How to Clean Rusty Coins Safely and Effectively
Cleaning rusty coins is a delicate process. While a shiny, clean coin might seem desirable, improper cleaning can severely damage the coin’s surface, reducing its value and historical significance. The goal isn’t always to make a coin look brand new, but rather to remove loose rust and stabilize the coin to prevent further deterioration. This article provides a comprehensive guide on how to clean rusty coins safely and effectively, covering various methods and precautions to ensure you don’t inadvertently destroy a potentially valuable or historically important artifact.
## Understanding the Risks Before You Start
Before diving into cleaning methods, it’s crucial to understand the risks involved. Coins are valued based on their condition, and collectors generally prefer coins with original surfaces, even if they’re tarnished. Aggressive cleaning methods can scratch the surface, remove the original patina, or even wear away the metal, significantly reducing the coin’s numismatic value. In some cases, a coin that appears rusty might actually have a valuable and desirable toning. Therefore, consider the following before you begin:
* **Value:** Is the coin valuable? If so, consider consulting a professional coin dealer or numismatist. They can assess the coin and advise on the best course of action. Cleaning a valuable coin improperly can make it worthless.
* **Material:** What is the coin made of? Different metals react differently to cleaning agents. Silver, copper, nickel, and other metals require specific approaches.
* **Type of Rust:** Is it light surface rust or deep, embedded corrosion? Light rust might be removable with gentle methods, while severe corrosion may require more aggressive techniques, which should only be attempted with extreme caution and ideally by a professional.
* **Desired Outcome:** What are you hoping to achieve? Are you simply trying to remove loose dirt and rust to make the coin more presentable, or are you aiming for a pristine, like-new appearance? Remember, the latter is often detrimental to a coin’s value.
**Rule of Thumb: Less is More.** Always start with the gentlest method possible and only escalate if necessary. Once damage is done, it cannot be undone.
## Essential Supplies for Cleaning Coins
Before you begin cleaning, gather the following supplies. Having everything on hand will make the process smoother and prevent you from using inappropriate substitutes.
* **Soft Cloths:** Use lint-free microfiber cloths for wiping and drying coins. Avoid abrasive materials that can scratch the surface.
* **Soft-Bristled Brushes:** A soft toothbrush, artist’s brush, or specialized coin cleaning brush can be used to gently remove loose dirt and rust. Ensure the bristles are soft enough to avoid scratching.
* **Distilled Water:** Use distilled water for rinsing coins, as tap water can contain minerals and chemicals that can leave deposits.
* **Cotton Swabs:** Useful for applying cleaning solutions and gently removing debris from small areas.
* **Magnifying Glass:** A magnifying glass will help you examine the coin’s surface closely and identify areas that need attention.
* **Coin Holders or Albums:** Once cleaned, store your coins properly to prevent further corrosion. Use acid-free coin holders, albums, or sleeves.
* **Optional: Olive Oil or Mineral Oil:** These can be used for soaking coins to loosen rust.
* **Optional: Baking Soda:** A mild abrasive that can be used to create a paste for gentle cleaning.
* **Optional: Lemon Juice or Vinegar:** Diluted solutions can be used to remove rust, but use with extreme caution and only on certain metals.
* **Optional: Commercial Coin Cleaning Solutions:** These are specifically formulated for cleaning coins, but read the instructions carefully and use with caution.
## Gentle Cleaning Methods: Starting with the Basics
Always begin with the gentlest methods and gradually increase the intensity only if necessary. These methods are suitable for removing loose dirt and light surface rust.
### 1. Distilled Water Soak
This is the safest and often the most effective first step. Simply soak the coin in distilled water for several hours or even overnight.
* **Procedure:**
1. Fill a small, clean container with distilled water.
2. Place the rusty coin in the water, ensuring it’s fully submerged.
3. Let the coin soak for several hours or overnight.
4. After soaking, gently rinse the coin under running distilled water.
5. Use a soft-bristled brush to gently remove any remaining loose dirt or rust.
6. Pat the coin dry with a soft, lint-free cloth.
* **Why it Works:** Soaking in distilled water helps to loosen dirt and rust without using any harsh chemicals or abrasives.
