So versiegeln Sie Risse richtig mit PU-Schaum

Sealing cracks with PU foam – Polyurethane foam spray has emerged as a popular and effective solution for sealing cracks in various applications, ranging from construction and home improvement projects to automotive and industrial uses.

This versatile material offers excellent insulation, adhesion, and sealing properties, making it a go – to choice for professionals and DIY enthusiasts alike. However, to fully harness the benefits of polyurethane foam spray and ensure a successful and long – lasting crack – sealing job, it is crucial to understand the proper techniques and considerations involved in its application.​

Polyurethane foam spray is a single – component, moisture – curing product. It typically consists of a polyurethane pre – polymer, a blowing agent, and various additives.

When the foam is dispensed from the can through a nozzle or gun, it expands rapidly upon contact with air and moisture in the environment. The blowing agent causes the foam to expand, creating a lightweight, porous structure that fills the crack and adheres to the surrounding surfaces. As it cures, the polyurethane foam hardens, forming a durable seal.

1. Building and Construction: In construction, polyurethane foam spray is widely used to seal cracks in walls, floors, ceilings, and around window and door frames. It helps to prevent air leakage, which can improve energy efficiency in buildings. For example, sealing cracks around windows with polyurethane foam can reduce drafts, keeping the interior of the building warmer in winter and cooler in summer. It can also be used to seal cracks in concrete foundations, preventing water infiltration that could lead to structural damage over time.​
2. Automotive Industry: In cars, polyurethane foam spray can be used to seal cracks in the bodywork, around windshields, or in the engine compartment. Sealing these cracks helps to reduce noise and vibration, improve the vehicle’s aerodynamics, and prevent water from entering the vehicle, which could cause corrosion.​
3. Industrial Applications: In industrial settings, polyurethane foam spray is used to seal cracks in pipes, tanks, and equipment. For instance, in chemical plants, sealing cracks in pipes carrying corrosive substances with polyurethane foam can prevent leaks and ensure the safe operation of the facility. It can also be used to insulate and seal cracks in industrial ovens or refrigeration units.

1. Clean the Area: Before applying the polyurethane foam spray, it is essential to clean the surface around the crack thoroughly. Remove any dirt, dust, grease, or loose debris. A clean surface ensures better adhesion of the foam. For example, in construction applications, if the surface has dust or grease, the foam may not bond properly, leading to a weak seal.​
2. Dry the Surface: Ensure that the surface is dry. Moisture on the surface can affect the curing process of the foam. In cases where the crack is in a damp area, such as a basement wall, it may be necessary to use a dehumidifier or allow the area to dry naturally for at least 24 hours before proceeding.

Shaking the Can​

Before use, vigorously shake the can of polyurethane foam spray for at least 1 – 2 minutes. This ensures that the components inside the can are well – mixed, which is crucial for consistent foam quality and expansion.

Applying the Foam​

1. Positioning: Hold the can or gun at a 45 – degree angle to the crack. Start at the bottom of the crack if it is vertical or at one end if it is horizontal. Insert the nozzle or gun tip into the crack, about 1 – 2 inches deep.​
2. Spraying: Slowly depress the trigger or valve to release the foam into the crack. Fill the crack gradually, moving the nozzle or gun along the length of the crack. Be careful not to over – fill the crack initially. As the foam expands, it will fill the remaining space. For small cracks, a light, continuous stream of foam is sufficient. For larger cracks, it may be necessary to apply the foam in layers.

Post – application Steps​

Trimming and Finishing​

Once the foam has fully expanded and cured (this usually takes a few hours, depending on the product and environmental conditions), use a sharp knife or a foam trimmer to cut off any excess foam that protrudes from the crack. Make the cut as flush as possible with the surrounding surface. After trimming, the surface can be further finished with sandpaper or a file to make it smooth. ​

Protecting the Cured Foam​

Polyurethane foam is sensitive to ultraviolet (UV) light. If the sealed crack is in an area exposed to sunlight, it is recommended to cover the cured foam with a paint, sealant, or other protective coating. This helps to prevent the foam from deteriorating over time due to UV exposure. For example, in outdoor applications, a coat of exterior paint can extend the lifespan of the foam seal.

Properly using polyurethane foam spray for crack sealing requires careful preparation, correct application techniques, and attention to safety.

By following the steps outlined in this article, you can effectively seal cracks, creating a durable, air – tight, and water – tight barrier. Whether you are working on a small home repair project or a large – scale construction job, using polyurethane foam spray correctly will ensure optimal results and a long – lasting solution for your crack – sealing needs.