Typically, as you would anticipate summer is the busiest period for insulating properties using the most popular method of polyurethane in the form of spray, non-other than V-PUR-S-97L. Mainly due to the nice weather, high temperatures and low humidity levels. Even though the application process might sound pretty straightforward there are a number of factors that could, if not taken into consideration, create problems. Hence why we feel that this article would be useful as it highlights all these elements & gives a few tips so you can get a guaranteed successful end result.
- Weather Conditions
- Ambient temperature higher than 15oC
- Atmospheric humidity less than 60%
- Avoid spraying under windy conditions
- Substrate Condition (concrete, cement) and Preparation
A)Concrete should be cohesive and not looseCohesive strength of concrete must be higher than 1.5 N/mm2.
When in doubt regarding the substrate’s cohesion, or the cohesive strength is less than the value mentioned above, the use of a primer is mandatory.
B) The concrete should be CLEAN and DRY
Furthermore, any kind of paint, whether this is aliphatic PU or any other type, previously applied on the concrete surface, MUST BE REMOVED, so that no trace is left.
- Substrate and environmental conditions prior to application
- Substrate moisture (Hsub) must be less than 4%
- Substrate temperature (Tsub) must be higher than 15oC
- Dew Point (tdew) must exceed substrate’s temperature by more than 3oC
- During spraying process, make sure that the pressure and temperature values are on manufacturer’s specifications.
- The flatness of the foam, following the spraying process, depends on a number of factors, such as:
- Weather conditions (Wind levels during the process)
- The type of gun used (mechanical or air purge ) and the mixing chamber (size, type)
- Applicator’s experience
- Keep a steady tempo while spraying.
- Maintain a certain distance from the surface that will guarantee the best possible results.
- While spraying, a parallel movement from the surface and not a curved one should be achieved. This can be guaranteed through a steady wrist.
- A cooling period of time between each layer is mandatory in order to avoid layers’ delamination or foam’s self-ignition.
- Apply all layers on the same day.