How To Parkerize Metal: A Comprehensive Guide

Understanding the Parkerizing Process

What is Parkerizing?

The deep, dark grey finish of Parkerizing is instantly recognizable, a hallmark of durability and understated elegance. More than just an aesthetic choice, Parkerizing offers a robust layer of protection against corrosion, enhancing the longevity and performance of the metal it coats. Whether you’re a dedicated firearm enthusiast restoring a classic piece, a DIY enthusiast looking to learn a new skill, or a restorer breathing new life into vintage machinery, mastering the art of Parkerizing can be a rewarding and practical endeavor. This guide provides a comprehensive walkthrough, offering everything you need to know to safely and effectively achieve professional-quality results.

Types of Parkerizing

The fundamental goal of Parkerize Metal is to create a protective layer of iron phosphate (typically manganese or zinc) on the surface of a metal object, usually steel or iron. This conversion coating changes the metallic surface, offering superior resistance to rust and wear. The process itself involves a controlled chemical reaction where the metal object is submerged in a heated phosphoric acid-based solution. This solution, carefully formulated with specific additives, reacts with the metal surface to form a layer of insoluble metal phosphates. This porous layer then readily absorbs oils, creating a highly effective barrier against the elements. The result is a matte, dark grey finish that provides superior corrosion protection compared to bare metal.

Parkerizing solutions primarily come in two main types: manganese phosphate and zinc phosphate. Manganese phosphate Parkerizing is the most common type, and is what we’ll focus on for this guide. This process delivers excellent corrosion resistance and is known for its durability, commonly used in firearms and automotive applications. Zinc phosphate, on the other hand, is often chosen for its ability to provide a slightly finer finish and is frequently used for parts which will be painted afterward.

Regardless of the specific type of Parkerizing solution used, safety is of paramount importance. The chemicals involved can be hazardous if handled improperly. Always wear appropriate personal protective equipment (PPE), including chemical-resistant gloves, eye protection, and a well-ventilated workspace to avoid inhaling fumes.

Gathering the Necessary Materials and Tools

Chemicals

To successfully Parkerize Metal, you’ll need to assemble the right materials and equipment. This section outlines the essentials.

Parkerizing Solution: The core of the process. Choose a manganese or zinc phosphate solution based on the needs of your project. Purchase a solution specifically formulated for Parkerize Metal applications. The solution should be of good quality and recommended by a reputable manufacturer.
Degreaser: Metal parts must be completely free of grease, oil, and other contaminants. A strong degreasing agent is essential. Common options include alkaline degreasers or solvent-based degreasers. Select a product that is safe for the metal you’re working with and follow the manufacturer’s instructions carefully.
Rinse Water: Clean water is crucial to remove any residual chemicals between steps. Distilled or deionized water is strongly recommended. Using clean water minimizes the risk of contamination that can negatively impact the finished result.
Rust Remover (optional): If the metal parts have rust, a rust remover is necessary before the Parkerizing process. This will ensure the Parkerizing solution can properly adhere to the base metal. Select a rust remover that is safe for the metal being treated and follow the manufacturer’s instructions.
Optional Chemicals: Some projects may benefit from pre-treatment solutions such as those to improve surface preparation.

Equipment

Tank(s): You’ll need dedicated tanks to hold the solutions for each step: degreasing, rinsing, parkerizing, and potentially, a post-treatment oil. The size of the tanks will depend on the size of the metal parts you intend to process. Plastic tanks are usually ideal because of their resistance to the chemicals. Make sure your tanks are robust enough to withstand heat, if required.
Heat Source: A heat source is required to heat the Parkerizing solution. A hot plate or an immersion heater specifically designed for chemical baths works well. Ensure the heat source is capable of maintaining the temperature recommended by the Parkerizing solution manufacturer.
Thermometer: A reliable thermometer is essential for monitoring the temperature of the Parkerizing solution and the degreasing solutions. Precise temperature control is critical to the success of the Parkerizing process.
Hanging Wires or Racks: You will need a method to suspend the metal parts within the tanks without them touching the bottom or each other. Stainless steel wire or custom-built racks are great options. Make sure your hanging method leaves sufficient space for the chemicals to react.
Gloves: Essential for protecting your hands from chemicals. Use chemical-resistant gloves that are appropriate for the chemicals you are using. Nitrile gloves are a good general-purpose choice.
Eye Protection: Safety glasses or goggles are essential to protect your eyes from splashes and fumes.
Ventilation System: Parkerizing can generate fumes. A well-ventilated workspace is vital, particularly when working indoors. Ensure adequate air circulation. Consider using a fume hood.
Timer: A timer helps keep track of the immersion times during the various steps of the process.
Measuring Tools: Accurate measurement of chemicals is essential. You’ll need measuring cups or graduated cylinders for the various solutions.

Metal Parts Preparation

Parts Selection: Parkerizing is most effective on steel and iron. Avoid using it on non-ferrous metals like aluminum or brass without careful consideration and specialized pre-treatment solutions.
Disassembly: If applicable, disassemble any parts that need to be Parkerize Metal and remove any non-metal components.
Degreasing: Before Parkerizing, every part must be thoroughly degreased to remove any oil, grease, or dirt. This will allow the parkerizing solution to react effectively with the bare metal.
Rust Removal (if applicable): If any rust is present, you will need to remove it. There are different methods of removing rust, from chemical rust removers to abrasive methods like bead blasting.
Surface Preparation (optional): For the best results, consider lightly abrasive blasting the surface of the metal parts. This will remove any existing coatings, and create a surface that is more receptive to the Parkerizing process.

The Parkerizing Process: Step-by-Step Guide

Following the steps outlined below meticulously will help you consistently achieve excellent results when you Parkerize Metal.

