Have you ever looked at the bottom of an old LEGO brick and spotted the mysterious letters "Pat Pend"? Then you're holding a special piece of LEGO history in your hands! In this blog post, you'll discover exactly what Pat Pend means and why these bricks are so highly valued by collectors.
Pat Pend: An Old Secret Revealed
Pat Pend is simply short for "Patent Pending" - meaning LEGO had invented something revolutionary and applied for patent protection, but was still waiting for official approval.
LEGO printed these letters on their bricks between 1958 and approximately 1974 - a 16-year period while waiting for their patent to be finalized.
Why Was This Patent So Important?
In January 1958, LEGO faced a critical problem: their bricks fell apart too easily, and customers weren't satisfied. German retailers especially complained about how unstable the constructions were.
Godtfred Kirk Christiansen (son of LEGO's founder) then developed a brilliant solution: adding small tubes to the underside of each brick. This innovation made the studs of one brick fit perfectly between the tubes of another, creating the famous "clutch power" we know today - strong enough to hold, but easy enough to separate.
LEGO filed the patent on January 28, 1958, though it wasn't officially approved until 1962. However, LEGO continued printing "Pat Pend" on bricks until all old molds were exhausted around 1974.
How to Recognize Pat Pend LEGO
The beauty of vintage LEGO is you can easily identify which era a brick comes from. Pat Pend bricks have several distinctive features:
- The Text Itself
The most obvious identifier is the "Pat Pend" or full "Patent Pending" text printed on the bottom or inside of the brick. - The Small Sprue Mark
All Pat Pend bricks feature a small protrusion on one side - a tiny bump where the brick was attached to the mold during manufacturing. Later production methods eliminated this mark. - The Logo
The earliest Pat Pend bricks (until approximately 1963) display the original LEGO logo, which later evolved into the modern design we recognize today. - The Plastic
The very first Pat Pend bricks were manufactured from Cellulose Acetate, a plastic that warps over time. From 1963 onwards, LEGO switched to ABS plastic, which remains the standard today.
Pat Pend Obscured: A Rare Phenomenon
There's also "Pat Pend Obscured" - bricks where the text was removed from the mold, leaving only a faint mark or bumpy area. This occurred during the transition period after patent approval, when LEGO still utilized existing molds.
Why Are Pat Pend Bricks Valuable?
For LEGO collectors, Pat Pend bricks are highly sought after, and for good reasons:
- They're Old and Rare
LEGO stopped producing Pat Pend bricks in 1974, meaning even the newest examples are now over 50 years old. Rarity drives collector interest and value. - They Tell LEGO's Story
These bricks document LEGO's evolution from a small toy company to the global brand it is today. They mark the pivotal moment when LEGO invented the iconic building system still used worldwide. - They Can Be Worth Serious Money
Vintage LEGO sets appreciate significantly in value over time. Unopened sets from 1987-2015 and sets containing Pat Pend bricks can be even more valuable due to their rarity.
The Timeline of LEGO Patent History
Here are the key milestones:
- 1949-1958: First plastic LEGO bricks, without the tube system
- 1958-1962: Pat Pend period begins - patent filed but awaiting approval
- 1962-1974: Patent officially granted, but "Pat Pend" marking continues
- 1974-1979: Transition years mixing old and new production
- 1980-present: Modern LEGO without Pat Pend markings
Tips for Authenticating Your Vintage LEGO
Wondering if you have Pat Pend bricks in your collection? Here's what to check:
- Turn the brick over and examine the underside for "Pat Pend" text.
- Look for the small sprue mark on the brick's side.
- Verify the logo style - old versus modern LEGO branding.
- Test the plastic - does it feel brittle or show warping? This indicates very early production.
- Inspect the tubes - early versions have different tube configurations.
Important note: Not every vintage brick displays "Pat Pend" - some parts were too small for the text. Absence of marking doesn't automatically indicate a newer brick.
More Than Just Letters
"Pat Pend" represents far more than two mysterious words on old bricks. These markings commemorate a revolutionary moment in toy history - the foundation for billions of creations built by children and adults worldwide.
Next time you encounter vintage LEGO, take a moment to examine the underside. You might just be holding a piece of history!
