Rust forms when iron reacts with oxygen and water causing that familiar orange and brown flaking also known as iron oxide.
So, it will come as no surprise that untreated cast iron can rust over time, especially when left wet. Knowing the proper method for cleaning cast iron is important to prevent rust and maintain its appearance over time. Cast iron is an incredibly versatile material with a wide range of applications that can be susceptible to rust, from cookware like pans and skillets to ornamental metalwork, gates and fireplaces.
When determining how to clean cast iron, it’s important to consider the item’s age and whether the metal surface is painted or exposed. This will ensure that you use the appropriate cleaning techniques.
For instance, unless it’s enamelled, cast iron pans and skillets are meant to have exposed surfaces that are seasoned with oil. Fireplaces and stoves often have protective finishes like iron paste or paint to safeguard their surfaces, while exterior metalwork is typically painted.
If cast iron does become wet, it is crucial to ensure that the metal dries completely before undertaking any refinishing or painting tasks, this will ensure that rush does not form underneath the protective layer you are adding.
When dealing with rust, it is advisable to use a wire brush or wire wool for removal. However, exercise caution when considering the use of mechanical tools, especially on delicate or decorative surfaces, as they may result in damage.
For cast iron antique and heritage items that are heavily worn or rusted, or if you are unsure about the proper cleaning methods, it is recommended to seek the services of a professional restorer like Cast Iron Welding Services. We are experts cast iron restoration and will be able to advise you on the best methods to restore your cast iron piece.
Methods and Tips for Cast Iron Restoration
Unseasoned or unfinished cast iron is prone to rapid rust formation, particularly in humid conditions. Fortunately, cleaning rust from cast iron is a relatively straightforward process that can be achieved using wire wool or a wire brush. While wearing protective clothing, simply apply circular motions over the rusty areas until the rust is effectively removed.
Once the rust has been eliminated from the cast iron, it is advisable to refinish or re-season the surface to prevent future rusting.
Refinishing Painted Cast Iron: Steps and Safety Precautions
If the painted cast iron is in good condition, with no flaking paint, a simple damp cloth can be used for cleaning. However, when the paint is peeling, revealing rust beneath, it becomes necessary to strip it down and refinish the surface.
It’s important to ensure that all loose paint and rust are thoroughly removed. Not all the existing paint may require removal; in some cases, you can prepare corroded areas and then spot paint them. Sound paint can be cleaned, and sanded to provide a suitable surface, and used as a base for applying new paint. Again this is dependent on the paint used previously.
It’s important to be aware that older paints often contained lead, so it’s wise to use a test kit to check for lead presence before sanding, as sanding can create hazardous dust particles. If lead is detected, opt for methods that do not generate dust or fumes, such as a solvent or caustic-based liquid stripper, and ensure you use appropriate protective gear. If you are uncertain, it’s advisable to seek professional guidance, from experts like Cast Iron Welding. Our team will be able to assess your cast iron and advise of the best route forward to restore your cast iron.