Sikasil® WS-305 S Weatherproofing sealant
- Meets requirements of GB/T14683-2017
- Outstanding UV and weathering resistance
- Adheres well to many substrates including glass, metals, coated and painted metals, plastics and wood
Sikasil® WS-305 S can be used for weatherproofing and sealing applications where durability under severe conditions is required.
Sikasil® WS-305 S is particularly suited as a weather seal for curtain walling and windows.
This product is suitable for professional experienced users only. Tests with actual substrates and conditions have to be performed to ensure adhesion and material compatibility.
Sikasil® WS-305 S cures by reaction with atmospheric moisture. The reaction thus starts at the
surface and proceeds to the core of the joint. The curing speed depends on the relative humidity and the temperature (see diagram 1). Heating above 50 °C to speed-up the vulcanization is not advisable as it may lead to bubble formation.At low temperatures the water content of the air is lower and the curing reaction proceeds more slowly.
Surface preparation
Surfaces must be clean, dry and free from oil, grease and dust.
Advice on specific applications and surface pretreatment methods is available from the Technical
Department of Sika Industry.
After suitable joint and substrate preparation, Sikasil® WS-305 S is gunned into place. Joints must be properly dimensioned as changes are no longer possible after construction. For optimum performance the joint width needs to be designed according to the movement capability of the sealant based on the actual expected movement. The minimum joint depth is 6 mm and a width / depth ratio of 2:1 must be respected. For backfilling it is recommended to use closed cell, sealant compatible
foam backer rods e.g. high resilience polyethylene foam rod. If joints are too shallow for backing material to be employed, we
recommend using a polyethylene tape. This acts as a release film (bond breaker), allowing the joint to move and the silicone to stretch freely.
For more information contact the Technical Department of Sika Industry.
Tooling and finishing
Tooling and finishing must be carried out within the skin time of the adhesive.
When tooling freshly applied
Sikasil® WS-305 S press the adhesive to the joint flanks to get a good wetting of the bonding surface.
