How to Caulk With Sikaflex

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Things You'll Need

  • Sikaflex

  • Caulking gun

  • Masking tape

  • Mineral spirits

  • Rags

Sikaflex is a strong, polyurethane-based caulk. Sikaflex is sun and moisture resistant and is frequently used for sealing parts of a boat. It can be used to seal decking joints, around windows or gaskets, and it can substitute or help strengthen and reinforce other modes of fastening. It is also often used in auto body repair. Be sure to research the different types of Sikaflex and choose one that is appropriate to your needs. Sikaflex caulking should not be done in temperatures below 40 degrees F.


Step 1

Thoroughly clean the areas to be caulked. Make sure they are free from oil, grease and dirt. Allow time to dry before caulking.


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Step 2

Mask around the joints and seams to be caulked with masking tape. This will prevent caulk from getting onto surrounding surfaces and will help you create an even, professional looking caulk line.


Step 3

Puncture the extrusion seal of the Sikaflex cartridge with the caulking tip. Attach the caulking tip to the cartridge. Insert the cartridge into a caulking gun. A power operated caulking device can also be used. Cut off the end of the plastic tip on the cartridge at a 45-degree angle.


Step 4

Place the angled tip downward and squeeze the caulk into the joint or seam. Move the caulking gun along the joint or seam at a slow and steady speed. Make sure that the bead is wide enough to fill the joint or seam and try to keep it uniform.


Step 5

Use your finger to smooth down the caulk. Dipping your finger in soapy water will help your finger to glide more smoothly down the caulk line. Wipe away any unwanted smears with mineral spirits and a rag. Remove masking tape.


Step 6

Compress the joint with clamps or fasteners, if possible, to ensure a watertight seal. Keep the clamps or fasteners attached until the Sikaflex has cured. Curing time depends on the type of Sikaflex being used.


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