### 2. Soap and Water
If distilled water alone isn’t enough, you can add a mild soap to the water.
* **Procedure:**
1. Fill a small container with distilled water.
2. Add a few drops of mild dish soap (avoid detergents with harsh chemicals or dyes).
3. Place the rusty coin in the soapy water.
4. Let the coin soak for 30 minutes to an hour.
5. Gently scrub the coin with a soft-bristled brush.
6. Rinse the coin thoroughly under running distilled water to remove all traces of soap.
7. Pat the coin dry with a soft, lint-free cloth.
* **Why it Works:** The soap helps to break down surface oils and grime, making it easier to remove dirt and rust.
### 3. Olive Oil or Mineral Oil Soak
Olive oil and mineral oil can be effective for loosening stubborn rust. These oils penetrate the rust and help to lift it away from the coin’s surface.
* **Procedure:**
1. Place the rusty coin in a small container.
2. Cover the coin completely with olive oil or mineral oil.
3. Let the coin soak for several days or even weeks. The longer the soak, the better the results.
4. After soaking, gently remove the coin from the oil.
5. Use a soft-bristled brush to gently scrub the coin under running distilled water.
6. If necessary, repeat the soaking and scrubbing process.
7. Once the rust is removed, rinse the coin thoroughly with distilled water and pat it dry with a soft, lint-free cloth.
* **Why it Works:** The oil penetrates the rust, weakening its bond with the coin’s surface. The gentle scrubbing helps to remove the loosened rust.
## More Aggressive Cleaning Methods: Use with Caution
These methods involve using mild abrasives or chemicals and should only be used if the gentle methods have failed and if you understand the risks. Always test these methods on a small, inconspicuous area of the coin first.
### 4. Baking Soda Paste
Baking soda is a mild abrasive that can be used to create a paste for gentle cleaning. However, it can still scratch the surface of the coin, so use it sparingly and with caution.
* **Procedure:**
1. Mix a small amount of baking soda with distilled water to form a thick paste.
2. Apply the paste to the rusty areas of the coin.
3. Gently rub the paste on the coin’s surface using a soft cloth or cotton swab. Avoid applying too much pressure.
4. Rinse the coin thoroughly under running distilled water to remove all traces of baking soda.
5. Pat the coin dry with a soft, lint-free cloth.
* **Why it Works:** The mild abrasive action of baking soda helps to remove rust and dirt from the coin’s surface. However, be careful not to scrub too hard, as this can scratch the coin.
### 5. Lemon Juice or Vinegar Soak (Use with Extreme Caution)
Lemon juice and vinegar are acidic and can dissolve rust. However, they can also damage the coin’s surface if used improperly. These methods are best reserved for heavily corroded coins and should be used with extreme caution.
* **Important:** Before using lemon juice or vinegar, identify the metal of the coin. These methods are generally **not recommended** for copper or bronze coins, as they can cause further corrosion. They may be used with extreme care on silver coins, but test a small area first.
* **Procedure:**
1. Dilute the lemon juice or vinegar with distilled water. Start with a weak solution (e.g., 1 part lemon juice/vinegar to 10 parts water) and gradually increase the concentration if necessary.
2. Place the rusty coin in the diluted solution.
3. Let the coin soak for a very short period (e.g., 1-2 minutes). Monitor the coin closely and remove it immediately if you see any signs of damage or discoloration.
4. Rinse the coin thoroughly under running distilled water to remove all traces of the acid.
5. Neutralize the acid by soaking the coin in a solution of baking soda and water for a few minutes.
6. Rinse the coin again with distilled water.
7. Pat the coin dry with a soft, lint-free cloth.
* **Why it Works:** The acid in lemon juice or vinegar dissolves the rust. However, it can also dissolve the coin’s metal, so it’s crucial to use a diluted solution and monitor the coin closely.
