Frame foam – the PU foam specialist for interior doors
Doors should absorb day-to-day impacts without wobbling. This is why there is special frame foam that is used to attach door frames allowing them to withstand continuous heavy loads. What properties does this foam need? Frame foam needs to be highly adhesive and strong, and also needs to harden quickly and reliably. Also, it should be dimensionally stable after a very short time and not spread.
Quality properties of frame foam
The strength of the foam ensures that the door remains tightly in position for many years. This property is reflected by the bulk density of the selected PU foam; it should lie between 25 and 30 kg/m³. Short hardening times minimise the assembly process. Ideally, the frame foam is no longer sticky after five to eight minutes, and can even be cut after eight to twelve minutes. Another factor is important for the assembly process. To ensure that the PU foam does not compress the door frame during its hardening ad expansion process, it needs to be held in position with struts.
The strut removal time states the amount of minutes that need to pass before the strut can be safely removed. This is usually the case after half an hour; it has reached its full strength after about four hours. To check the values of the PU foam used, we recommend checking the packaging or, even better, the product data sheet. All times and data are stated here.
Mounting interior doors with frame foam
Here, only 20 to 30 percent of the upright frame surface needs to be adhered, when mounting the door frame. To do this, apply the frame foam at six to eight points of the door frame, preferably at about the same level as the hinges. This is where the struts are also attached. No additional attachments are required when mounting interior doors. The surface of the door frame should be strong, clean, and free of dust and grease to ensure good adhesion of the frame foam. Frame foam will adhere to almost all on-site surfaces, for instance wood, concrete, brick, metal or aluminium. There are some restrictions in the case of plaster, glass and ceramics. PU foam will not adhere to polyethylene, polypropylene, silicon and oily surfaces.
Frame foam with two components
Usually, frame foam is a 2-component PU foam that does not require air moisture to harden. Instead, the can contains a second hardener component that the user needs to activate before use. The advantage of the 2-component (2K) frame foam lies in the controlled hardening process and high strength that 2K PU foams reach.
Advice when using frame foam:
- Wear goggles and protective gloves at work to protect skin and eyes against any PU foam splashes, and ensure the work area is ventilated well.
- Remove the lid and, depending on the product, unscrew the supplied adapter or the PU foam gun.
- To activate the hardening component, turn the plate or rotor on the base of the can approx. six times in the direction of the arrow. The instructions provided by the manufacturer are decisive here.
- Shake the can thoroughly before use (approx. 30 times) with the valve facing downwards, so that the frame foam and its hardener are mixed well. This is important because the foam quality depends on how well the two substances have been mixed.
- Hold the can with the valve facing downwards and apply foam immediately. You can regulate the quantity of foam by pressing the lever.
- If the foam has an uneven colour, shake the can again thoroughly.
- The emptying process must be completed in approx. 8 to 10 minutes. Then the foam hardens in the can.
- Spent cans should be recycled. More information at www.pu-schaum.center/en/sustainability/recycling.html