Tim Chin is a professional cook and writer who has contributed to Serious Eats and America’s Test Kitchen. A graduate of The International Culinary Center, Tim has cooked at restaurants in New York and Boston, working at Rouge Tomate, Northern Spy, and BiSq.

Tim Chin

If cheese has a problem, it’s that it’s an unreliable melter.American cheese stays perfectly ooey-gooey in a <a href="https://www.chefsteps.com/recipes/how-to-make-the-ultimate-grilled-cheese-sandwich-at-home">grilled cheese</a>, and a box of Velveeta shells gets you a smooth, silky, and oh-so-creamy plate of mac. But give a couple chunks of your favorite aged Parm a blast of heat, and they’ll turn into an oily, greasy, hardened mess.Why do some cheeses melt while others turn into greasy blobs? And why do processed cheese products like Velveeta and American cheese melt even more readily than raclette?To answer these questions, you need a basic understanding of what cheese consists of, the differences between cheese varieties, and how additives called melting salts chemically alter cheeses to improve their ability to melt without turning into a mass of coagulated protein and leaking fat.

The Science of Melty Cheese