Hollow Glass Microspheres
ULTRA-LOW DENSITY · LIGHTWEIGHT SYNTACTICS

3M™ GLASS BUBBLES
K1

Designed for applications demanding extreme weight reduction. K1 features the lowest true density in the 3M™ K-series family, ideal for polyester putty, sound deadening coatings, gypsum plaster, thermal insulation exterior coatings, and sealants.

True Density: 0.125 g/cm³ Crush Strength: 250 psi (1.7 MPa) Target: Putties, Plasters, Coatings & Sealants

Ultra-Low Density Micro-Spherical Additive Engineering

3M™ Glass Bubbles K1 engineered additives consist of high-strength, water-insoluble, chemically stable soda-lime-borosilicate hollow glass microspheres designed for applications demanding maximum weight reduction and volumetric yield expansion. Featuring an ultra-low true density of 0.125 g/cm³ and an isostatic crush strength of 250 psi (1.7 MPa), K1 represents the lowest-density variant within the 3M™ K-series lineup. These completely intact, smooth, spherical hollow bubbles act as microscopic ball-bearings within paste and liquid formulations, dramatically improving sanding ease in polyester putty, damping acoustic vibration in sound deadening coatings, increasing bag yield in gypsum plaster, reducing thermal conductivity in thermal insulation exterior coatings, and eliminating shrinkage and sagging in high-build elastomeric sealants.

3M™ Glass Bubbles K1 is specifically optimized for low-shear compounding processes where maximum density reduction and volumetric yield take priority over high-pressure extrusion.

CORE TECHNICAL SPECIFICATIONS

3M™ Glass Bubbles K1 Performance Metrics

Review key physical parameters, density limits, and target matrix compatibility for 3M™ Glass Bubbles Grade K1 below.

True Density

0.125 g/cm³

Achieves the lowest density in the K-series family, delivering maximum volumetric yield expansion per kilogram.

Isostatic Crush Strength

250 psi (1.7 MPa)

Provides reliable structural sphere integrity during low-stress mixing, troweling, and ambient compounding.

Target Applications

Putties, Plasters, Coatings & Sealants

Engineered for polyester putty, sound deadening coatings, gypsum plaster, thermal insulation exterior coatings, and sealants.

Key Functional Benefits

3M™ Glass Bubbles K1 provides a unique combination of extreme light-weighting, acoustic damping, low thermal conductivity, and easy workability.

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Maximum Density Reduction

At 0.125 g/cm³, K1 cuts mass by up to 30% in polyester body fillers, sealants, and gypsum plasters.

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Thermal Insulation Performance

Hollow air-filled borosilicate glass cells significantly reduce heat transfer in exterior thermal insulation wall coatings.

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Superior Sandability & Finishing

In lightweight polyester putties, spherical glass bubbles fracture cleanly under sandpaper, reducing dust and labor time.

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Acoustic & Sound Damping

Disrupts sound wave propagation within liquid and sprayable sound deadening coatings for automotive and industrial panels.

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Shrinkage & Sag Control

Prevents volume shrinkage and vertical sag in thick elastomeric joint sealants, caulks, and gypsum plaster fills.

High Volumetric Yield

Replaces dense mineral fillers on a volume-for-volume basis, expanding bucket and bag yield significantly.

Primary Target Applications

Specific deployment across body fillers, acoustic barriers, gypsum mortars, exterior facade systems, and architectural sealants.

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Polyester Putty & Body Fillers

Substantially lowers putty density for lightweight automotive and marine repairs, dramatically enhancing trowel spreadability and fast, effortless sanding.

Polyester Putty Automotive Fillers Easy Sandability Body Fillers & Putty
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Sound Deadening Coatings

Incorporated into sprayable acoustic coatings and liquid-applied sound deadeners (LASD) to absorb structural resonance and vibration in machinery and transport cabins.

Sound Deadening Vibration Damping LASD Coatings Acoustic Coatings
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Gypsum Plaster & Wall Renders

Lowers deadweight in gypsum plasters, machine-applied wall renders, and joint compounds while improving coverage per 25kg bag and reducing troweling fatigue.

Gypsum Plaster Joint Compounds Bag Yield Expansion Gypsum Systems
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Thermal Insulation Exterior Coatings

Formulated into cool-roof paints, elastomeric facade coatings, and thermal barrier paints to reduce heat ingress, lower k-values, and increase solar reflectance.

Thermal Insulation Exterior Coatings Cool Roof Paints Exterior Coatings
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Architectural & Industrial Sealants

Provides non-sag vertical hold, zero cure shrinkage, and low-density properties in polyurethane, silicone, acrylic, and MS polymer joint sealants.

Sealants PU & MS Polymers Zero Shrinkage Sealants & Caulks
3M™ Glass Bubbles K1 Specification Matrix
Target Application Formulation Function Key Technical Benefit Recommended Addition Level
Polyester Putty Density & Sanding Modifier Effortless sanding, dust reduction & lightweighting 10% – 25% by volume
Sound Deadening Coatings Acoustic & Density Attenuator Resonance absorption & sprayable viscosity control 8% – 20% by volume
Gypsum Plaster Lightweight Fill & Yield Booster Expands bag yield & lowers wall structural load 5% – 15% by weight
Thermal Insulation Exterior Coatings Solar Reflectance & Thermal Barrier Reduces thermal conductivity & roof solar gain 10% – 30% by volume
Sealants & Caulks Anti-Shrink & Thixotropic Filler Zero volumetric shrinkage & high vertical hold 5% – 20% by volume
Compounding & Shear Management

Due to its 250 psi crush strength, 3M™ Glass Bubbles K1 should be added toward the end of low-shear mixing cycles to maintain 100% spherical integrity.

