Polyurethane Based Glues

Polyurethane Based Glues

Polyurethane glues, sometimes called Gorilla Glue, are one of the most versatile glues around. They work well on wood, metals, rubbers, plastics, tile and glass as well as concrete and brick.

This type of glue requires moisture to set, but can withstand extreme cold and hot temperatures. It also expands as it sets, filling in small gaps and making for a tighter bond.


A polyurethane adhesive is a strong and durable glue used for bonding a wide variety of materials. They offer good chemical and impact resistance, while also being capable of working in extreme temperatures. They are available as one-part or two-part glues and come in many forms such as caulking tubes with filler to prevent sagging, spray bottles and single use packages.

Polyurethane glues are able to bond both porous and nonporous surfaces such as wood and metal. They require moisture to set and expand as they cure, which can help fill gaps. However, this expansion can also push parts apart if they are not clamped properly. A rough surface can help the adhesive achieve a stronger bond by increasing the friction between the pieces to be glued together.

PU glues are also water resistant and can be painted after application. They are often used in the automotive industry to bond components, such as windscreens, to the frame of a vehicle because they are durable and provide excellent safety standards. However, a cured PU adhesive does contain isocyanates which may cause occupational asthma.

A PU glue can be polyurethane based glues either elastic or rigid depending on its chemical composition. The elastic 2K glues are thermoplastic and can be heated to allow reworking, while the rigid 1K glues are a thermoset and cannot be reworked.


Besides being a versatile adhesive that can bond to nearly anything, PU glue is also an excellent sealant. It seals well in damp and humid environments, keeping the materials it bonds together intact. Its heat and moisture resistance make it an ideal construction material for wood, metal and fiberglass. It can also be used in the automotive industry to glue windshields and other parts together.

This type of polyurethane glue is available as single- or dual-component adhesives. Both consist of a resin and a hardener that are mixed together prior to use. A range of chemicals can be integrated into the dual-component adhesive to adjust its chemical and physical properties for specific applications.

Both types require a bit of work to mix and apply. However, the finished product is more flexible than silicone sealants and can accommodate movement in up to 50%. They also keep water and air out and prevent leaks.

Polyurethane glue is available in both rigid and elastic versions depending on the chemical composition. The elastic variants are thermoplastics that can be reworked after curing, while the rigid ones are not. When working with this type of glue, it is recommended to wear nitrile gloves and work in a well-ventilated area. It is toxic and should be handled with caution. The vapors can cause irritation to the eyes and nose.


Caulking is the process of sealing joints to prevent water leaks, air infiltration, or heat loss. It’s also used to seal gaps around windows and doors, drywall and trim, or between masonry pieces. Several types of caulking are available, including silicone and butyl rubber, which stand up well to weathering, and a urethane-latex blend that resists moisture, mold, and fungus. Caulking is often used in addition to mechanical seals, such as ring seals around pipes or conduits.

Polyurethane glue is ideal for caulking because it’s waterproof and can be painted once cured. Its expansion properties also help it fill small gaps between materials. Most PU adhesives start out liquid and expand as they react with moisture, similar to expanding foam insulation. This property is an advantage when gluing wood together because it helps fill gaps and ensures that the bond will be strong.

The best PU glue for caulking is a 2K adhesive, which requires two components-an adhesive and hardener-to be mixed in a specific ratio before application. It’s important to follow the manufacturer’s instructions carefully, especially for prep and set times. Depending on the type of PU, you may need to roughen up the surface of the material you’re gluing or clean it with degreaser or acetone. Unlike some ordinary adhesives, 2K PU glues can be used on both porous and non-porous surfaces.


PU paintable glues are an excellent multi-purpose adhesive that work on both porous and nonporous surfaces. They can even join dissimilar materials such as wood to metal. They can also be used in extreme temperatures. The polyurethane base in the glue allows it to withstand high temperatures, making it ideal for outdoor projects or use near water. It is also very strong, allowing for a sturdy and long-lasting bond.

Unlike PVA glues, which have a short polyurethane based glues shelf life, a polyurethane adhesive can last for 18 months or more once opened. It is also solvent free and contains a very low amount of VOCs, which makes it safe for the environment. It can be sanded, stained and painted with ease, as well as being flexible and able to withstand stress. It also has excellent resistance to chemicals, so it can be overpainted.

The main drawback of a PU adhesive is that it can be messy and is more difficult to clean up than other types of glue. It also has a limited working time, so it’s important to clamp the pieces together tightly while the glue sets. It can also be more expensive than other glues. However, it can be a great option for any project that requires a strong and durable glue that is waterproof. Alternatives include wood glue, epoxy and cyanoacrylate glue (CA). Each has its own unique properties and advantages.

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