How to Make Silly Putty Using Silicone and Zinc
A 1944 chemical process for turning liquid silicone oil into a bouncy, stretchable, putty-like material by adding boron compounds and zinc hydroxide.
Original patent title: “Process for making puttylike elastic plastic, siloxane derivative composition containing zinc hydroxide”
A 1944 chemical process for turning liquid silicone oil into a bouncy, stretchable, putty-like material by adding boron compounds and zinc hydroxide. Granted to General Electric Co in 1951 with 2 claims and 80 forward citations, and it is now in the public domain.
Coverage
What does this patent actually cover?
The patent describes a three-step chemical process to create a unique elastic material. First, you heat liquid dimethylsiloxane with a boron-based catalyst, such as boric acid or borax, until it transforms into a solid, rubbery substance. Second, you incorporate a finely divided inorganic filler along with 12 percent zinc hydroxide by weight. Finally, you knead this mixture until it reaches a specific consistency that is both putty-like and elastic, allowing it to bounce like a ball or stretch like taffy.
The gap
What does this patent NOT cover?
- Does not cover the use of non-silicone base polymers for creating elastic putty.
- Does not cover processes that exclude the specific addition of zinc hydroxide as a hardening or stabilizing agent.
- Does not cover liquid silicone compositions that have not been processed into a solid, elastic state via boron heating.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
The innovation lies in using zinc hydroxide as a specific additive to stabilize the silicone-boron matrix, preventing the material from becoming too sticky or losing its shape over time.
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
Silly Putty
Bouncing putty toys
Early silicone-based industrial sealants
Why it matters
The bigger picture
This patent captures the early development of silicone-based elastomers, which became the foundation for materials like Silly Putty. It represents a significant moment in polymer science where chemists learned to manipulate silicone chains to create materials with strange, non-Newtonian physical properties.
Filed
December 23, 1944
Granted
February 13, 1951
Market context
Who's building on this
Companies in this space
General Electric was the primary pioneer in this space, and their early work on silicones paved the way for modern companies like Dow and Wacker Chemie. Today, these companies continue to refine silicone polymers for everything from medical devices to aerospace gaskets.
Market impact
This patent helped establish the commercial viability of silicone polymers beyond simple lubricants. It triggered interest in creating 'bouncing putty' as a consumer noveltynoveltyThe requirement that an invention be different from anything publicly known before its priority date.Read more → and demonstrated the versatility of silicone chemistry for industrial applications requiring unique elastic properties.
Claim 1 — Plain English
What this patent covers
The patent describes a three-step chemical process to create a unique elastic material. First, you heat liquid dimethylsiloxane with a boron-based catalyst, such as boric acid or borax, until it transforms into a solid, rubbery substance. Second, you incorporate a finely divided inorganic filler along with 12 percent zinc hydroxide by weight. Finally, you knead this mixture until it reaches a specific consistency that is both putty-like and elastic, allowing it to bounce like a ball or stretch like taffy.
The clever bit
The innovation lies in using zinc hydroxide as a specific additive to stabilize the silicone-boron matrix, preventing the material from becoming too sticky or losing its shape over time.
What it does not cover
- Does not cover the use of non-silicone base polymers for creating elastic putty.
- Does not cover processes that exclude the specific addition of zinc hydroxide as a hardening or stabilizing agent.
- Does not cover liquid silicone compositions that have not been processed into a solid, elastic state via boron heating.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
This patent is in the public domain
See the Freedom to Build guide — what is free to use, what is not, and how to cite this patent.
PatentBrief Score
Impact Score
Moderate
Citation count
38/40
Highly cited
Claim breadth
1/20
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
20/20
Major company or institution
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
$52K – $166K
Midpoint $104K · 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.
Patent Claims
1 independent claim · 0 dependent
Claims are the legal boundaries of the patent. An independent claim stands alone. A dependent claim adds limitations to its parent, narrowing — but not broadening — the scope.
The original legal language
Original claims
2 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Wright, J. G. E. (1951). How to Make Silly Putty Using Silicone and Zinc (U.S. Patent No. 2,541,851). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/2541851/silly-putty-bouncing-silicone
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 to Make Silly Putty Using Silicone and Zinc cover?
A 1944 chemical process for turning liquid silicone oil into a bouncy, stretchable, putty-like material by adding boron compounds and zinc hydroxide.
Who owns patent US 2541851?
General Electric Co owns this patent, granted in 1951.
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 2541851 cited by?
This patent has been cited by 80 later patents that build on its ideas.
What problem does this patent solve?
This patent captures the early development of silicone-based elastomers, which became the foundation for materials like Silly Putty. It represents a significant moment in polymer science where chemists learned to manipulate silicone chains to create materials with strange, non-Newtonian physical properties.
What does this patent NOT cover?
Does not cover the use of non-silicone base polymers for creating elastic putty.
Same assignee
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