Metal Silicone

Metal Silicone is a Kool Coats coating system for restoring existing metal roofs with a silicone finish. It belongs to the Metal family and is listed for the USA market. The assembly combines a rust-converting primer, a silicone mastic for joints and fasteners, and a high solids silicone roof coating.

Profiled metal panels shed water across side laps and end laps. Exposed-fastener roofs, including R-panel roofs, also have washers and screws that are treated as part of the system. Sound panels stay in place while loose fasteners, open joints and localized corrosion are repaired.

The system is one of the metal roof coating assemblies in the Kool Coats range, and its silicone chemistry is the counterpart to the acrylic metal system.

The system draws on three Kool Coats products.

• P-309 Rust Converting Primer for rusted areas of metal.
• KF-460 KoolFlex Silicone Mastic for seams, fasteners and repairs.
• KF-600 KoolFlex High Solids Silicone as the finish coating.

P-309 has an acrylic carrier and chemically converts red hematite rust into stable black magnetite, forming a hard, coatable surface without mechanical removal. Silicone coatings can be applied directly once conversion is complete and the surface is dry. The product is not a standalone coating and is topcoated as part of a complete system.

It is applied to metal showing active red rust. Loose rust, scale, flaking paint, grease and oil are removed by wire brushing, grinding or power washing. Sound, tightly adhered rust may remain, since removal to bare metal is not necessary. Surfaces are clean, dry and free of standing water. It is not applied over galvanized, painted or non-rusted metal.

Application is by brush, roller or airless spray between 50 F and 120 F and rising, with no rain, condensation or freezing during cure. Converted areas darken to black or deep gray in about 24 hours at 77 F and 50% relative humidity. Severely deteriorated or structurally compromised metal may need repair or replacement and is not warrantable solely by rust conversion.

• Coverage: 0.25 to 0.5 gallon at 4 mils wet film thickness per 100 sq ft
• Weight per gallon: 8.8 lbs; viscosity: 65 KU
• Solids by weight: 48% nominal; pH: 4 nominal
• VOC: less than 50 g/L
• Color: clear white
• Packaging: tote, drum, 5 gallon, 1 gallon and 12 x 1 quart
• Shelf life: two years from date of manufacture

KoolFlex 460 is a moisture cure, 100% silicone mastic for sealing and repairing roofs, flashings, walls, masonry, and metal roof seams and fasteners. It is applied by trowel or brush on vertical or horizontal surfaces, in layers from 1/8 inch to 1/4 inch, with a maximum build of 1/4 inch. Material is spread 2 to 4 inches beyond cracks to feather the edges.

Listed adhesion includes metals and Kynar, along with concrete, masonry, vinyl, fiber cement, polyurethane foam, EPDM, aged acrylic coatings, granular cap sheet and wood. It can go on wet and underwater surfaces, and a primer may be needed.

• Coverage: 24 sq ft per gallon at 1/16 inch; 12 sq ft per gallon at 1/8 inch
• Solids by volume: 60%; by weight: 53%; weight per gallon: 11.8 lbs
• Tensile strength: 300 psi; elongation: 250% nominal
• Tear resistance: 82 lbs/in; hardness: 70 Shore A
• Tack free in 1 to 3 hours; fully cured in 24 hours
• Application temperature: 35 F to 120 F in the application text; 50 F to 100 F in the properties table
• Service temperature of the cured film: 15 F to 180 F
• Supplied in 5 gallon containers; opened containers are used up as soon as possible and skin is removed if it forms

KoolFlex 600 is a single component, moisture cure, 95% volume solids elastomeric silicone roof coating, and it is marked ASTM D6694 compliant. Metal is one of its listed substrates, with masonry, concrete, vertical walls, single-ply membranes, modified bitumen, built-up roofing and sprayed polyurethane foam. Standard colors are white, tan and gray.

The rate for most substrates is 1.5 gallons per 100 sq ft, equal to 17 mils wet film, with 20 mils dry coat thickness listed. Spray equipment is a high-pressure airless unit giving at least 3500 psi at the gun and at least 3 gallons per minute, with BUNA-N jacketed hoses of at least 3/4 inch inside diameter and a reverse-a-clean tip with a .030 minimum orifice. Rolling uses a medium nap roller.

• Initial elongation: 279% at 73 F and 248% at 0 F
• Aged elongation after 5,000 hours: 194% at 73 F and 229% at 0 F
• Tear strength, Die C: 30 lbf/in
• Permeance: 6.3 US perms
• Low temperature mandrel bend: pass at -15 F
• 5,000 hours accelerated weathering: pass
• Initial SRI: 109
• Rain-safe in 1 hour; tack free in 1 to 2 hours; recoat after 24 hours; final cure 30 hours
• VOC: less than 50 g/L

Panels are cleaned and loose coatings removed. Damaged metal is repaired, fasteners are secured, and seams, flashings and penetrations are repaired and sealed before coating. Low areas that hold water are repaired. Chemical cleaning, power washing or priming may be needed on some substrates.

Mastic and primer work is done above 40 F and rising with humidity under 90% and no rain for 48 hours. The silicone coating is not applied below 40 F or when rain is expected within four hours. It is not thinned, and equipment is cleaned with 100% mineral spirits.

KoolFlex 600 is supplied in 50 gallon and 5 gallon containers with a 24-month shelf life, stored between 40 F and 85 F. Available warranties include Full System Limited Warranties from 5 to 20 years. A 10 to 20 year Material Warranty, with a Labor and Material Warranty available for a fee, and states it is non-transferable and given solely to the original purchaser.