Degreasing

Degreasing is the first and most critical step. Without proper degreasing, the Parkerizing solution will not adhere evenly, if at all.
Method: Submerge the metal parts in the degreasing solution. Follow the manufacturer’s recommendations for the temperature and time. Monitor the parts to ensure they are fully submerged and that the solution is effectively removing grease.
Rinsing: After degreasing, thoroughly rinse the parts in clean water, preferably distilled or deionized, to remove any residual degreaser.

Rust Removal (if applicable)

If the metal parts have any rust, this is the next necessary step.
Method: Submerge the metal parts in the rust-removing solution. The amount of time the parts will be in the rust removing solution will vary based on the solution and the severity of the rust. Follow the manufacturer’s instructions. Inspect the parts periodically to ensure the rust is removed without damaging the underlying metal.
Rinsing: After rust removal, rinse the parts thoroughly in clean water.

Rinsing

Rinsing is absolutely vital between each step. It eliminates contamination from one process to the next, which could impede the parkerizing process.
Method: Submerge the metal parts in clean water. Make sure all traces of the previous chemical process are thoroughly rinsed.
Water Type: Use distilled or deionized water for rinsing.

Parkerizing

This is the core of the process.
Setup: Carefully prepare the Parkerizing solution according to the manufacturer’s instructions. This often involves adding water to a concentrated solution. Heat the solution to the recommended temperature.
Immersion: Suspend the degreased and rinsed metal parts in the Parkerizing solution using the hanging wires or racks. Make sure the parts are completely submerged and not touching each other or the bottom of the tank.
Time and Temperature: Follow the manufacturer’s guidelines for immersion time and temperature. These factors are critical for achieving the desired finish and level of corrosion resistance. For manganese phosphate, the typical temperature range is between 190°F and 200°F (88°C and 93°C), and the typical immersion time is 20-30 minutes. Zinc phosphate processes have different recommendations, so consult the directions for the solution you are using.
Monitoring: Monitor the process. You should see the metal surface reacting with the solution, resulting in the formation of a matte, dark grey coating.
Agitation: Gently agitating the solution (optional) can help promote even coating.
Removed Parts: After the recommended time has elapsed, carefully remove the metal parts from the Parkerizing solution.

Rinsing (again)

Rinse the Parkerized parts again in clean water. This removes any residual Parkerizing solution.

Post-Treatment/Oiling

This step is essential for protecting the Parkerized finish and maximizing its corrosion resistance.
Oiling: Submerge the Parkerized parts in a protective oil. Alternatively, apply oil to all surfaces using a spray or brush. The oil saturates the porous Parkerized layer, helping it to resist moisture and other corrosive agents.
Types of Oil: Use a high-quality oil specifically designed for this purpose. Gun oils are often appropriate for firearms, while other types of industrial oils may be more suited for other applications.
Drying and Curing: After oiling, allow the parts to dry and cure completely. This usually involves letting the parts drain and then wiping off any excess oil.

Troubleshooting Common Parkerizing Problems

Even with meticulous execution, problems can arise. Here’s how to address some common issues:

Uneven Finish

This can be caused by several factors, including improper degreasing, uneven solution temperature, or the presence of contaminants. Ensure thorough degreasing, monitor the temperature, and use clean solutions.

Poor Corrosion Resistance

This can be a result of insufficient Parkerizing time, inadequate oiling, or using contaminated solutions. Extend the Parkerizing time if the coating is too thin, ensure complete oil saturation, and replace contaminated solutions.

Flaking or Peeling Finish

This may indicate improper surface preparation, an incorrect solution concentration, or immersion time. Re-blast the metal parts to provide a new surface for the coating to adhere to. Ensure the solution concentration is correct and follow recommended immersion times.

Color Variations

The color of the finished product can vary based on the temperature, the specific composition of the solution, the type of steel, and the time in the solution. Variations are often within acceptable ranges, but if the results are far from desirable, ensure a consistent temperature, proper solution concentration, and follow the process precisely.

Maintaining Your Parkerized Finish

Once you’ve successfully Parkerize Metal, proper maintenance will ensure the finish remains durable.

Cleaning Techniques

When cleaning, use a mild soap and water solution or a dedicated metal cleaner. Avoid abrasive cleaners that can damage the surface.

Oiling Schedule

Regularly re-oil the Parkerized parts, particularly in environments where corrosion is a risk. This helps to maintain the protective properties of the coating. The frequency depends on the use and the environment to which the object is exposed.

Long-Term Storage

Before long-term storage, thoroughly clean and oil the parts. Store them in a dry environment to prevent moisture from causing corrosion.

Touch-up Techniques

For minor scratches or wear, you can re-oil the affected areas. For more significant damage, the area may need to be re-parkerized.

Advanced Considerations

Parkerizing provides an excellent base for Cerakote application. The matte, porous surface of a Parkerized finish aids in adhesion, leading to a durable, long-lasting finish.

If you’re Parkerizing metal parts, particularly firearms, make sure that the Parkerizing process is legal and compliant with all local, state, and federal laws.

Conclusion

The process of Parkerize Metal is a journey that combines scientific principles with careful craftsmanship. From selecting the right chemicals and tools to following precise steps, the detailed guidelines and suggestions in this article will help you to achieve professional results. Remember to prioritize safety and take your time to understand each step. With practice, you can master this valuable skill and enjoy the lasting benefits of a beautifully Parkerized finish.

When you’re ready to embark on your Parkerizing project, make sure that you are purchasing quality materials, and follow all of the safety precautions to help ensure that you will have great results. Good luck, and happy Parkerizing!