An eraser on a pencil: handy, but is it really an invention?
In a series of blog posts, Marco Coolen offers a glimpse into his work as a Dutch and European patent attorney at AOMB.
Published on November 1, 2026
Marco, a patent attorney at AOMB since 2013, shares his expertise on IO+ about patents—how they work, why they matter, and when they lose their value.
An eraser on the back of a pencil sounds like a brilliant idea. And to be honest: it really is.
Anyone who’s ever written something down incorrectly understands right away why. You make a mistake, flip the pencil over, and erase the problem. No searching for a separate eraser, no interruption, no hassle. It’s a solution that feels so logical that you can hardly imagine anyone ever having to think about it separately.
Marco Coolen, photo © Bart van Overbeeke
But that’s exactly where it gets interesting. Because simple, convenient, and commercially savvy doesn’t necessarily mean patentable. In the mid-nineteenth century, Hymen Lipman combined two familiar products: a pencil and an eraser. He initially obtained a patent for it. From a user’s perspective, that was perfectly understandable. The combination made the product more practical, more efficient, and more appealing to users.
Yet the patent was later declared invalid because the pencil still did what a pencil had always done. And the eraser did what an eraser had always done. They were simply placed closer together. Together, they were more convenient. But technically, there was too little that was new.
That’s what makes this example so valuable for entrepreneurs. Many commercial innovations arise precisely at this intersection. You combine existing components in a clever way, simplify usage, and create something whose value customers immediately recognize. That can result in a great product. But a patent requires more than that.
A patent doesn’t just ask whether something is convenient. It asks whether there is a technical contribution. Is there something new happening in how it works? Does it create an effect that goes beyond simply putting known components together? Do those components work together in a new way?
In the case of the pencil with an eraser, the answer was ultimately: no. The combination was practical, but not technically inventive enough. That doesn’t mean such ideas are worthless. On the contrary. Sometimes the commercial value lies precisely in simplicity, timing, and ease of use. The customer doesn’t need to know whether something is patentable. They just want the problem to go away. And the pencil with an eraser did that exceptionally well.
So the lesson isn’t that simple combinations never deserve protection. The lesson is that you have to look closely at where the innovation lies. Sometimes it’s in the combination itself. Sometimes in the way components work together. Sometimes in a production process or fastening method that makes the whole thing possible.
But sometimes it’s primarily a good product idea. And in that case, a different form of protection may be more appropriate. Think of a trademark, design, distribution advantage, or simply quickly capturing the market.
Lipman’s story clearly illustrates that innovation and patentability are not the same thing. An idea can be brilliant without resulting in a strong patent. And a patent always requires that one extra question. Not just: Does this work well? But above all: Is something technically new happening here?
The World of Patents
With the help of Dutch and European patent attorney Marco Coolen (AOMB), we can better understand the world of patents. How do they work, why are they important, and when do they lose their usefulness?