A Guide On Polyurethane Sealant: What You Need to Know

Are your pipe joints on the roof collecting rainwater? If you catch yourself nodding to this question, there is a high likely chance that it has not been fixed using the polyurethane sealant.

In general, a sealant is an insulating and grouting material specially used for filling gaps, and preventing water and air from getting into joints as well as absorbing the natural movements of building materials. When it comes to sealants, silicone and polyurethane are the two commonly known types.

What is Polyurethane Sealant?

The polyurethane sealant plays a crucial role where middle bond strength is needed. The polyurethane sealant is a single-component elastomeric sealant for air and water-tight seals. As such, once it has been cured, it can be painted over with little to no problems.

Different types of polyurethane sealant

For sealing purposes

Polyurethane sealants are classified based on their estimated hardness. If the hardness is up to 45, it falls under ‘low modulus’ referring to sealants that are useful for joints between prefabricated building elements, rainwater collection pipes, gutters, precast concrete blocks as well as aluminum pipes found in highly ventilated areas.

For bonding purposes

Any polyurethane sealant ranging in hardness from 45 and above, comes under ‘adhesive sealants’. This type is said to be highly useful for the vehicular and automotive industries where the manufacturing process involves air-conditioning in HVAC systems, auto glass repair, and metal sealing for large trucks and containers.

Benefits of using Polyurethane Sealer

• Easy and no-fuss application
• Resistant to corrosion and climatic conditions
• Remains elastic after curing

How to use: application and procedure

1. Prepare the surface

Before you begin to use the sealant, there are a few things to keep in mind: a clean, dry surface with no water. The surface to be applied should be squeaky clean and free of dust, debris, crumbly particles and rust from metals.

It is advised to use a grease remover to clean the surface thoroughly.

In the case of a metal surface, it should go through a few cleanings on repeat. Concrete drying shrinkage should be completed before sealing.

Depending on the depth of the joint, a backing rod is installed to evade the three-point adhesion. Next, the masking tape seam is used next to the joint so that the sealant doesn’t stain the substrate from excess spilled out sealant.

2. Applying the adhesive sealant

To begin with sealing, the application tip needs to be cut. Nozzle tips are usually tapered ,so you should trim the nozzle according to the bead size you desire.

For superior efficacy and bonding, a sausage tube is used. The wire at the clamped end is cut and fitted with the open end towards the nozzle into a fully enclosed caulk gun.

A test stream can be done to check if the bead size is accurate.

A generous amount of the sealant is squeezed out into the joint so that it comes into full contact with the joint faces. Using a spatula will help smooth out the liquid glue.

Within 10-25 minutes after application, the masking tape is gently removed. Thereafter, any uncured material is also eliminated with a compatible solvent or sealant remover.

Buy our Weberseal PU from Saint Gobain

At Saint Gobain, we recommend the Weberseal range, which comes in 600ml with a shelf life of 12 months, is a high-quality polyurethane sealer and adhesive that is applicable for seam sealing or sealing of pipe ducts and ventilation systems. As a highly versatile material, the adhesive strength in PU sealant can positively influence wood building and metal bonding. It is also available in three colours: black, grey, and white. For more information about the product, check out our website or give us a call on +65 63308288 today!