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3M™ Hollow Glass Microspheres – Grade K-15 are low-density, thin-walled soda-lime borosilicate glass microspheres specifically suited for lightweight, thermally efficient roofing systems. In roofing applications, K-15 microspheres help formulators achieve reduced coating density, improved thermal insulation, and enhanced solar heat reflectance without compromising application properties.
When incorporated into heat-reflective roof coatings, elastomeric membranes, and lightweight roof repair grouts, K-15 microspheres create stable microscopic air voids that interrupt heat transfer, reduce dead load on roofs, and improve ease of application—making them ideal for both new construction and refurbishment projects.
Zeolite Silver Antimicrobial Powder/ Ag-Zeolite Powder
1318-02-1
215-283-8
3824.99.00
not classified as dangerous goods
2.1–2.3 g/cm³
4–5
0.1%
K-15 microspheres are widely used in cool roof coatings and solar-reflective membranes.
Functional role:
Reduce coating density and thermal conductivity
Improve reflectivity efficiency by stabilizing pigment orientation
Enhance coating thickness build without excessive weight
Typical systems:
Acrylic and elastomeric roof coatings
PU and epoxy roof top coats
White and light-colored heat-reflective coatings
In cementitious and polymer-modified grouts, K-15 microspheres act as lightweight fillers, replacing heavier aggregates.
Functional role:
Significant dead-load reduction on slabs and decks
Improved workability and pumpability
Reduced shrinkage stress in thick sections
Typical systems:
Roof screeds and slope-forming mortars
Crack-filling and leveling grouts
Lightweight repair mortars for RCC roofs
Elastomeric waterproofing membranes
Thermal-insulating roof coatings
Roof protection layers under solar panels
| Property | Typical Value |
|---|---|
| Composition | Soda-lime borosilicate glass |
| Particle morphology | Hollow spheres |
| True density | ~0.15 g/cc |
| Bulk density | ~0.09 g/cc |
| Crush strength (90% survival) | ~250 psi |
| Average particle size | ~50 microns |
| Thermal conductivity | Very low (air-filled structure) |
| Combustibility | Non-combustible |
| Color | White |
Entrapped air inside microspheres reduces heat transfer through roof coatings and grouts.
Enables thick, high-build coatings and lightweight mortars without increasing structural load.
Supports better pigment dispersion and stable reflective surfaces in white roof coatings.
Spherical shape improves spread, leveling, and sprayability.
Lightweight structure reduces internal stresses in roof mortars and screeds.
Inorganic glass structure resists UV, moisture, and temperature cycling.
Exact loading depends on coating thickness, thermal target, and mechanical requirements.
2 %– 5% by volume of total formulation
Higher loadings enable thicker, more insulating films without sagging.
3%– 5% replacement of conventional fillers/aggregates (by volume)
Optimized for weight reduction and thermal performance.
Refer to SDS for detailed safety guidance.