Cleaning crusty build-up on old cast iron cookware can be done using the following steps:
Scrub with a stiff brush: Start by scrubbing the cast iron cookware with a stiff brush or scrubbing pad to remove any loose particles or debris. Use hot water and avoid using soap at this stage, as it can strip away the seasoning.
Create a vinegar solution: If there are stubborn, crusty areas, you can create a solution of equal parts water and white vinegar. Pour the solution into the cast iron pan, ensuring it covers the affected areas.
Boil the vinegar solution: Place the cast iron cookware on the stove and bring the vinegar solution to a boil. Allow it to boil for a few minutes, ensuring the solution reaches the crusty areas.
Scrub again: After boiling, carefully remove the cast iron cookware from the heat and scrub the crusty areas once more with a stiff brush or scrubbing pad. This should help to loosen the build-up.
Rinse and dry: Thoroughly rinse the cast iron cookware with hot water to remove any remaining vinegar solution or debris. Use a paper towel or cloth to dry it completely.
Re-season: Once the cookware is clean and dry, it's essential to re-season it to maintain its non-stick properties and prevent rust. Apply a thin layer of cooking oil or solid shortening to the entire surface, including the handles. Wipe away any excess oil with a paper towel.
Bake for seasoning: Preheat your oven to a high temperature, such as 375°F (190°C) or 400°F (200°C). Place the cast iron cookware upside down on the oven rack or a baking sheet lined with foil to catch any drips. Bake for about an hour, then turn off the oven and allow the cookware to cool completely in the oven.
Regular maintenance and seasoning after each use will help prevent excessive build-up on your cast iron cookware. Avoid using harsh detergents or soaking the cookware for long periods, as these can damage the seasoning. Instead, clean it promptly after use using a brush or scrubber and hot water, and dry it thoroughly.