On May 8, 2021, Spencer Silver, co-inventor of 3M Post-it® Notes, died at the age of 80. The inventor’s death has made national news, and inevitably the event has prompted retelling of the Post-it story, i.e., isn’t it amazing what can grow out of an accidental discovery.

But there is more to Post-it Notes than meets the eye, as discussed in this article, along with lessons for business owners, managers, and counsel:

  • Who—like 3M—can benefit from a patent,
  • What they should patent,
  • Why they should apply for patent, and
  • When they should start the patent process.

(I call these considerations the 4 W’s of Patent.)

We’ll also consider the important role of trade secrets and the need to select, clear, and register a trademark in the nature of Post-it®.

Spence Silver invents—and 3M patents—a poor adhesive

Spencer Silver, or “Spence,” as he was known to his friends, must have been a great guy to know. Married to his wife from 1965 until the end of his long life, he held a Ph.D. in chemistry and no fewer than 37 patents.

It is commonly said—and it’s true—that in 1968 Spence invented a sorry excuse for an adhesive. That’s one of 3M’s main product lines, adhesives, but Spence’s shiny new microspheres didn’t stick very well at all! The new composition had all the earmarks of a failure. But 3M has never been a company to let a novel formulation go without a patent, thus, U.S. Patent 3,691,140 was issued to Spence and 3M in 1972, only 18 months after the filing of the patent application.


The patented “acrylate copolymer microspheres” invention of Spence and 3M was greeted by the world with a collective yawn.

But Spence didn’t give up. He presented in-house seminars for his fellow 3M scientists, extolling the virtues of his “solution waiting for a problem to solve.” See 3M press release of May 12, 2021. In 3M’s culture of innovation and intellectual property, such collaboration was encouraged.

bootlegging encouraged

One 3M inventor could pick up the trail where another left off, in what 3M has described as the “time honored practice” of “bootlegging.” Century of Innovation: The 3M Story at p. 19 (3M, 2002). “The leaders of 3M understood that no one should stand in the way of a creative person with passion because that person might invent the next product or manufacturing breakthrough.” Id.

Art Fry invents—and 3M patents—sticky notes

The adhesive story gained a pick-me-up, or should we say a lesson in stick-to-it-iveness, in 1974, when Spence’s colleague Art Fry, a chemical engineer, came up with the idea of using Silver’s invention to prevent paper bookmarks from falling out of his hymnal when he sang in church.

bored by sermon or inspired to invent?

It wasn’t easy to apply a poor adhesive to a strip, to make the strip fasten “just so” to the hymnal, and then upon removal of the strip for the adhesive to stay on the strip instead of transferring to the hymnal. It took years of work to figure out how to make the removable sticky notes and to see how they would fare in the marketplace.

3M test-marketed the product as the “Press ‘n Peel” bookmark in stores in four cities in 1977, but results were disappointing.

if at first you don’t succeed

A year later, 3M tried again, giving away thousands of free samples to consumers in Boise, Idaho. This time more than 90% of the consumers said they would buy the product. In late 1979, 3M introduced Post-it Notes in a limited release, which they followed in 1980 with a national rollout, and which they expanded the next year to include Canada and Europe.

In the mid to late 1970s and the first three years of the 1980s, 3M continued to file patent applications claiming sticky microsphere inventions. None of the resulting patents, however, seem to have been credited in connection with the early success of Post-it Notes.

wake up and file for another patent

Somewhat surprisingly, insofar as can be determined from public records, it wasn’t until 1984 that 3M pursued a patent on Fry’s improved version of “repositionable” sticky notes.

The question of patent law raised by 3M’s apparent delay of four years after the national rollout is called the “statutory bar,” which precludes an inventor and his company from validly patenting a product that has been in public use or on sale for more than one year. Perhaps the claimed technology was improved shortly before the 1984 filing. Or perhaps the method claims ultimately allowed were considered novel because nobody knew exactly how the sticky notes were made.

Fry’s method claims also are unusual in that they define the method partly based on the result of obtaining sticky notes that will stay adhered to newsprint for two weeks. It seems odd that patentability of Post-it Notes should depend on whether you can mark the crossword puzzle until you get around to it.