### 6. Commercial Coin Cleaning Solutions
There are several commercial coin cleaning solutions available that are specifically formulated for removing rust and tarnish. These solutions can be effective, but it’s essential to read the instructions carefully and use them with caution.
* **Procedure:**
1. Read the instructions on the coin cleaning solution carefully.
2. Apply the solution to the rusty areas of the coin according to the instructions.
3. Let the solution sit for the recommended amount of time.
4. Rinse the coin thoroughly under running distilled water to remove all traces of the solution.
5. Pat the coin dry with a soft, lint-free cloth.
* **Why it Works:** Commercial coin cleaning solutions contain chemicals that dissolve rust and tarnish. However, they can also damage the coin’s surface if used improperly, so it’s crucial to follow the instructions carefully.
## Methods to AVOID
Certain cleaning methods are almost guaranteed to damage your coins. Avoid these at all costs:
* **Harsh Abrasives:** Steel wool, sandpaper, scouring pads, and other harsh abrasives will scratch the coin’s surface and ruin its value.
* **Strong Chemicals:** Bleach, hydrochloric acid, and other strong chemicals can corrode the coin’s metal and cause irreversible damage.
* **Polishing Machines:** Polishing machines can remove the coin’s surface details and leave it with an unnatural shine.
* **Ultrasonic Cleaners:** While sometimes used for other delicate objects, the vibrations and solutions used in ultrasonic cleaners can damage coins, especially those with loose corrosion.
## After Cleaning: Preservation and Storage
Once you’ve cleaned your coins, it’s important to store them properly to prevent further corrosion. Here are some tips:
* **Handle Coins Carefully:** Always handle coins by the edges to avoid transferring oils from your fingers to the coin’s surface.
* **Use Acid-Free Coin Holders:** Store your coins in acid-free coin holders, albums, or sleeves. These materials will not react with the coin’s metal and will help to protect it from corrosion.
* **Control Humidity:** Store your coins in a cool, dry place. High humidity can accelerate corrosion.
* **Avoid Direct Sunlight:** Direct sunlight can cause the coin’s surface to fade or discolor.
* **Desiccants:** Consider using desiccants in your coin storage area to absorb moisture and prevent corrosion.
## When to Seek Professional Help
If you’re unsure about how to clean a particular coin, or if the coin is valuable, it’s best to seek professional help from a coin dealer or numismatist. They have the knowledge and experience to clean coins safely and effectively without damaging them.
## Identifying Coin Metals
Knowing the metal composition of your coin is crucial for selecting the appropriate cleaning method. Here’s a brief overview of common coin metals:
* **Copper:** Often reddish-brown in color. Can corrode easily, forming a green or blue patina.
* **Bronze:** An alloy of copper and tin. Similar in appearance to copper but slightly more durable.
* **Nickel:** Silvery-white in color. Resistant to corrosion but can tarnish over time.
* **Silver:** Shiny and silvery-white. Can tarnish easily, forming a black or gray sulfide layer.
* **Gold:** Yellow and lustrous. Highly resistant to corrosion.
* **Zinc:** A dull gray metal that is often plated. Very susceptible to corrosion.
* **Steel:** Typically plated with another metal, prone to rusting if the plating is damaged.
If you are unsure of the metal composition of a coin, consulting a coin catalog or expert is recommended before attempting any cleaning methods.
## Final Thoughts
Cleaning rusty coins is a task that requires patience, care, and a thorough understanding of the risks involved. Always start with the gentlest methods and only escalate if necessary. Remember that the goal is to remove loose rust and stabilize the coin, not necessarily to make it look brand new. By following these guidelines, you can clean your rusty coins safely and effectively, preserving their value and historical significance. If a coin is particularly valuable or historically important, consulting a professional is always the safest option.
Remember to always document the condition of the coin before and after cleaning. This can be helpful for insurance purposes and for tracking the effectiveness of your cleaning methods.