Low temperature application
How to reach best results at low temperatures
At temperatures below 0°C, there are several hurdles the products need to overcome to help to work efficiently - the cure rate of sealants and PU foams is diminished and there is the possibility of presence of ice and frost on bonding surfaces. The air humidity levels are extremely low at these temperatures, which from one side causes low curing rate of the silicone sealants, from other side only special PU foam products can be used on these conditions.
General guidelines for low temperature applications:
- Warm the PU foam can or sealant cartridge to room temperature. This will help to ensure adequate foaming speed or flow of the sealant and ensures the best adhesion after application.
- Clean any frost or ice from the substrates. When moisturising the substrate, ensure that the ice is not formed!
- If possible, warm the bonding surfaces prior to surface preparation e.g. with the help of warm air blower. Raising the temperature of the substrate improves the adhesion of the sealant to the surface.
- PU foam cure very slowly at low temperatures. Premature cutting of the foam, while the structure has not achieved the final strength, can affect the overall filling of the joint. Expansion and yield characterictics of the PU foams vary gravely with the temperature changes.
- In case of acrylic sealants: water based sealants may freeze when stored at temperatures lower than 0°C. Care should be taken to store this sealant at temperatures warmer than +5˚C and the storage instructions for specific product to be followed.
- Silicone sealants should also be stored and applied in accordance with the application procedures listed for each product. The silicone sealants will cure at a slower rate at lower temperatures due to the lover levels of air humidity, warming the sealant cartridge prior to use will improve the sealant’s flow properties.
- Condensated water on the surfaces affects adhesion of both PU foams and sealants. If the temperature is below the dew point, the affected substrates should be cleaned to remove the condensation before PU foam or sealant application.
- Wind effect - the main effect of wind is the accelerated cooling, which affects both the substrates and PU foams or sealants. This will directly affect the time available for surface preparation and product application. Blowing wind can reduce the temperature on the surface significantly, causing even slower curing speed and adhesion problems.
- Environmental conditions can vary day to day, therefore any project should be evaluated on an individual basis.