Mending The Unbreakable: Restoring Cast Iron Pans To Glory

Cast iron pans are a favourite among home cooks due to their durability, versatility and non-stick qualities. However, they are susceptible to cracking due to sudden changes in temperature or physical damage. While it may be tempting to throw away a cracked cast iron pan, there are several ways to repair it. The simplest solution is to replace the pan, especially if it's still under warranty. If you want to keep your pan, you have a few options: welding, brazing, cold metal stitching, or using an epoxy putty or metal rod product like Castaloy. While repairing your pan may be more expensive than buying a new one, it can be worth it, especially for antique or heirloom pans.

Welding

Preparation

First, you will need to clean the pan thoroughly to eliminate dirt, grease, and oxides. If the pan is rusty, use a scrub and detergent to get rid of the rust. If the pan is burnt, start by sprinkling salt on its surface, then use a scrub or soft brush to clean it. For more effective cleaning, use a damp brush. If the burn is stubborn, use a plastic scraper to remove burnt substances.

After your pan is clean and dry, you can grind it to eliminate defects and make the cracked surface ready for repair.

The stick/MMA welding process is the most popular for repairing cast iron. Cast iron rods/electrodes are readily available in small quantities, which is ideal for one-off jobs. It is critical that the weld area is very clean. Steam cleaning or hot water is often the best method, as impurities are often absorbed into the porous surface of cast iron. Clean around and on all sides of the component, not just the direct surfaces to be welded.

Vee out cracks using a rotary burr or grinding disc, often a U-shaped groove is best. Or, if butt welding pieces together, bevel the edges of the joint.

Specialist cast-iron electrodes should be used, which have a high nickel content of between 50% and 99%. Pre-heat the pan to around 120-150°C before welding.

Post-Welding

Run short weld beads (around 25mm long) at a time, to avoid overheating. Keep the current/amps setting as low as possible within the range recommended by the electrode manufacturer. Place a bead at each end of the crack, then in the middle, then stagger the rest.

Pein each weld for 1-2 minutes – using a ball pein hammer immediately after each weld bead – to help reduce the stresses induced by the contraction of the metal as it cools. If the end of the last weld is too full or lumpy, grind it back a little so you have an ideal start that will not encourage slag inclusions.

Finally, re-heat the pan to encourage an even general heat, then wrap the pan in a welding blanket or heavy rags to help retain the heat and allow the component to cool slowly.

Brazing

To braze a cracked cast iron pan, you will need to follow these steps:

• Start by cleaning the crack thoroughly to remove any dirt, grease, or debris. This can be done using a wire brush, steel wool, or a solvent.
• Next, you will need to open up the crack to prepare it for brazing. Use an angle grinder to grind out a U-shape in the metal, so it is no longer a hairline crack. This will allow the filler metal to flow into the crack and create a strong joint.
• With the crack prepared, it's time to heat the pan. Cast iron must be preheated before welding, and this can be done using a handheld propane torch or a forge. Heat the pan until it is cherry red, this will help to burn out any remaining grease or debris.
• Once the pan is hot enough, it's time to apply the filler metal. Use a brazing rod that is suitable for cast iron, such as one with a flux core that will help the metal fuse with the pan. Hold the rod against the crack and scratch it so that the filler metal melts and flows into the crack.
• Continue heating and scratching the rod until the crack is completely filled. Then, remove the heat and allow the pan to cool.
• Once the pan is cool, you can grind, shape, and polish the repaired area as needed.

It's important to note that brazing cast iron can be dangerous and should only be attempted by those with experience working with metal. Additionally, it's crucial to use food-safe metals when repairing a cast iron pan that will be used for cooking.

Epoxy putty

Step 1: Sand the Cast Iron

Use 80-grit sandpaper to sand the cast iron and remove any rust, paint, or debris covering the crack. It is important to use a back-and-forth motion instead of circular movements to avoid widening the crack. This process helps clean the surface and ensures that the epoxy will adhere properly.

Step 2: Clean the Crack

Use a rag, water, and dish soap to thoroughly clean the crack and the surrounding surface area. This step is important to remove any remaining dirt or grease. Make sure to allow the cast iron to dry completely before moving on to the next step.

Step 3: Prepare the Epoxy

Purchase a suitable epoxy putty such as JB Weld or Quick Steel from your local hardware store. Follow the manufacturer's instructions to prepare and mix the epoxy. You can use a putty knife and a flat surface, such as a scrap of cardboard, to mix it properly.

Step 4: Apply the Epoxy

Spread the prepared putty into and over the crack. Use a putty knife to scrape off any excess epoxy before it dries. It is recommended to wait for at least 24 hours for the epoxy to fully cure and harden before handling the pan again.

Step 5: Paint the Repaired Area (Optional)

Once the epoxy has cured, you can choose to paint over the sealed crack to enhance durability and ensure that the repaired area blends in with the rest of the pan. This step is optional but can help improve the appearance of your pan.

It is important to note that while epoxy putty is a convenient option for repairing a cracked cast iron pan, it is always recommended to use food-safe products and follow proper safety guidelines when working with cookware. Additionally, for larger cracks or more extensive damage, it may be more effective to seek professional repair services or consider replacing the pan altogether.

Cold metal stitching

If you're handy with metalwork, you can repair your cast iron pan using cold metal stitching. This method is best for hairline cracks, rather than a completely broken pan.

This method is superior to welding as it doesn't require any heat, which can be dangerous and cause additional stress or distortion to the cast iron. It is also a quick process, reducing downtime and avoiding the need to replace expensive cast iron items.

• Clean the crack thoroughly to ensure any dirt or debris is removed.
• Drill small holes along the crack, ensuring they are smaller than the metal keys you will be using.
• Hammer the metal keys into the holes, peening them so they become integral with the pan.
• Sand the repaired area to smooth out any bumps or rough areas.
• Re-season the pan before using it again.

This method should repair the crack in your cast iron pan, but it is important to note that it may not be as strong as it was before the crack. Always exercise caution when using a repaired pan, and consider retiring it if the crack worsens or the pan breaks further.

Drilling holes at the crack ends

Drilling Holes:

• After assessing the nature of the crack, the next step is to drill holes along the crack.
• Ensure that the holes are spaced out at regular intervals along the crack. It is recommended to use a guide for accurate drilling.
• The number of holes drilled can vary, but the goal is to create strong stitching points that will hold the cracked cast iron together.

Joining the Rows of Holes:

• Once the holes are drilled, the next step is to join them together.
• A giant chisel is used to connect the holes without creating a slot in the metal.
• The round shoulders of the drilled holes will act as holding points for the metal keys that will be inserted later.

Inserting the Metal Stitches or Keys:

• This step involves inserting metal keys or stitches, which are vital for providing strength and holding the cracked parts together.
• The drilled holes should ideally be of the same length as the metal keys to add strength across the cast iron's surface and prevent further cracks.
• Ensure a snug fit between the drilled holes and the metal keys to create a solid bond.

Sewing the Stitches Together:

• It is important to connect the inserted metal keys with screws to enhance the bond and withstand intense pressure and heat.
• Place the screws close to the neighbouring screws and metal keys.

Removing Excess Material:

• The final step is to remove any excess material from the stitching screws and metal keys using a chisel.
• Sand down the remaining excess material with a grinding tool to restore the cast iron piece to its original state, hiding any evidence of repair.

Remember, repairing cast iron without welding requires careful execution of these steps to ensure a solid and durable repair.

Frequently asked questions