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Hollow Glass Microsphere
ITM17552, ITM17553

3M™ Glass Bubbles S28HS are hollow glass spheres with a typical density of 0.28 g/cc and an isostatic crush strength of 3,000 psi.


  • Decreases weight and increases buoyancy for lower density in finished parts
  • Versatile use – adaptable to a variety of production processes including high shear liquid mixing systems
  • Delivers stable voids for reduced thermal conductivity and dielectric constant in syntactic foams
  • Provides excellent water and oil resistance for use in underwater applications
  • Very good strength-to-density ratio for use in a variety of construction and oil and gas applications
  • Good choice for dead-pressing resistant emulsion explosives

What are 3M™ Glass Bubbles? 

Our 3M™ Glass Bubbles S28HS (PDF, 96.2 Kb) are engineered hollow glass spheres made from water-resistant and chemically-stable soda-lime borosilicate glass. Like all 3M™ Glass Bubbles, our S28HS 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. 

Superb Strength-to-Weight Ratio 

The benefits don't end there; although these hollow spheres have thin walls, they have an impressive isostatic crush strength of 3,000 psi, making them suitable for a number of buoyancy applications, including additives in buoys and moorings. At 3,000 psi, S28HS bubbles have a targeted fractional survival rate of 90% for consistent performance and greater survivability. 

Notably, 3M™ Glass Bubbles S28HS are lower density 3,000 psi glass bubbles that offer significantly less weight, for better thermal conductivity at a given depth rating. These glass bubbles provide significantly lower density for better thermal conductivity at a given depth rating compared with S35 glass bubbles. 

Airless Spray Coatings

glass bubbles S28HS bubbles can be used in many applications. One area where they excel is in airless spray coatings. Here's how it works — an airless spray pumps a liquid that shoots through a nozzle. When bubbles are added to a coating, they have to survive this process and remain intact, meaning it's important to pick bubbles on the basis of strength. Our bubbles offer sufficient strength at a minimal density. 

In general most of airless spray equipment is in the 2,500-4,000 psi range. Our S28HS may work well for airless spray depending upon the formulation. It's not just the fact that it has a 3,000 psi rating, this bubble has an average diameter of 30 microns, and 0.28 g/cc density. This unique combination of strength, overall particle size and density means this bubble may be well suited for airless spray coatings. 

Other applications include:

  • Paints and coatings
  • Rubber and plastic
  • Insulation and buoyancy
  • Thermal insulation
  • Wet pipe flowline insulation