When a local siding manufacturing company began experiencing substantial downtime from long clamping/pressing times with their adhesive, they turned to Hotmelt.com and Infinity Bond PUR to help.

At Hotmelt.com we are proud to offer some of the highest quality adhesive product to our valued customers. As well as high quality products, we are always striving to provide high quality information, so that we can be certain our customers understand that products are best suited for their specific uses. It is important that you know what you're buying, so we take our responsibility to inform seriously. This week, we're excited to share with you a customer's success with Polyurethane (PUR) adhesives.

exterior siding on residential home

Application Issues

The company we are highlighting today was experiencing issues with a specific application of bonding PVC to wood planking to make exterior siding for residential and commercial structures.

There are several factors to consider in selecting an adhesive. For exterior woodwork and siding, the biggest concerns are typically water resistance, strength, and cleanup. Working temperatures, clamping time, and gap filling abilities may also be important, depending on the specific job and conditions.

This specific company was using a urethane adhesive. Urethane foams up as it cures, expanding to three to four times its original size and filling and small gaps in the joint. But unlike epoxy, the filled caps have no strength. Clamping time is one to four hours, depending on the specific formulation. For maximum strength, clamp for 24 hours. This was becoming a problem for our customer. Long pressing/clamping times meant lost production.

Not every application is suited to urethanes. Their chemical resistance is affected by the urethane linkage, which can be attacked by acids or bases. They are not recommended for bonding metals exposed to high humidity. Like epoxies, urethanes can decrease in viscosity when heated, and they have a high coefficient of thermal expansion. Some urethanes contain isocyanates and heavy metal catalysts that pose health risks to workers.

When clamping is not practical, our experts at Hotmelt.com suggest hot melt polyurethane adhesive. Hot melt polyurethane (PUR) have been used in industrial settings for many years, but they are relatively new to job-site use. Unlike its moisture-cure cousin, hot melt PUR does not foam up, and needs very little clamping. It sets in about 30-60 seconds (depending on the product and application) and provides the same level of water resistance as a regular polyurethane.

Benefits of PUR adhesives showing weather resistance, reduced clamp time, and superior bond strength

What is PUR?

Polyurethane adhesives are not new to the marketplace, take a moment to dig into our Full Overview of PUR Adhesives. PUR is best described as a group of one-component, moisture curing, urethane adhesives. Infinity Bond's line of superPUR products were created to address the shortcomings of both traditional hot melt adhesives and those of industrial grade structural adhesives.

Polyurethane Reactive hot melt has a combination of different positive attributes found in various unique adhesives. PUR hot melt is not found in the normal form of a glue stick or bulk pellet, instead, it is melted from a solid prior to application and commonly dispensed from a 10oz tube similar to caulking adhesive. PUR hot melt solidifies through moisture in the air to form a super strong bond that will not re-melt. There are both high and low temperature PUR adhesives so make sure you are using the correct applicator when working with PUR products.

Because PUR is so strong, durable, has a fast set time, and minimal need for clamping, it was the perfect choice for the exterior siding application. Our customers were pleased with the results and couldn't wait to reduce downtime by switching to PUR adheives.


Sold out
Sold out
Sold out

Make the Switch to PUR

We understand polyurethane adhesives at Hotmelt.com, so if you're still not sure which PUR adhesive would be best suited for your project, drop us a line. Since one of polyurethane adhesive's great strengths is the huge variety of types of PUR adhesive, making the choice can seem overwhelming, but some of them are highly specialized and we'll help you cut the list down to a manageable size.

If you still aren't sure whether you need polyurethane adhesives or a different adhesive type altogether, we are happy to help! Since we have a wide range of adhesives available, we're very likely to have a product in stock that would suit our needs. We can't wait to hear from you!


Sold out
Sold out
Sold out

Shop all PUR products!

Ordering in bulk? Get your online bulk quote now!

Other questions? Call today (877) 933-3343

Ask a Question

Have questions? Our team of hot melt experts can help. Submit your questions and we'll get you answers right away. We're here to help.