Why Does Morton Salt Use the Slogan When It Rains it Pours?

Morton Salt Company has been using the slogan when it rains it pours, together with the familiar Morton Salt Girl carrying her umbrella, since 1911. I’ve always found this a curious choice since the idiom alludes to trouble which comes in multiples.

Morton, however, was referring to its salt ability to pour even when it rains. This logo was based on what the company called a new “packaging innovation” which allowed its salt to do something we take for granted today: Pour out of the container, reliably.

Before Morton’s innovation, during humid conditions salt would cake up in the container and form lumps. Of course, you’ve seen this happen in your salt shaker, which more easily allows the salt to absorb moisture. What Morton did has nothing to do with the package, though. They introduced what today is a typical added ingredient, a free-flowing or anti-caking ingredient. Anti-caking ingredients are very important additives in the food industry, and they do exactly what the name implies: Keep granulated or powdered products from caking or turning into a solid lump. ¹Karukstis, Kerry K., and Van Hecke Gerald R. Chemistry Connections: The Chemical Basis of Everyday Phenomena (Complementary Science Series). Academic Press, 2003

These are also added to powdered products like baking powder, powdered sugar, and products such as dry cake mixes. They are also used in places you would not expect, such as shredded cheese and instant soups. In addition to keeping mixes free-flowing in the package, they also serve as a manufacturing aid to help separate dry crystallized ingredients that would otherwise stick together. These additives are intermediate-stage additives. For example, while an anti-caking agent serves to keep a cake mix from lumping, the agent serves no purpose once the cake is actually baking. ²Aramouni, Fadi, and Kathryn Deschenes. Methods for Developing New Food Products: An Instructional Guide. DEStech Publications, 2015. ³ Emerton, Victoria, and Eugenia Choi. Essential Guide to Food Additives. Leatherhead Publishing, 2008.

Free-flowing agents do their job by absorbing a lot of moisture without actually dissolving. There is nothing very miraculous or mysterious at work here. If you’ve ever put rice in your salt shaker to keep the salt from clumping, you’ve used a free-flowing agent! Rice is able to absorb a lot of moisture, thus keeping it out of the salt.

The first anti-caking ingredient Morton Salt used was magnesium carbonate or MgCO₃. Today, however, they use calcium silicate (CaSiO₃). Calcium silicate can absorb a whole lot of liquid while still remaining a free-flowing powder. It can absorb, in fact, 1 to 2.5 times its own weight in liquid but when it comes to water, our chief concern, its absorption capacity is more like 600%. Yes, that’s right, it means this stuff can absorb 600 times its weight in water. ⁴Karukstis, Kerry K., and Van Hecke Gerald R. Chemistry Connections: The Chemical Basis of Everyday Phenomena (Complementary Science Series). Academic Press, 2003

All this means that it only takes a very small amount added to the salt to do the job. Morton adds less one one-half percent by weight of calcium silicate, ensuring that your salt keeps on pouring.

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