Perhaps 3M was caught by surprise when Post-it Notes succeeded beyond the company’s wildest expectations, and they had to do some scrambling to try to extend the exclusivity provided by Spence’s ‘140 patent, which had already run several years of its 17 year term.

out of the Fry pan and stuck in the Patent Office

In any event, Fry’s first patent application, filed by 3M in 1984, was abandoned. His second application also was abandoned.

The third time was the charm for Fry, i.e., the third application in Fry’s chain, filed in 1986, resulted in issuance of U.S. Patent 5,194,299 in 1993—some 25 years after Spence’s invention was completed, almost 20 years after Fry’s first efforts were made, and nearly 10 years after Fry’s first patent application was filed.

At long last, the 1993 issuance of U.S. Patent 5,194,299 was extended to Art Fry in his own right—though assigned to his employer 3M—and it was limited to the “method of making” the sticky notes.

Thus, ironically, Fry’s method of making successful sticky notes ran into a lot more resistance from the Patent Office than Spence’s initial failure of a microsphere composition.

Many sources assume that “the patent” covering 3M Post-it Notes expired in 1997. This is curious, because the old patent term was 17 years from the issue date and the new patent term is 20 years from the earliest effective filing date, and under either scheme, neither the Spence ‘140 patent nor the Fry ‘299 patent seem to match up with expiration in 1997, at least not in the ordinary course of the lives of patents. These are the kinds of timing and strategy issues that are probed when patents are tested in court—challenges that are unlikely to occur now, so many years after the patents have expired.

The happy careers of Spencer Silver and Art Fry

You might wonder whatever happened to Spence Silver and Art Fry. The answer is that they both had long, successful careers with 3M. They were recognized and well paid for their work, though the lion’s share of the profits—indeed all of the profits—from Post-it Notes went to their employer.

Art Fry, born in 1931, was admitted into 3M’s Carlton Society in 1983, the highest honor given to a 3M scientist. He retired in 1992.

with a new heart, Spence felt too good to work

Spence Silver, born in 1941, also was a member of the Carlton Society. He had a heart transplant in 1994, and he retired two years later, saying he “felt too good to work every day.” He went on to enjoy another 25 years of painting, cooking, gardening, and traveling.

National recognition for 3M, Spence, and Fry

Sometime around 1995, the aura of Post-it Notes transcended the prominence of the Fortune 500 company and the world of office products; in that year, 3M was awarded the National Medal of Technology based in part on the success of Post-it Notes.

Similarly, in 2010, Spencer Silver and Art Fry were inducted into the National Inventors Hall of Fame based on the ‘140 and ‘299 patents, respectively.

$2 billion a year from sticky notes

According to figures from MarketWatch, sales of Post-it Notes and generic sticky notes now add up to $2 billion per year, and sales continue to grow year after year. Despite the expiration of 3M’s basic patents, the Post-it brand enjoys over 75% market share. That amounts to $1.5 billion per year in present gross revenue for 3M.

When Post-it Notes were rolled out on a national scale in 1980, they probably hit $250 million in annual sales pretty quickly, and the sales probably grew rapidly to $1.5 billion per year before “the patent” expired around the year 2000. During that period of exclusivity, 3M was able to command a fair price and healthy margins. Let’s say that sales averaged about $900 million per year for those first 20 years, for a subtotal of $18 billion in revenue for that period.

When competitors entered the market, 3M probably had to lower its price, and by definition its market share dropped. A quick spot check of the market indicates that generic sticky notes currently sell for about a 15% discount from the brand price.

Let’s say that 3M averaged $1.3 billion in annual revenues for the last 20 years, for a subtotal of $26 billion. That’s $44 billion in total gross revenue for 3M so far from branded sticky notes.

a cool $50 billion from Post-its

Allowing a few billion for sales in the near future, 3M soon will hit $50 billion in total gross revenues from Post-it Notes, even in the unlikely event that sales fall off a cliff in three or four years.

The 3M Post-it story is somewhat like that of Lego, in that both product lines are dominated by single companies, single brands, with large market shares and profitable sales that outlived the original patent rights. See my article titled Billion Dollar Lego Patent.

