The substrate must be sound, clean, dry and free of all contaminants such as dirt, oil, grease, cement laitance, old sealants and poorly bonded paint coatings which could affect the adhesion of the sealant. The substrate must be of sufficient strength to resist the stresses induced by the sealant during movement. Removal techniques such as wire brushing, grinding, grit blasting or other suitable mechanical tools can be used. All dust, loose and friable material must be completely removed from all surfaces before application of any activators, primers or sealant. For optimum adhesion and joint durability, the following substrate priming (and/or pre-treatment) procedures must be followed:
Non-porous substrates
Aluminium, anodised aluminium, stainless steel, galvanised steel, powder-coated metals or glazed tiles. Slightly roughen surface with a fine abrasive pad. Clean and pre-treat using Sika® Aktivator-205 applied with a clean cloth. Before sealing, allow a waiting time of > 15 minutes (<6 hours). Other metals, such as copper, brass and titanium-zinc, should be cleaned and pre-treated using Sika® Aktivator-205 applied with a clean cloth. Allow a waiting time of > 15 minutes (< 6 hours). Glass must be cleaned with Isopropanol before application.
Porous substrates
Porous substrates, specifically cement-based, must be primed with Sikagard® 62 or coated with Sikadur®-31 DW. For Sikagard® 62 before bonding/sealing, allow 30 hours for the Sikagard® 62 to fully cure. For Sikadur®-31 DW apply at a minimum thickness of 2 mm, maximum 30 mm, and allow 5 hours / or until hard. For more details such as application and flash-off times, refer to the most recent Product Data Sheet of the respective pre-treatment product. Adhesion tests on project-specific substrates must be performed and procedures agreed with all parties before full project application. For more detailed advice and instructions contact Sika Technical Services.
Note: Primers and activators are adhesion promoters and not an alternative to improve poor preparation /cleaning of the joint surface. Primers also improve the long term adhesion performance of the sealed joint.