Joint surfaces must be clean and free from frost and surface water. Remove all dirt, Iaitance, loose materials and foreign matter.
- Remove alI rust, scale and protective lacquers from metal surfaces.
- Non-porous surfaces should be degreased using Sika Thinner C
- In all joints a bond breaker must be used to prevent sealant contact with the back of the joint, and hence allow optimum performance. In shallow joints self adhesive polyethylene tape can be used. Deep joints should incorporate a backing strip such as Sika PEF Rod to support the sealant while also acting as a bond breaker.
PRIMING
Sikaflex® MS adheres to many substrates without primers and/or activators. However, for optimum adhesion and critical, high performance applications, such as on multi-story buildings, highly stressed joints or extreme weather exposure, the following priming and/or pretreatment
procedures shall be followed:
Non-porous substrates
Aluminium, anodised aluminium, stainless steel, PVC, galvanised steel, powder coated metals or glazed tiles have to be cleaned and pre-treated using Sika® Aktivator- 205, wiped on with a clean towel. Before sealing, allow a flash-off time of > 15 minutes (< 6 hours).
Other metals, such as copper, brass and titanium-zinc, also have to be cleaned and pre-treated using Sika® Aktivator-205,wiped on with a clean towel. After the necessary flash-off time, use a brush to apply Sika® Primer-3 N and allow a further flash-off time of > 30 minutes (< 8 hours) before sealing the joints.
Porous substrates
Concrete, aerated concrete and cement based renders, mortars and bricks shall be primed using Sika® Primer-3 N applied with a brush. Before sealing, allow a flash-off time of > 30 minutes (< 8 hours).
For more detailed advice and instructions please contact the local Sika Technical Services Department.
Note: Primers are adhesion promoters. They are neither a substitute for the correct cleaning of a surface, nor do they improve the strength of the surface significantly.