Lessons from 3M and Post-it Notes

Having examined the Post-it story in some depth, what can business owners, managers, and counsel learn from 3M and Post-it Notes? In the following discussion, let’s consider the “4 W’s of Patent,” and then let’s address the role of trade secrets and trademarks.

Who should apply for patent?

When people think of an inventor, they might picture a tinkerer working in his or her garage, basement, or kitchen. Indeed, many independent inventors manage to beat the odds and to succeed in inventing, patenting, and selling their new, improved products. That’s the right order: First invent, then file for patent, and then go out and sell the product.

More typically, however, the greatest successes are accomplished by skilled inventors who know the industry and have the technical “toolkits” needed to solve customers’ problems and fill market needs—and even in rare cases (such as Post-it Notes and iPhones) to create a market where there was none.

Spencer Silver had a Ph.D. in organic chemistry. Art Fry had a degree in chemical engineering. Both were employed by 3M and given all the resources they needed to invent new adhesive products.

In other words, the entity most likely to succeed in inventing, patenting, making, and selling a new improved product is the company that is in the business. That company—often a specialty company like 3M—typically employs skilled people—perhaps including scientists and engineers—who develop new and improved products.

3M started small. They were in business for many years before they developed their most famous product, namely, Scotch Tape. To this day, they are best known for adhesives and abrasives, expanding naturally into such lines as reflective materials, worker safety, and medical products. They have laid down thousands of patents to protect the exclusivity of their inventions.

For more on this subject, see my article titled Who Should Apply for Patent.

What should you patent?

It might seem self-evident that a company should focus its IP budget on its core product lines. But there is a great temptation, instead, to throw money at the “new, new thing.” I believe that this is partly because inventors and their companies tend to get bored by their own success. They tend to overlook the patentability and the value of minor improvements to their core products. But that’s the field in which there is the greatest likelihood of success: It’s the product that is in your wheelhouse. The author Russell Conwell explored this familiar yet surprising truth in the classic Acres of Diamonds (1890).

Most of 3M’s patents, both currently and historically, are directed to adhesives, abrasives, and similar products. You won’t see them patenting or selling lawn mowers, though you might see 3M earplugs for hearing protection.

Here’s another lesson from 3M: Aim for a thicket of patents around your core product lines. Taking Post-it Notes as an example, 3M has been granted well over 200 U.S. patents that cite Spence’s landmark ‘140 patent. Most of them, not surprisingly, are directed to sticky substances used to attach one item to another. There’s no end to what can be created in the way of adhesives—no end to new products that make use of such technologies.

Indeed, 3M has been granted more than 100,000 patents worldwide. In 2020, the company was issued 668 U.S. patents, ranking among 100 top organizations worldwide for grant of U.S. patents. See my article titled What Should You Patent.

A good place to start your inventive activity is with products that you actually intend to make and sell. This was one of the secrets of Thomas Edison’s success. He never bothered to invent anything unless he intended to start a business to make and sell the patented product. If you’re already in the business, it’s an even easier decision to develop and patent new technologies that fit into an existing product line or a natural extension of that line.

For more on the importance of focusing your inventive efforts and your patents on those that you intend to commercialize, see my article titled Science vs. Technology: Volta vs. Watt and Edison.

When you set out to build a patent portfolio, as in every worthwhile endeavor, you should be prepared to proceed even in the face of rejection and opposition. As discussed above, 3M did not stop with one patent on microspheres and Post-it Notes. Bear in mind, too, that it took almost 10 years after 3M’s filing of Art Fry’s “repositionable” sticky notes patent application for the ‘299 patent to issue. It takes skill and persistence to obtain the issuance of a patent even for a landmark invention.

For more on the subject of building an IP portfolio and dealing with the Patent Office, see my article titled Build Your Patent Portfolio: Preparation, Prosecution, Appeals.

Why apply for a patent?

A patent, in essence, is the legal right to exclude others from making, selling, using, or importing the patented invention. The term is 20 years from the earliest effective filing date.

What’s in it for the company? The answer is that the exclusivity provided by a patent gives the innovator the chance to attain and maintain market leadership and to generate revenues, i.e., sales. A patent can give its owner the opportunity to set a fair price, without undue fear of being undercut by copyists, and to enjoy healthy margins, i.e., profits.

