That brown stuff coming off your cast iron is usually flaking, carbonized oil (seasoning) or, if it's flaky and rough, rust, both signs that your pan needs a good clean and reseasoning; you can scrub it off with steel wool or a salt paste, then wash, dry thoroughly, and apply a new, thin layer of oil before heating in the oven.
Heat up the pan on medium, give it time to get hot, then pour 1⁄4 cup of white vinegar into it and scrape the surface with a flat ended spatula. Pour out the excess vinegar and wipe dry with a paper towel while the pan is still warm. This should leave with a squeaky clean, under-seasoned pan.
Is it normal for my cast iron to have black residue after cooking? Yes, it's normal because black residue is a byproduct of cooking. But excessive residue could mean you're using too much heat or the wrong oil.
Rust might be the greatest fear of anyone who owns cast iron, but luckily it's almost certainly not the end of your skillet. Cast iron can be pretty resilient, and even very rusty, damaged pans can be rehabilitated—and in most cases, the rust they're facing is pretty minor.
Brown spots on cast iron pans can be a sign of seasoning buildup or food residue. They appear when oil or food isn't evenly distributed. Over time, these spots darken, resembling rust. If the spots are flaky and feel rough, it's likely rust.
Here are a few signs it's time to replace your cast iron cookware.
There's nothing poisonous about rust. You can scrub the pans with steel wool to clean them. If it's flaky black nonstick , throw the pans away.
Cast iron rusts when exposed to moisture for long periods. A water soak can undo months of seasoning and require a full restoration. Wash quickly with warm water and a soft brush while the pan is still warm. Dry it immediately on low heat until all moisture evaporates.
Carbon Deposits
First, the black specks you see coming off into your food are not harmful. They are most likely carbon deposits. This happens due to overheating of fats and oils.
Is this OK? This dark residue that might come off the surface of your pan is burnt (aka carbonized) oil or fat; it's common to all cast iron skillets, and is not harmful to you.
This black residue from your cast-iron pan doesn't look great, but it's just seasoning and it's not harmful. Keep cooking in that pan, washing and drying and oiling it meticulously, and you'll see the issue clear up quickly.
White vinegar.
Gently heat a cup of white vinegar and apply it to the soleplate with a non-abrasive sponge to dissolve mineral deposits and limescale. Then, clean the vinegar off the plate with a damp cloth. To clean clogged nozzles, you can use a cotton bud dipped in white vinegar.
The only truly "bad" cast iron pans are the ones that are warped or cracked. Even then, depending on the circumstances you can sometimes still cook quite well with those. Good and bad cast iron are very subjective terms that can mean completely different things from one person to another.
So, is rust on cast iron dangerous? The short answer is no. According to Lodge Cast Iron, a company that manufactures cast-iron cookware and accessories in Tennessee, rust appears on cast iron when the pan or utensil has been exposed to moisture for prolonged periods of time and "is not harmful in any way."
Is Cast Iron Cookware Safe? It can be dangerous for individuals who already have high iron levels genetically like post-menopausal women. If they cook with cast iron, the extra iron may raise their iron level too high, causing iron toxicity.
There's no need to throw away a cast iron skillet that's a little (or a lot) rusty. In fact, the next time you stumble upon some rusty pots and pans at an antique store or flea market, imagine the potential! Follow these five easy steps to restore cast iron cookware to its former glory.
You shouldn't cook eggs in a cast iron skillet because they tend to stick, especially in new or poorly seasoned pans, leading to frustrating messes and potential damage to the pan's seasoning, though proper preheating, fat, and low-heat techniques can make it possible. The porous surface of cast iron, especially newer ones, grabs eggs, and its excellent heat retention can easily brown or overcook them, making delicate foods like eggs challenging compared to Teflon or stainless steel.
There aren't tons of ingredients that you need to avoid using in cast-iron cookware, but high-acid and vinegar-based foods and sauces can cause significant problems with the surface layer, particularly if you've spent time building up the slickness and seasoning.
Health concerns related to rust
Unless it's been left outside, it's unlikely your rusty cookware will have the bacteria that causes tetanus.
Your cast-iron skillet can last forever if you care for it properly—and use it frequently. Do so, and you'll have a pan you can cook with for decades. Learn basic cast iron care, also how to get a vintage cast-iron skillet into working shape for cooking at the link below.
Cast Iron Discoloration
Each time you cook in your skillet, it will gain and lose seasoning in different spots, which can cause some discoloration in the beginning. But as you develop more and more seasoning across the surface of the pan, you'll see its color even out and darken overall.