You can freely build on How to Make Silly Putty Using Silicone and Zinc
This patent expired in 1968. Every claim — 1 independent, 0 dependent — is now unenforceable. Anyone can use, reproduce, manufacture, sell, or offer for sale this technology without a license.
Original assignee
General Electric Co
Patent granted
1951
Expired
1968
Forward citations
80
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.
What is now free to use
All 1 claims of US 2541851 are in the public domain. Specifically:
Claim 1: THE PROCESS WHICH COMPRISES (1) HEATING A MIXTURE — 1 specific element
The 0 dependent claims add narrowing limitations and are also free.
What is NOT covered
Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.
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.
Who is building on this today
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.
Products built on expired version of this technology
Silly Putty
Bouncing putty toys
Early silicone-based industrial sealants
How to cite this patent in your documentation
General Electric Co. US Patent 2541851. Process for making puttylike elastic plastic, siloxane derivative composition containing zinc hydroxide. Granted 1951, expired 1968. Now in the public domain.
Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.
PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.