Last but not least, in helping to generate revenues and margins, a patent on a commercially successful invention adds to the capital valuation of the company.

In the case of 3M, the company’s market capitalization hit $100 billion in 2013, and it doubled from that figure by 2017. This occurred even long after the Post-it Notes patents had expired.

Perhaps 3M and Post-it Notes are an extreme case. They’re in the stratosphere, one might say.

Coming back to Earth, a start-up company can create its own niche and patent portfolio, generate sales and profits, and attract capital investment based on that performance.

For more on this subject, see my article titled Why Apply for Patent.

When to apply for patent?

As stated above, the right order is first invent, then file for patent, and last but not least, get out and sell the patented product. The U.S. Supreme Court has held that an application, if a patent is desired, should be filed as soon as the invention is “ready for patent,” which in the case of 3M, was both before and after Post-it Notes began to hit their stride.

I like to think of a patent application as a set of iPhone pics, description, and claims directed to an inventive product that has been developed preferably to the prototype stage. The new technology doesn’t have to be perfect. It might not yet even have a well-defined market.

Again, taking Post-it Notes as an example, Spencer Silver and 3M prepared and filed the microsphere patent application as soon as the technology was developed and tested in the secrecy of the laboratory.

When Art Fry picked up the trail and created repositionable notes, 3M filed another patent application. (In hindsight, they might have benefited from even more patent filings directed to Art Fry’s work: File early and file often.)

The point is to prepare and file a patent application as soon as it becomes apparent that an invention might have commercial applicability. Repeat. Soon you’ll have a portfolio of patents. Wait too long and you might miss a window of opportunity and the right to a patent.

For more on timing, see my article, When to Apply for Patent.

Trade secrets

An insight can be gained from an April 4, 2013, CNN article, in which Art Fry pointed out that trade secrets played (and presumably continue to play) an important role in 3M’s success with Post-it Notes. The equipment required to make Post-it Notes is expensive and complicated.

While the 3M patents arguably disclose sufficient details for “one of ordinary skill in the art” to practice the claimed inventions, that doesn’t mean that any Tom, Dick, or Mary could set up shop in their garage to make sticky notes. The machinery is too expensive and too complicated; there are significant barriers to entry, and once 3M gained a big head start, with years of exclusivity provided by patents, trade secrets, and trademarks, it became difficult for any competitor to obtain a toehold in the market.

Register that trademark

I’ve seen worse choices for a trademark than 3M’s original selection of “Press ‘n Peel” as a brand for its sticky notes. Simple as it is, though, it’s still too complicated. That early mark had three syllables (all or parts of three words) and it included an apostrophe. That made it hard to spell and hard to remember, which was problematic in the late 1970s (and which would be even more troubling in the era of the internet and Google searches),

Post-it® is an extremely valuable trademark, an exclusive brand that can last forever, i.e., for at least as long as the product is sold, which already is longer than the 20 year term (from date of first filing) of any recent patent.

By the way, initials or acronyms like 3M (for Minnesota Mining and Manufacturing) and IBM (for International Business Machines) generally are not strong brands, unless perhaps you have a few million dollars to spend on advertising and promotion over a period of decades. See A. Ries and J. Trout, Positioning: The Battle for Your Mind (1980).

One IP investment that is most likely to pay dividends is the registration of the company’s most important trademarks. See One IP Asset You Must Protect. The Post-it mark rises to that level of importance and value. (Can you think of another brand of sticky notes?)

Here, the registered trademark is helping to preserve 75% market share for 3M even long after the expiration of the patents. In fact, 3M owns several registrations for Post-it marks, with and without designs, as applied to various goods, dating all the way back to the mid-1970s. They even registered canary yellow as distinctive of their sticky notes.


Be like 3M, Spencer Silver, and Art Fry. They invented, patented, and sold Post-it Notes. They protected their trade secrets and trademarks. As a result, 3M Post-it Notes continue to bring in billions of dollars every year.

Here’s what you and your company can do: Invent new, improved products, especially those that are in your wheelhouse. Have patent applications prepared and filed to protect your inventions. Last but not least, make and sell the patented products for market leadership, revenues, margins, and capital valuation.