Karnak - 502MS Karna-Flex Sealant, 3 gallon

Karnak 502MS Karna‑Flex Sealant is a high-performance, rubberized mastic specifically engineered for sealing critical areas across a wide range of roof systems. Packaged in a 3-gallon pail, this single-component formula offers excellent workability and delivers a watertight, elastomeric seal that adapts to structural movement. It adheres exceptionally well to both dry and damp surfaces, making it ideal for year-round repairs in real-world jobsite conditions. Whether you're reinforcing seams, patching flashings, or sealing around penetrations, Karna-Flex provides lasting flexibility and resistance to water, UV, and temperature extremes—ensuring repairs stay sealed through seasonal shifts and environmental exposure.

Key Features

• 3-gallon pail size designed for professional use and larger repair projects
• Elastomeric rubber formulation provides long-lasting flexibility and crack resistance
• One-component, ready-to-use sealant—no mixing required
• Superior adhesion across a wide range of roofing substrates
• Remains flexible even at low temperatures

Packaging: 3-gallon pail; 70 Pails/Pallet (also available in 30-oz caulking tubes)

Application temperature: 40 °F to 120 °F

Coverage rates: 4–8 gallons per 100 sq ft at 1/16″–1/8″ thickness

Reinforced seam coverage (with fabric):

• 1/16″: ~25 linear ft (4″ fabric), ~18 linear ft (6″ fabric) per gallon
• 1/8″: ~12 linear ft (4″), ~9 linear ft (6″) per gallon

Fastener coverage: approx. 250 fasteners per gallon

Weight per gallon: ~9.5 lb

Elongation: up to ~900%

Service temperature: 15 °F to 180 °F

Low temperature flexibility: down to –40 °F

Color options: White, Black, Gray (white not recommended over asphalt surfaces)

* This item is hazmat *

• Prepare the surface by removing dirt, dust, oil, and excess water. Product can bond to damp areas, but cleaner surfaces enhance adhesion.
• Apply by brush directly from the 3-gallon pail at a thickness of 1/16″ to 1/8″.
• For seams or larger cracks, embed reinforcing fabric into the wet sealant and cover with an additional coat.
• For metal fasteners or pinpoints, apply a swirl of material directly over each location.
• Smooth the sealant for uniform adhesion and appearance.
• Allow the product to cure fully (approx. 24 hours) before top-coating or water exposure.
• Clean tools with mineral spirits and work in a ventilated space, away from open flames.

Q: What surfaces can this product be applied to?
A: It bonds to asphalt BUR, modified bitumen, concrete, metal, spray foam, aged EPDM, TPO, and PVC.

Q: Can it be applied to wet areas?
A: Yes—it adheres to wet or dry substrates, though dry and clean conditions give the best results.

Q: How much coverage will a 3-gallon pail provide?
A: At 1/16″–1/8″ thickness, coverage averages 4–8 gallons per 100 sq ft.

Q: Do seams or cracks require reinforcement?
A: Yes—embed fabric reinforcement in seams or large cracks, then apply a second coat.

Q: Can the white version be used on asphalt?
A: No—white should not be applied to asphalt substrates; use black instead.