Locate nearby businesses that sell cast iron cookware. You can find cast iron pans at nearly any store that sells kitchen supplies, and you may also find them at hardware stores. Call the stores ahead of time to make sure they have cast iron cookware.
Read the label on the cast iron pan. In his book "How to Cook Everything Vegetarian," food journalist and author Mark Bittman points out that cast iron cookware should always be pure cast iron and not an alloy. The product label should clearly say if it's pure iron.
Pick up the pan. Frying pans made of cast iron should feel much heavier than those constructed of other materials, such as aluminum or steel. A sturdy frying pan should also be 1/8 inch thick at a minimum.
Look for a deep pan with straight sides. According to "Food & Wine," straight sides hold the oil better than do the curved sides some pans have. Straight sides may also help maintain a more even temperature throughout the oil.
Look for a pan with a helper handle. A helper handle is generally U-shaped and located on the opposite side of the main handle, which allows you to use both hands when you handle the pan. A cast iron frying pan may weigh up to 10 pounds, so a helper handle can make it easier to use.
Examine the entire frying pan to ensure it's one whole piece. A quality cast iron frying pan should never have bolted-on handles.