National Day

National Slime Day

Celebrated on 12/07/2026

Quick Fact

National Slime Day, celebrated on August 19th, originated from the 1976 invention of the iconic green slime by Mattel toy scientist David S. Wilson, who accidentally created it while trying to make a new type of putty. The holiday gained traction in the 2010s with the rise of DIY slime videos on YouTube, where #slime videos have accumulated over 50 billion views worldwide.

Origins and Establishment of National Slime Day

National Slime Day was first observed in 2017, created by the toy company Mattel to celebrate the 40th anniversary of its popular slime product. The date, August 19th, was chosen to commemorate the original patent filed by Mattel in 1976 for a "stretchy, gooey substance" that would become known as slime. The patent was filed by David S. Wilson, a chemist at Mattel, who had accidentally invented the substance while attempting to create a new type of putty. The initial product, marketed as "Slime," was a vibrant green, non-toxic goo that came in a small plastic trash can, becoming an instant sensation.

Evolution and Modern Commemoration

Over the decades, slime evolved from a simple toy into a global phenomenon, especially with the rise of social media. In the 2010s, DIY slime tutorials exploded on YouTube and Instagram, leading to a resurgence of interest. National Slime Day now features slime-making contests, online challenges, and special promotions from toy retailers. Schools and community centers often host slime science workshops, highlighting the chemistry behind the substance. The day has also become a platform for promoting STEM education, as slime-making demonstrates principles of polymers and non-Newtonian fluids.

Facts & General Observations

  • The most popular slime recipe on YouTube has over 100 million views, and the hashtag #slime has been used in more than 20 million Instagram posts.
  • Slime has become a multi-million dollar industry, with specialty slime shops selling custom scents, colors, and textures for up to $30 per container.
  • In 2019, the largest slime ball ever made weighed 1,200 pounds, created by a group of YouTubers in Los Angeles.

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