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Low-Shear Incorporation

Introduce K1 during the final let-down stage using ribbon blenders, planetary mixers, or slow-speed paddle agitators.

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Moisture-Proof Storage

Store in original sealed poly-lined bags in a dry, cool warehouse to prevent moisture clumping and dust dispersion.

Information Desk

Frequently Asked
Questions (FAQ)

Get quick, technically vetted answers regarding 3M™ Glass Bubbles K1 density, strength, compounding, and target formulations.

1. What makes 3M™ Glass Bubbles K1 unique compared to traditional mineral fillers?
3M™ Glass Bubbles K1 features an ultra-low true density of 0.125 g/cm³, making it significantly lighter than calcium carbonate, talc, or silica. Unlike ground irregular fillers, K1 microspheres possess a smooth, perfectly rounded geometry that creates a "ball-bearing" effect, lowering liquid viscosity while dramatically reducing finished product weight.
2. Why is Grade K1 preferred in Polyester Putty and Body Fillers?
In polyester putties, Grade K1 reduces paste density down to 0.8–1.0 g/cm³. The spherical shape allows the putty to spread effortlessly under a trowel and fractures cleanly under sandpaper, enabling faster, smoother sanding with fewer pinhole defects and reduced physical labor.
3. How do K1 microspheres function in Sound Deadening Coatings?
When added to liquid-applied sound deadeners (LASD) or sprayable acoustic coatings, hollow glass spheres introduce microscopic cell interfaces into the polymer matrix. These interfaces scatter acoustic wave energy, damping structural resonance, reducing vibration noise, and trimming vehicle body deadweight.
4. What advantages does Grade K1 bring to Gypsum Plaster and Wall Renders?
Adding K1 glass bubbles to gypsum plaster formulations expands bag volume yield, allowing workers to cover a larger wall surface area per kilogram of dry mix. It also lowers the structural weight load on interior partition walls and makes hand-troweling or machine spraying much easier.
5. How does Grade K1 enhance Thermal Insulation Exterior Coatings?
3M™ Glass Bubbles K1 encapsulate a hollow air/vacuum cavity inside an inert borosilicate glass shell. When formulated into cool-roof coatings or exterior wall paints, these microspheres reflect solar radiation and lower thermal conductivity, helping reduce building interior heat gain.
6. How do glass bubbles eliminate shrinkage and sag in Sealants and Caulks?
Since glass spheres are rigid, non-porous structures, they do not absorb liquid solvents or monomers. In joint sealants and caulks, replacing volatile solvents or heavy mineral fillers with K1 eliminates volume shrinkage during curing and provides excellent thixotropic sag resistance in thick vertical joints.
7. What is the isostatic crush strength of K1 and how should it be mixed?
Grade K1 has an isostatic crush strength of 250 psi (1.7 MPa). Because it is engineered for ultra-low density rather than high-pressure survival, it should be incorporated near the end of low-shear batch mixing using ribbon blenders, slow paddle agitators, or planetary mixers to prevent sphere breakage.
8. Are 3M™ Glass Bubbles K1 water-soluble or chemically reactive?
No. Grade K1 is composed of high-purity soda-lime-borosilicate glass that is 100% water-insoluble, non-combustible, non-porous, and chemically inert across waterborne, solventborne, epoxy, polyester, polyurethane, and cementitious systems.

Geocon Group — 3M Specialty Glass Bubbles Division
Geocon Group supplies 3M™ Glass Bubbles K1, K15, K20, K25, K37, and high-strength iM series microspheres across India. We provide laboratory trial assistance, density matching, and sample dispatch from our corporate hub in Navi Mumbai and R&D lab in Bhandup.

SECTOR MATRIX OVERVIEW

3M™ Glass Bubbles K1 Target Applications at a Glance

Discover how 3M™ Glass Bubbles K1 enables ultra-low density, thermal insulation, acoustic damping, and smooth sanding across key application fields.

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Putties

Polyester Body Putty

K1 microspheres reducing body filler mass while enabling easy, fast sanding with minimal pinholes.

Lightweight Putty Easy Sanding
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Plasters

Gypsum Plaster & Renders

Expanding bag yield and reducing structural deadweight on wall partitions and machine-applied plasters.

Gypsum Plaster High Yield
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Coatings & Seals

Thermal Coatings & Sealants

Enhancing thermal insulation in exterior wall paints, sound deadening, and sag-free joint sealants.

Thermal Exterior Sealants
Procure

3M™ Glass Bubbles K1

Connect with our Navi Mumbai technical sales desk to request evaluation sample kits, Technical Data Sheets (TDS), or pricing for 3M™ Glass Bubbles Grade K1 in Polyester Putty, Gypsum Plaster, Thermal Coatings, or Sealants.

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