How Glass Fibers Are Spun for Insulation
A 1933 invention by Games Slayter that describes the process of melting glass and blasting it into fine, flexible fibers to create insulation.
Original patent title: “Method and apparatus for making glass wool”
A 1933 invention by Games Slayter that describes the process of melting glass and blasting it into fine, flexible fibers to create insulation. Granted to Owens Illinois Glass Co in 1938 with 22 forward citations, and it is now in the public domain.
Key facts
Coverage
What does this patent actually cover?
The patent details a method for producing glass wool by melting glass and using high-velocity steam or air jets to attenuate the molten material into thin, flexible fibers. These fibers are then collected to form a mat or batt of insulating material. By controlling the temperature of the glass and the pressure of the gas blast, the process creates a lightweight, fire-resistant, and thermally efficient material that traps air within the fiber matrix.
The gap
What does this patent NOT cover?
- Does not cover the chemical composition of the glass itself.
- Does not cover the use of centrifugal force or spinning disks to form fibers.
- Does not cover the application of binding resins to hold the fibers together.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The invention recognized that high-velocity gas jets could stretch molten glass into fibers thin enough to be flexible, rather than brittle, by rapidly cooling them during the attenuation process.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Residential attic insulation batts
Commercial building HVAC duct lining
Industrial pipe insulation
Why it matters
The bigger picture
This technology enabled the mass production of fiberglass insulation, which transformed the construction industry by providing a cheap, durable, and fire-safe way to insulate homes. It turned a laboratory curiosity into a standard building material used in almost every modern structure.
Filed
November 11, 1933
Granted
October 11, 1938
Market context
Who's building on this
Companies in this space
Owens Corning, the successor to the original research efforts, remains a global leader in fiberglass production. Modern manufacturers continue to refine the energy efficiency and fiber diameter control of this basic thermal attenuation process.
Market impact
This patent laid the foundation for the modern fiberglass insulation industry. It allowed for the transition from expensive, labor-intensive production to automated, high-volume manufacturing, making energy-efficient housing accessible to the general public.
Claim 1 — Plain English
What this patent covers
The patent details a method for producing glass wool by melting glass and using high-velocity steam or air jets to attenuate the molten material into thin, flexible fibers. These fibers are then collected to form a mat or batt of insulating material. By controlling the temperature of the glass and the pressure of the gas blast, the process creates a lightweight, fire-resistant, and thermally efficient material that traps air within the fiber matrix.
The clever bit
The invention recognized that high-velocity gas jets could stretch molten glass into fibers thin enough to be flexible, rather than brittle, by rapidly cooling them during the attenuation process.
What it does not cover
- Does not cover the chemical composition of the glass itself.
- Does not cover the use of centrifugal force or spinning disks to form fibers.
- Does not cover the application of binding resins to hold the fibers together.
Patent Journey
From filing to expiry
PatentBrief Score
Impact Score
Early stage
Citation count
27/40
Moderately cited
Claim breadth
0/20
Narrow claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$22K – $69K
Midpoint $43K · expired or expiring · industry ×2.4
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Concepts involved
Citations
Patent lineage
Cite this patent
Games, S. (1938). How Glass Fibers Are Spun for Insulation (U.S. Patent No. 2,133,235). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/2133235/fiberglass-glass-wool-slayter
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Glass Fibers Are Spun for Insulation cover?
A 1933 invention by Games Slayter that describes the process of melting glass and blasting it into fine, flexible fibers to create insulation.
Who owns patent US 2133235?
Owens Illinois Glass Co owns this patent, granted in 1938.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 2133235 cited by?
This patent has been cited by 22 later patents that build on its ideas.
What problem does this patent solve?
This technology enabled the mass production of fiberglass insulation, which transformed the construction industry by providing a cheap, durable, and fire-safe way to insulate homes. It turned a laboratory curiosity into a standard building material used in almost every modern structure.
What does this patent NOT cover?
Does not cover the chemical composition of the glass itself.
Patent monitoring