Dowsil 789 Clear 300ml

DOWSIL 789 Silicone Weatherproofing Sealant is a one part, neutral cure, architectural grade sealant. It easily extrudes in any weather and cures at ambient temperature by reaction with moisture in the air to form a durable, flexible silicone rubber seal.

Features

• All temperature gunability
• Primerless adhesion - upon curing will form a strong bond to most common building components without the use of a primer
• Long-life reliability - cured sealant stays elastomeric from -50°C to 150°C without hardening, cracking or becoming brittle under normal weather conditions
• Low Modulus with extension/compression capability up to ±50% of original joint width
• Excellent weatherability, virtually unaffected by sunlight, rain, snow etc.
• Ease of application - ready to use as supplied

Areas of Application

DOWSIL 789 Silicone Weatherproofing Sealant is a premium performance weather sealing product specifically designed for general glazing and weather sealing in curtain wall and building facades.

Method of Applicaiton

Preparation

• Clean all joints, removing all foreign matter and contaminants such as grease, oil, dust, water, frost, surface dirt, old sealants or glazing compounds and protective coatings.

Application Method

• Install backing material or joint filler, setting blocks, spacer shims and tapes.
• Mask areas adjacent to joints to ensure neat sealant lines.
• Primer is generally not required on non-porous surfaces, but maybe necessary for optimal sealant of certain porous surfaces. A test placement is always recommended.
• Apply DOWSIL 789 Silicone Weatherproofing Sealant in a continuous operation using a positive pressure. (The sealant can be applied using many types of air-operated guns and most types of bulk dispensing equipment.) 
• Before a skin forms (typically within 15~20 minutes), tool the sealant with light pressure to spread the sealant against backing material and the joint surfaces.
• Remove masking tape as soon as the bead is tooled.