Known as Conversation Hearts, these little, heart-shaped candies inscribed with romantic messages have been a staple of Valentine’s Day wooing for decades. For those who are curious how this classic seasonal product is manufactured, Martha Steward takes viewers inside the Necco candy plant in Cambridge, MA to show the Conversation Hearts production process in this 2014 segment.

The process starts with pulverized sugar entering a large mixer from a hopper, where it is combined with corn syrup, gelatin, and dextrose. Workers then add flavors and colors are added to the mixture.

After that, 500 lb batches of the chunky material are pressed into shapes, and one of more than 500 “sayings” is etched into each individual candy piece. Next, the products are put into a dryer. The final step involves mixing the six different colors of hearts before they are packaged.

Stewart said the Necco facility in Cambridge produces more than 100,000 lb/day of Conversation Hearts in advance of each Valentine’s Day.