Reviving Cast Iron: Restore And Re-Season

Cast iron pans are a home chef's best friend. They are hard-wearing, versatile, and can be used anywhere from ovens to grills, and even on an open flame. Plus, unlike ceramic or coated cookware, cast iron pans only get better with age. However, they can become rusty and damaged and may need to be restored. This can be done by stripping off old seasoning, removing rust, and re-seasoning the pan.

Restoring an Old Cast Iron Pan

Removing rust with vinegar

To start, prepare a tub big enough to accommodate your skillet or clean and plug your sink. Fill your tub or sink with enough vinegar to completely submerge your skillet. It is important to dilute the vinegar with water, as undiluted vinegar can eat away at the iron under the rust. For a 50/50 mixture, measure out equal parts of water and white vinegar in a separate bucket, pan, washbowl, or sink.

After an hour, pull the pan out and scrub it with a non-abrasive sponge to coax away the rust. If the rust does not come off, let the pan soak for another 15 to 30 minutes, checking frequently, and then repeat the scrubbing process. Once the rust is removed, be sure to give the pan a thorough rinse to ensure all of the vinegar is washed off.

After rinsing, dry the pan thoroughly. Place it on the stovetop over low heat for a few minutes to ensure it is completely dry. Then, to prevent rusting, oil the pan immediately.

Using lye to remove old seasoning

Lye is a highly alkaline substance derived from wood ashes. It is often used in soapmaking, but it can also be used to remove old seasoning from cast iron pans. Here's a step-by-step guide on how to use lye to restore your old cast iron pan:

Step 1: Prepare the Lye Solution

Lye is a caustic substance, so it must be handled with caution. Always wear heavy-duty, long-cuffed chemical-resistant gloves, eye protection, and cover any exposed skin on your arms and legs. The lye product should be 100% sodium hydroxide crystals. Use one pound of lye crystals per five gallons of water. It's important to always add the lye to the water, never the reverse, to avoid a violent thermal reaction.

Step 2: Create a Lye Bath

Place your cast iron pan in a sturdy container made of UV-resistant plastic, such as a large plastic bucket or trash can with a secure lid. The container should be big enough to completely submerge the pan in the lye solution. If you're working with multiple pans, choose a container that can accommodate them all.

Step 3: Soak the Pan in the Lye Bath

Carefully place the cast iron pan in the lye bath and let it soak for at least 24 hours. The longer you soak the pan, the more effective it will be at removing the old seasoning. Lye won't harm the metal, so you can leave the pan in the solution indefinitely without worrying about damage.

Step 4: Remove the Pan from the Lye Bath

After the desired soaking time has passed, carefully remove the pan from the lye bath using tongs or thick gloves. Transfer the pan to a safe area where you can scrub and rinse it without risking skin irritation.

Step 5: Scrub and Rinse the Pan

Use a nylon scraper or brush to gently remove thick clumps of dissolved seasoning. Then, rinse the pan thoroughly with cold water while scrubbing it with steel wool and/or a handheld stainless steel brush. Avoid using brass brushes or power tools, as they can cause permanent damage to the cast iron. Repeat the scrubbing and rinsing process as needed until all the seasoning is removed.

Step 6: Neutralize and Rinse Again

To neutralize any leftover lye, scrub the pan with citric acid or lemon juice, and then rinse it with water again. Dry the pan thoroughly with a towel and heat it on a burner until it's completely dry.

Step 7: Re-season the Pan

Once your pan is clean and dry, you can re-season it by applying a thin layer of oil to all surfaces and placing it in an oven heated to 450–500 degrees F for about an hour. This process will give your cast iron pan a new, non-stick coating.

Electrolysis for simultaneous cleaning and rust removal

Electrolysis is a safe, cheap, and simple way to remove rust from cast iron without damaging the pan. It is a preferred method of cast iron restorers and collectors as it doesn't cause scarring or pitting on the pan.

