The most important thing to know about mercaptan is that it stinks. It doesn't smell slightly. It stinks. In a concentrated form, its smell is almost unbearable. And it takes only a few parts per million of mercaptan for the average person to wrinkle a nose and say, "what is that smell?" That is precisely why it is added to natural gas. You see, natural gas is both odorless and colorless. If mercaptans were not added, it would be hard for you to know that unlit natural gas was coming from your oven if you had a malfunction or leak. And leaks from ovens, furnaces, and water heaters would be nearly impossible to detect without expensive equipment. So mercaptan's smell is a very valuable safety feature. Mercaptans contain sulfur. That's what makes them smell. There are other uses for mercaptans in industry, including pharmaceuticals, jet fuel and livestock feed additives. They are used in many chemical plants. Mercaptans are similar to corrosive and toxic sulfur compounds found naturally in rotten eggs, onions, garlic, skunks, and, of course, bad breath. You know, things that stink. While there are many good places to use mercaptans, having them in contact with our beloved barbecue is not one of them- so in order to spare you their bitter flavor, we keep them OUT of our pits.