Heat-expandable and fire-resistant sheet

TOMBO™ No. 6760-A


VERMOFLEX is a heat-expanding fireproof sheet that is made by mixing a heat-expandable inorganic material and small amounts of organic and inorganic binders with alkali earth silicate (AES) wool, and then manufacturing it into a sheet form. Its thickness expands by about three-fold when heated (when heated without a load).

Product Category

Thermal Insulation MaterialUp to 600°CUp to 1500℃


Iron & Non-Ferrous MetalsAluminum Casting & Machining


Stable expansion properties
Excellent handling
Can be cut easily with a cutter
Excellent thermal insulation
High heat and shock resistance

Before expansion

After expansion


Heat sealing materials
Heat-resistant buffer

Physical property values

Item Unit Physical property values
Maximum working temperature °C 800
Density Room temperature
After heating at 850°C for 30 mins
kg/m3 500
Foaming factor After heating at 850°C for 30 mins About 3 times
Temperature when starting to expand °C 400
Significant expansion temperature °C 540
Ignition loss After heating at 850°C for 30 mins 16
Thermal conductivity 25°C (before expansion)
800°C (after expansion)
W/(m・K) 0.05
*The values in the table are our actual measurement values. They are not standard values.

Standard dimensions

Unit: (mm)
Standard dimensions 1, 000×1, 000
Standard thickness 2.0, 3.0, 4.0


  • TOMBO is a registered trademark or trademark of NICHIAS Corporation.
  • Name of products with "®" are registered trademarks of NICHIAS Corporation.
  • Name of products with "™" are trademarks of NICHIAS Corporation.