How to Set Up Electrolysis for Cast Iron Restoration:

Firstly, gather your supplies:

• A non-conducting container, such as a large plastic bucket or a plastic barrel with the top cut out.
• Sacrificial anodes made of regular steel or carbon steel (not stainless steel). Sources include old rebar, plain steel sheeting, or cut-up coffee cans.
• Zip ties to mount the anodes to the tank.
• Wire to connect the anodes, rated for at least double the load of the charger.
• Washing soda (sodium carbonate) to create the electrolyte solution. Do not use baking soda.
• Bare steel wire, such as rebar tie wire, for hanging the pan inside the tank.
• A piece of lumber or rebar to hang the cast iron.
• Water to submerge the cast iron.
• A manual car battery charger, between 2 and 10 amps. An automatic charger won't work due to its safety features.
• Rubber gloves for protection.

Setting Up the Electrolysis Tank:

• Drill holes at the top of the container and use zip ties to mount the anodes.
• Attach the anodes together using wire.
• Add washing soda to the empty tank, then pour in water. Use 1/2 cup of washing soda for every 10 gallons of water.
• Wrap one end of the steel wire around the lumber/rebar and the other end around the handle of the cast iron.
• Rest the lumber/rebar across the top of the tank, allowing the pan to hang in the water without touching the anodes.
• Attach the negative (black) lead to the wire attached to the cast iron.
• Attach the positive (red) lead to the sacrificial anodes. Remember: "Red will rust."
• Turn on the battery charger and set the voltage and current to the lowest setting.

The Electrolysis Process:

• The cast iron will start to bubble in the water. Check on the pan periodically by turning off the power supply and lifting it out of the tank.
• The process is complete when all the reddish-brown rust is gone or has turned black. This can take from one hour to a day, depending on various factors.
• Place the cast iron in a sink and clean off any remaining residue with steel wool or a steel wire brush.

Important Notes:

• Electrolysis converts red rust (ferric oxide) into black rust (ferrous oxide), which is easier to remove.
• The process produces hydrogen, which is highly flammable, so ensure good ventilation.
• Avoid using stainless steel for the sacrificial anodes as it will corrode and produce carcinogenic compounds.
• Always exercise caution when working with electricity and water.

How to scrub and wash your pan

Scrubbing and washing your pan is the first step in restoring your cast iron. If your pan has a lot of rust, you can start by scouring the rusty sections with steel wool or a rust eraser. Then, wash the pan with warm, soapy water. This step may remove some of the seasoning, but that's okay, as you will be re-seasoning the pan later.

If your pan is not very rusty, you can simply wash it with water and a strong dish soap. If there are still small spots of rust, you can use sandpaper to remove them.

After scrubbing and washing, your pan will need to be dried thoroughly. Use a paper towel or lint-free cloth to completely dry the pan. You can also place it on the stovetop on low heat for a few minutes to ensure it is completely dry.

Tips for maintaining your cast iron's quality

• After each use, rub the pan with coarse kosher salt to remove cooking debris.
• Apply a thin layer of shortening or oil if desired.
• If your cast-iron cookware has a lid, always store it separately—never on top of the pan—to prevent humidity from building up and creating rust.
• Try to wash less and wipe it down more often.
• If you're making a dish that requires generating fond, use stainless cookware instead, as cast iron is not appropriate for this and won't give you good results.
• Don't cook acidic meals with long cooking times in cast iron. Frying a bunch of tomatillos in your cast-iron skillet for 5-10 minutes is fine, but leaving a tomato puree with added lemon juice in there for an hour while it simmers slowly is not a good idea, as acid will eat the seasoning.
• When you do need to wash it, just dry it off with a towel immediately (or paper towel), and put it on high heat for a little bit to get rid of any residual moisture.
• So long as it doesn't air-dry, it's going to be fine.
• Rinse with water, pad dry and put it in the oven for half an hour. Take it out, scrub again once cool, then rinse with vinegar.
• Finally, salt and scrub it all around and into the pores, then rinse the salt with veggie oil and bake.
• Repeat this process five times to build a good hardened oil layer.
• Never submerge the pan again and, after each use, dry the paper towel, salt scrub, oil, and bake it again.

Frequently asked questions