Most of us have probably wondered how each M&M is so perfectly marked with that signature white m. The production of the candy that “melts in your mouth and not in your hand” includes many different steps.

First, the chocolate concoction is made and then poured into small round molds to form the cores of the M&Ms. These chocolatey centers are tumbled to create smooth circular surfaces, which will then be covered with a colorful liquid coating.

Once the exterior liquid has dried to form the hard shell, each candy piece ends up held in an indentation on a conveyor belt that whisks them away to be stamped with the signature m. The actual process for applying each m is similar to the offset printing process. So, what is offset printing?

Offset printing is widely used to produce high quality images on a variety of materials such as paper, canvas, or, in this case, candy. Essentially, this type of printing means that rather than having an image directly stamped onto a piece of material, the image is transferred, or offset, to an intermediate surface first.

The first step in offset printing includes inking an original image onto metal plates. The image from the plates is then transferred to a rubber cylinder, known as a blanket, which acts as an intermediary between the metal plates and the final printing surface. The final step includes offsetting the original image from the blanket to the desired printing surface.

This intermediary rubber blanket is particularly needed in the case of M&Ms which are relatively fragile and rounded. By careful design and calibration of the press, the rubber blanket only presses against the candy just enough to transfer the m without damaging the outer shell of the M&M.

This printing method also significantly reduces the wear on the master metal plates, so they last much longer. This is good considering on average around 2.5 million M&Ms are branded with an m each hour.

Of course, with this type of volume, it is nearly impossible to ensure each candy piece is shaped perfectly, particularly with peanut M&Ms which are not particularly uniform. As a result, despite careful calibration, some M&Ms do make it through the production process without an m. However, these are not considered rejects by any means. Rather than risk cracking the hard outer shell, the printing machine is designed to let overly misshaped M&Ms pass through without being stamped. In other words, the lack of an m on an M&M candy is totally intentional. Waste not want not and all that.

Incidentally, if you’ve ever wondered what the “Ms” stand for in the name “M&Ms,” wonder no more- In 1941, Forrest Mars Sr., of the Mars candy company, struck a deal with Bruce Murrie, son of famed Hershey president William Murrie, to develop a hard shelled candy with chocolate at the center.  Mars needed Hershey’s chocolate because he anticipated there would be a chocolate shortage in the pending war, which turned out to be correct.

The deal gave Murrie a 20% stake in the newly developed M&M; this stake was later bought out by Mars when chocolate rationing ended at the end of WWII.

The name, thus, stood for “Mars & Murrie,” the co-creators of the candy.

If you liked this article, you might also enjoy our new popular podcast, The BrainFood Show (iTunes, Spotify, Google Play Music, Feed), as well as:

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• Inventing Reese’s Peanut Butter Cups
• Why Sugar Doesn’t Spoil
• Why Pop Rocks Pop

Bonus Facts:

• The ink used on M&Ms is a type of vegetable dye.
• The “M&M” was modeled after a candy Forrest Mars, Sr. encountered while in Spain during the 1930s.  During the Spanish civil war, he observed soldiers eating chocolate pellets with a hard shell of tempered chocolate.  This prevented the candies from melting, which was essential when included in soldiers rations as they were. And, in fact, during WWII, M&M sales skyrocketed in popularity thanks to the fact that they were included as part of United States’ soldiers rations for the very reason soldiers in the Spanish civil war had an earlier version of them in their rations.
• The “M” printed on the M&Ms was originally printed black.  This was changed to white in 1954.
• William Murrie, father of Bruce Murrie, was originally hired by Milton Hershey in 1896 as a salesman.  In his first week on the job, he managed to over sell the plant’s production capacity.  This so impressed owner Milton Hershey that he tabbed Murrie to be the future President of Hershey; this later happened in 1908, a position he held until retiring in 1947.
• When William Murrie first took over running Hershey, the annual sales of the company was $600,000.  Upon his retirement in 1947, he had grown the company to gross annual sales of $120 million; so over the span of those 39 years, he increased the annual sales an average of around 15% per year.
• In the 1920s, Murrie tried to convince Hershey that they should produce a chocolate bar with peanuts.  Hershey didn’t like the idea, but let him go ahead as long as the bar wasn’t under the Hershey brand name.  And so, in 1925, the “Chocolate Sales Corporation,” a fictitious company Murrie came up with, debuted the “Mr. Goodbar,” which was wildly successful.
• For a fun experiment that demonstrates the rule “oil and water don’t mix” when M&Ms are place in water, the m will eventually peel away from the candy shell and float to the top.