat-resistant. However, they are relatively expensive.
- After each use, the silicone gun should be thoroughly cleaned, otherwise it will clog.
- If you work with silicone in places that are exposed to large temperature fluctuations, you should use a backfill cord. This is particularly suitable for grouting or sealing windows and countertops in the bathroom and kitchen.