19AF Flashing Cement

Karnak #19AF Flashing Cement is a scientifically compounded composition of selected asphalts, mineral fibers, and refined solvents that are manufactured to a heavy consistency for application by trowel to provide a durable, elastic coating of excellent adhesion and high resistance to water and weathering. This product dries to a tough, flexible, waterproof and corrosion proof coating which gives excellent performance over wide ranges of temperature and weather conditions. Karnak #19AF Flashing Cement is available in 2 consistencies: Summer and Winter.


1. Consistency: A smooth, heavy trowel consistency which will readily spread on and adhere to vertical and horizontal surfaces without sagging.
2. Character of Dried Film: Uniform, excellent adhesion to masonry, steel, cured concrete, shingles, asphalt roofing and a variety of other surfaces.
3. The dried film retains its flexibility and ductility so that the coating will resist extreme variations in temperature and weather.
4. Has excellent resistance to flow at high temperatures when used on a vertical surface.


Karnak #19AF Flashing Cement is a general purpose cement for repairing leaks in shingles, concrete, metal or asphalt roofs, flashings on walls, chimneys, flues, downspouts and cornices. It is excellent for sealing cracks in concrete and brick, as a joint filler for precast roof slabs and for general purpose use in maintenance of exposed buildings and structures.


  • Federal Specification SS-C-153 Type I (AF)
  • ASTM D-4586 Type I


All surfaces should be clean, dry and free from oil or grease, dust, dirt, loose paint or other foreign matter.


Spread Karnak #19AF Flashing Cement to an average thickness of 1/8" (approximately 8 gallons per square) and press tightly into joints, seams or cracks. To repair large cracks, breaks and blisters:
  • Spread Karnak #19AF Flashing Cement over the damaged area.
  • Embed Karnak Cotton, Glass or PolyMat Membrane reinforcement.
  • Apply another coat of Karnak #19AF Flashing Cement over the entire patch.


Tools and other equipment should be thoroughly cleaned with mineral spirits, taking necessary precautions when handling combustible materials.


Do not use near open flame. Avoid breathing solvent fumes and prolonged contact with skin. Do not take internally. If swallowed, do not induce vomiting. Call a physician immediately. Keep out of reach of children. Keep container covered when not in use. Do not thin. Dispose of in an environmentally safe manner.


Available in 5 gallon pails, 3 gallon buckets and 1 gallon cans.

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Kanopy Reflective Roof Maintenance Solutions
  • Reduce Energy Use
  • Lowers Peak Energy Use, reducing energy costs year-round
  • Helps the environment, reduces "Heat Island Effect"
  • Extend the life of the roof
  • Reduces waste. Helps avoid roof tear-off.
  • Economic compared to roof replacement
  • Eliminates interior building operation disruption