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Hollow Glass Microsphere
ITM11120, ITM11468, ITM11469, ITM19426, ITM19638

3M™ Glass Bubbles K1 are hollow glass microspheres that are ideal for a number of applications including – shallow (e.g. up to 2,000 feet of sea water) water flotation devices and lightweight wall repair compound. These low-cost, economical bubbles have a very low typical density (0.125 g/cc) and an isostatic crush strength of 250 psi.


  • Decreases density and increases buoyancy to help improve efficiency and may lower material costs
  • Provides excellent water and oil resistance for use in underwater applications
  • Stable voids for low thermal conductivity and reduced dielectric constant
  • Versatile use – adaptable to a variety of production processes
  • Provides buoyancy in syntactic foam compositions
  • Additive can easily be sanded in lightweight wall repair compounds


What are 3M Glass Bubbles? 3M™ Glass Bubbles K1 are hollow glass spheres with a typical density of 0.125 g/cc, offering good strength-to-density ratio. These general purpose spheres are designed for use in a variety of applications, including oil and gas drilling operations and as an additive in lightweight wall repair compounds. Notably, our K1 glass bubbles have low thermal conductivity, helping coatings achieve very good thermal insulation performance while minimizing heat flow.

The general purpose K Series glass bubbles are the most versatile and economical 3M™ Glass Bubbles. Our 3M glass bubbles are engineered hollow glass spheres made from water-resistant and chemically-stable soda-lime borosilicate glass. Like all 3M glass bubbles, our K1 glass bubbles are water and oil resistant, providing better utility in underwater applications. Additionally, they are non-combustible and non-porous, so they do not absorb resin; and their low alkalinity makes this product compatible with most resins while providing a stable viscosity and a long shelf life.

3M glass bubbles are a superior alternative to many conventional fillers and additives such as silicas, calcium carbonate, talc, clay and other materials used in demanding applications. Our low-density spheres are used in a wide range of industries to reduce part weight, lower costs and enhance product properties — making them more reliable and affordable than many alternatives such as cenospheres and perlite.

Strength-to-Weight Ratio

The benefits don't end there; although these hollow spheres have thin walls, they have an isostatic crush strength of 250 psi, making them suitable for a number of buoyancy applications, including additives in buoys and shallow water buoyancy applications (e.g. up to 2,000 feet of sea water). K1 glass bubbles have a fractional survival rate of 80% or more, at 250 psi for consistent performance in highly filled resin systems.

The spherical shape of these bubbles offers a number of additional benefits, including: higher filler loading, lower viscosity/improved flow and reduced shrinkage and warpage. Higher filler loading offers the potential for lower costs. Adding to this product's versatility is its ability to be easily blended into compounds — making it adaptable to a variety of production processes including spraying, casting and molding.

Lightweight Wall Repair Compound

Clearly our 3M™ Glass Bubbles K1 (PDF, 82.47 Kb) can be used in a variety of applications. One popular use is in lightweight wall repair compounds where they provide volume and resin displacement without the weight. When using a wall repair compound, it's important to fill the hole without adding unnecessary weight to the wall. Older compounds sag under their own weight, but our small, strong and lightweight bubbles take up the majority of the volume without adversely affecting the aesthetic or structural quality of repaired walls. Additionally, the bubbles can easily be sanded to form a flush surface, and can be painted if needed. All in all, these bubbles give users great value on the dollar.

Other Applications Include:

  • Bowling balls
  • Cast polyester
  • Paints and coatings
  • Drill riser buoyancy modules
  • Caulk
  • Adhesives
  • Emulsion explosives
  • Polyester putty
  • Potting compounds
  • Tooling boards
  • Spackling compound