What Materials Cannot Be Powder Coated?

Powder coating is a durable, high-quality alternative to paint for finishing automobile parts, furniture, and many other products and components. However, the best finishing solution for a part depends on its material. While powder coating is effective for many of the manufacturing sector’s most popular metals, some materials are less compatible with powder coating. If you have a component that needs finishing, this guide will help you determine whether powder coating will work.

What Is Powder Coating?

Powder coating involves electrostatically charging powder particles and blasting them at a metal surface with an electrostatic spray gun or other tool. The electrostatic charge allows the powder to stick to the surface. After that, you cure the finish in a heated oven, where the powder melts to form an even coat.

Benefits of Powder Coating

Advantages of this finishing method include:

• Durability: Powder coating can last well over a decade and helps a component resist corrosion, chips, and scratches.
• Sustainability: Compared to other finishing methods, powder coating minimizes pollution from volatile compounds. It also reduces industrial waste, as overspray is reusable.
• Cost-effectiveness: This is a quick, efficient finishing method that helps reduce costs, especially at scale.
• Quality: Powder coating is an ideal solution for a thick, even finish with a wide range of color and pattern possibilities.

Powder Coating Applications

Powder coating is a popular finishing method for:

• Automobile parts
• Industrial machinery
• Indoor and outdoor furniture
• Electronics and appliances
• Pipes
• Sport and exercise equipment

What Will Powder Coat Not Stick to?

While powder coating is a versatile finishing method compatible with many different materials, its reliance on electrostatic bonds and high heat creates some limitations. Ordinary powder coating processes encounter obstacles when applied to nonconductive, heat-sensitive, and porous materials.

Nonconductive Materials

A material must be conductive for electrostatic bonds to stick the powder coat to its surface. This creates challenges for materials like: 

• Plastics: Plastic is an insulator, preventing electrostatic bonds from forming on its surface. Overcoming this challenge requires using a pretreatment like a conductive primer or other, more expensive powder coating methods engineered to work on plastics. 
• Wood: Wood has poor conductive properties. A more suitable wood-like alternative for powder coating is medium-density fiberboard (MDF). Woods with a moisture level of 5%-7% can also work because the moisture is conductive. 
• Glass: Glass lacks the natural conductivity for powder coating, though conductive pretreatments can help address this issue. Sandblasting can help prepare a glass surface for powder coating.

Heat-Sensitive Materials

Powder coat curing temperatures can reach 400 degrees Fahrenheit and sometimes hotter. Before starting a powder coating job, it’s vital to check that the material can withstand these extreme temperatures. This poses difficulties for:

• Plastics: Most plastics melt at standard powder coat curing temperatures. Exceptions include polysulfone, polyetherimide, and polyphenylene, which offer superior heat resistance. For heat-sensitive plastics, ultraviolet (UV) curing eliminates the need for extreme temperatures, though not all facilities have the tools and knowledge to apply this method. Alternatively, facilities can use special coatings that cure at lower temperatures.
• Wood: Most wood is vulnerable to high temperatures. Finishers should opt for a composite like MDF or use lower-temperature curing techniques.
• Glass: High heat can crack or melt regular glass. Only tempered or other specialty glasses designed to withstand heat can survive the curing process.

Porous Materials

Porous and absorbent materials don’t suit powder coating. The finish could end up uneven, as the surface will absorb some of the coating and make it difficult for strong adhesive bonds to form. During curing, porous materials can release trapped air or gases, causing coating defects like bubbles. Wood and concrete are prone to these issues. If powder coating a porous material is necessary, the best ways to minimize these issues are by pretreating the surface and using UV or other lower-temperature curing techniques.

What Materials Can Be Powder Coated?

Although some materials present significant challenges for powder coating, standard powder coating methods work well for many materials. The best results come with materials that can hold an electrostatic charge and tolerate extreme heat from curing. Aluminum, steel, iron, and zinc are four ideal materials for powder coating.

1. Aluminum

Aluminum is conductive and can withstand temperatures up to 1220 degrees Fahrenheit without melting. Powder-coated aluminum is used for:

• Window frames
• Bicycle frames
• Aerospace components

Since aluminum is a relatively porous metal and vulnerable to oxidization, it requires thorough cleaning and preparation before powder coating.

2. Steel

Steel is strong, conductive, and heat-resistant. Powder coating enhances its resistance to chemicals and corrosion while adding an attractive finish.

Powder-coated steel is used for automotive parts and heavy machinery. These applications use various kinds of steel and steel alloys, including:

• Galvanized steel
• Stainless steel
• Mild steel
• Electroplated steel
• Carbon steel

3. Iron

Iron, including cast and wrought iron, is compatible with powder coating after preparation and pretreatment. Powder coating forms a durable, corrosion-resistant finish for iron products like outdoor furniture and stair railings.

4. Zinc

Zinc alloys provide a reliable, adhesive, and heat-resistant base for powder coatings. Sandblasting and primer application can help prepare a zinc surface for an optimally durable and attractive finish. Powder-coated zinc is useful for:

• Metal roofing
• Air ducts
• Agricultural machinery
• Electrical component housings

Can You Powder Coat Over All Metals?

You can powder coat most metals with proper preparation, but some metals present more challenges than others. For example:

• Lead is toxic, making it unsuitable for most industrial and consumer purposes.
• Titanium has poor conductivity, making it difficult for a regular powder coat to adhere.
• Copper is very heat-sensitive, increasing the risk of an uneven cure. 

4 Tips for Those New to Powder Coating

Material selection is just one part of a successful powder coating job. If you’re a new powder coater, these tips will help you build a reputation in the business for producing the finish possible every time:

1. Know your material: Choose conductive and heat-resistant metals. If you need to use a material like glass or ceramic, make sure you understand its properties and whether you’ll need to use any special pretreatment or curing approaches.
2. Control for quality: Implement powder coating quality control tests. These tests could include using a film thickness gauge to test coating thickness and adhesion testing through mandrel bends or impact testing.
3. Prepare your surface: Surface preparation is essential for a quality powder coat finish. To ensure evenness and durability, use high-quality abrasives to sandblast a surface before applying the powder coat.
4. Follow your industry: Read blogs and industry publications to stay current with the latest developments and best practices in powder coating.

Trust 10X Engineered Materials for Sandblasting Materials

No matter the material you’re powder coating, how you prepare it will impact the quality of finish you can produce. Abrasive blasting gives you a clean canvas to create a powder coated masterpiece. Choose 10X Engineered Materials as your sandblasting abrasives partner and experience the following benefits:

• Safety: Superoxalloy products are the only biosoluble abrasives on the market. This means any particles that enter the body can dissolve naturally without causing harm. By choosing our superoxalloy abrasives, you avoid the persistent carcinogenic particles that other abrasives launch into the air around you.
• Quality: Our superoxalloy sandblasting abrasives are precision-engineered to produce a pristine and ready-to-coat surface.   
• Value: Engineered to create a ready-to-coat surface in a single step with less abrasive for the same job, 10X superoxalloy abrasives are incredibly cost-effective.
• Speed: Superoxalloy sandblasting abrasives are the fastest-acting in the industry and can accomplish complete surface preparation in a single blast.
• Support: You can contact us for free technical support in choosing and using sandblasting abrasives for powder coating projects.

Make an engineered decision. Contact us today to discover the ideal abrasives for your next powder coating project.