You’ve probably come across at least one video showing what happens when people microwave ivory soap, but have you ever wondered why it reacts that way? According to Steve Spangler, Proctor & Gamble whip lots of air into their ivory soap mixture before solidifying it to form bars. The air, along with moisture, gets trapped inside tiny bubbles throughout the bar. So when those bubbles are exposed to intense heat, they boil and expand causing it to foam up. Continue reading for more.

5. Flower

The name “Ivory” refers to a series of products created by the Procter & Gamble Company (P&G), including varieties of a white and mildly fragranced bar soap, that became famous for its pure content and for floating in water.

4. Is it a Good Idea?

Over the years, the bar soap has been altered into other varieties. P&G research revealed in 1992 indicated work in progress to create other varieties that do not float as the original and would sink due to the altered ingredients but avoid dissolving too fast.

3. Wrapped

New varieties of Ivory soap contain glycerin, do not dry the skin as quickly, and do not float, either. In October 2001, P&G tested the sinking bar soap as part of an advertising campaign to see if people would notice the sinking bars, even if given a cash reward.

2. Two Bars

Because Ivory is one of P&G’s oldest products (first sold in 1879), P&G is sometimes called “Ivory Towers” and its factory and research center in St. Bernard, Ohio is called “Ivorydale”.

1. Exploding

According to an apocryphal urban legend, later discounted by the company, a worker accidentally left the mixing machine on too long and the company chose to sell the “ruined” batch because mixing air longer did not change the basic ingredients of the soap. When appreciative letters about the new, floating soap inundated the company, P&G ordered the extended mix time as a standard setting. However, company records indicate that the design of Ivory was not the result of accident.