• High modulus (strength + flexibility) — maintains robust seals even in humid, wet areas
• Fungus & mildew resistant — ideal for bathrooms and kitchens
• Excellent adhesion to non-porous substrates (glass, aluminium, painted wood)
• Fast tack-free time (~20 minutes), full cure in 24 hours (for 2.5 mm depth) 
• Durability under UV, ozone, and temperature extremes — lasting clean performance

1. Surface Preparation - Ensure all surfaces are clean, dry, and free from frost. Remove any old sealant, dust, oils, or residues that might interfere with adhesion. For non-porous surfaces, wipe with a suitable solvent (e.g. R-40 Universal Cleaner) using an oil- and lint-free cloth. 

For porous substrates, mechanical cleaning (wire brush, sanding) may be required.

2. Masking & Nozzle Preparation - Mask the edges of the joint to achieve neat lines. Cut the nozzle at a 45° angle to produce the desired bead width; insert into a standard caulking gun.

3. Apply Sealant - Maintain a continuous, smooth bead of Dowsil C50 along the joint. Ensure full contact with both sides of the substrate. Avoid laying the sealant as a string — it should properly wet both edges of the joint.

4. Tooling - Tool the bead immediately (within the open time) using a suitable tool or your finger (wet with soapy water). This helps to shape and compress the sealant into the joint properly.

5. Curing - Dowsil C50 has a tack-free time of approximately 20 minutes. The full cure for a 2.5 mm thick layer is around 24 hours, though thickness and environmental conditions (temperature, humidity) will affect cure speed. 

Avoid disturbing the seal or exposing it to water until it has at least skinned over sufficiently.

6. Joint Design Tips - For joints under 12 mm wide, maintain a width-to-depth ratio of approx. 2:1 (i.e. depth ~ half the width). For joints wider than 12 mm, use a backer rod or bond-breaker tape to avoid three-sided adhesion. 

Minimum sealant bite (contact length) recommended is 6 mm per substrate, depending on design.