Edgetherm® JS-780

A 100% solids sealant based on polyisobutylene polymer formulated to impart reinforcement, resist degradation from ultraviolet light, and provide low moisture permeability.


  • Excellent adhesion to glass and metal through a wide temperature range.
  • Features an extremely low moisture vapor transmission rate.
  • Extremely low argon permeance.
  • Non-fogging (100% solids).
  • Consistent quality.
  • Retains flexibility through a wide temperature range to compensate for thermal movement of the insulating glass unit.
  • Resists degradation from ultraviolet light and oxidation.
  • Available in black.
  • JS-780 is available in pre-extruded strands for applying to spacer bars and in bulk (slug form) for application by various type extruders.
    • Pre-extruded Strands: 1/8”, 3/32”, 1/16” diameter
    • Slugs: 7.5”D x 9.5” H (15 lb/7 kg)
      • 4.5”D x 7”H (4 lb/2 kg)
      • 9.5”D x 10.5”H (27 lb/12kg)
    • Drums: Steel 55 gallon

JS-780 is used as the primary seal on insulating glass units while providing the main moisture vapor seal between the glass and metal spacer. JS-780 must be used with a secondary seal designed to provide structural strength.

Performance Norm
Moisture Vapor Transmission Rate
0.13/m²/d, 0.060” fi lm, 100° F, 100% RH
ASTM F 1249
Volatile Fogging
ASTM E 2189
Low Temperature Flexibility
Passes - 40° F, 1/2” mandrel
ASTM D 3111
Weight per Gallon (Specific Gravity)
Black: 8.75 lb/U.S. gal (1.05 g/cc)
Tensile Adhesion Strength
40-50 psi
TST 680B
Argon Permeance &

3 cc/100 in.²/d, 0.31” fi lm
120 cc mil/100 in.²/d
ASTM D 1434
Note: The foregoing information is published as general information only. The listed properties and performance characteristics are approximate value and are not part of the product specifi cation.