Watch your pH
When cooking acidic sauces, stews and the like, it helps to know the general pH level (i.e. acidity) of your ingredients. Canned tomatoes—a common ingredient for many sauces‚ have a pH of around 4, which is less acidic than wine (3 to 4), vinegar (2.5), and citrus juice (around 2). The takeaway? It’s safe to cook tomato- and wine-based sauces in cast iron, but you should save the vinegary pan sauces for stainless-steel pans—or dilute the vinegar (or citrus) with water or stock.
