838 Coatings - MS Sausage, Multi-Purpose Sealant, 20oz, White

838 MS is a hybrid moisture-cure elastomer sealant formulated to encapsulate seams and fastener heads on metal roofing systems with minimal sag. The 100% solids, solvent-free formulation is isocyanate-free and exhibits less moisture sensitivity than standard polyurethanes while maintaining high tensile strength and elongation.

This sealant is commonly used for sealing metal roof seams, fasteners, gutters, and roof penetrations. It conforms to the shape it is applied to, hangs vertically with minimal slumping, and adheres to a wide range of roofing substrates including metal, asphalt, EPDM, PVC, aged TPO, concrete, and brick. 838 MS may be poured, extruded, or brushed depending on application requirements.

Key features:

• Hybrid moisture-cure elastomer sealant
• 100% solids, solvent-free and isocyanate-free
• Designed to encapsulate metal roof seams and fasteners
• Minimal sag with strong vertical hang
• High tensile strength and elongation
• Adheres to metal, asphalt, EPDM, PVC, aged TPO, concrete, and brick
• Can be poured, extruded, or brushed

Brand: 838 Coatings
Product type: Hybrid moisture-cure elastomer sealant
Product line: 838 MS (Multi-Purpose Sealant)
Packaging type: Sausage
Size: 20 oz
Total solids: 100% by volume
Application temperature: 42°F to 120°F (air and substrate)
Drying time: Tack-free approximately 1.5 hours (75°F, 50% RH)
VOC: < 1 g/L
Application method: Extrusion, pour, or brush
Use: Professional roofing and construction applications

Does it need perfect weather to apply?

No. This sealant can be applied in wet conditions and even underwater if needed. It cures faster than many comparable products, typically within 1–2 hours depending on conditions. As with any sealant, extreme conditions can affect working time, but it’s designed to perform when the job can’t wait on perfect weather.

Will this crack or get brittle over time?

No. Once cured, the sealant stays flexible, which helps it move with the roof and handle normal expansion and contraction.

Do I need fabric when applying this sealant?

No. Fabric is not required for standard applications. In most cases, the sealant can be applied directly to the surface and tooled as needed. Some installers may choose to reinforce certain details based on job conditions, but it’s not a requirement for use.