Last updated on August 28th, 2026 at 09:51 am
Powder coating and wet paint are two common finishing options for custom sheet metal parts, but neither is automatically the better choice for every application.
The right finish depends on the service environment, cosmetic requirements, coating specification, color, dimensional requirements, electrical conductivity, assembly sequence, and whether the part can tolerate the required curing process.
Approved Sheet Metal offers in-house powder coating and can coordinate wet paint through outside finishing partners. Here is what mechanical engineers and buyers should consider when choosing between the two.
Powder Coat vs. Wet Paint: What’s the Difference?
| Consideration | Powder Coat | Wet Paint |
|---|---|---|
| Application | Dry powder applied electrostatically and cured using heat | Liquid coating applied to the part and cured or dried according to the coating system |
| Colors | Extensive color selection | Extensive color selection |
| Textures | Wide range of textures and gloss levels | Depends on the coating system |
| Coating Build | Typically produces a measurable coating build that must be considered at close-fitting features | Coating thickness depends on the specified paint system |
| Cure Temperature | Requires an elevated-temperature cure cycle | Depends on the specified coating system |
| Multiple Colors | Possible, but additional masking and processing can add complexity | Often offers greater flexibility for complex multi-color requirements |
| Touch-Up | Can be difficult to blend seamlessly depending on the finish | May be easier to touch up depending on the coating system |
| Electrical Contact | Typically electrically insulating and may require masking | Depends on the coating system |
| ASM Processing | Available in-house | Coordinated through outside finishing partners |
What Is Powder Coating?
Powder coating is a dry finishing process in which electrically charged powder is sprayed onto a conductive metal part. The powder adheres to the surface, and the coated part is then heated so the powder flows and cures into a continuous finish.
Powder coatings are available in a wide variety of colors, textures, and gloss levels and are commonly used on fabricated aluminum and steel components, including enclosures, brackets, panels, covers, frames, and other sheet metal parts.
Specifying Powder Coat Color and Appearance
A callout such as “powder coat black” leaves a significant amount of room for interpretation. There are many different blacks, gloss levels, textures, and powder formulations.
A RAL number can be used to identify a standardized color, but the RAL number alone does not necessarily define the powder manufacturer, product, gloss, or texture.
When appearance is important, specify as much of the following information as applicable:
- Color or RAL number
- Gloss level
- Texture
- Powder manufacturer and product number if required
- Cosmetic surface requirements
- Approved color sample if matching an existing product is critical
For additional design considerations, see our guide to designing powder-coated sheet metal parts.
Benefits of Powder Coating
Powder coating can provide a durable and attractive finish with extensive color and texture options. Depending on the coating system and pretreatment, it can also provide corrosion and wear protection for fabricated metal components.
For qualifying projects, ASM’s in-house powder coating capability can also reduce the need to send parts to an outside finishing supplier, which can help simplify the manufacturing flow.
Actual cost and lead time depend on the powder specification, pretreatment, masking, quantity, color, part size, geometry, and other project requirements.
Limitations of Powder Coating
Powder coating requires an elevated-temperature cure cycle, which needs to be considered when the finished assembly contains temperature-sensitive components.
Some plastics, adhesives, seals, inserts, and other components may not tolerate the required cure temperature and may need to be installed after finishing.
Multiple colors, detailed masking, graphics, or complex cosmetic requirements can also increase processing complexity. In some of these applications, wet paint may provide greater flexibility.
What Is Wet Paint?
Wet paint uses a liquid coating that is sprayed or otherwise applied to the metal surface. The exact process depends on the specified coating system and may include surface preparation, primer, one or more coating layers, and a defined drying or curing process.
Wet paint is available in a wide variety of colors, sheens, and coating chemistries. Color may be specified using a RAL number, another color standard, a coating manufacturer’s product number, a customer-specific specification, or an approved physical sample.
Benefits of Wet Paint
Wet paint can be a good option when a project requires:
- A customer-specified paint system
- A specialized coating chemistry
- Complex multi-color finishing
- A legacy color or existing product match
- A coating system with specific environmental requirements
- Touch-up or repair considerations
- A part or assembly that cannot tolerate the required powder-coat cure cycle
Wet paint can also provide more flexibility when a drawing or customer specification already defines the exact coating system that must be used.
Limitations of Wet Paint
Depending on the coating system, wet paint may require multiple application, drying, or curing steps. This can increase processing time compared with some powder-coating applications.
At ASM, wet paint is also an outside process, while powder coating is available in-house. The resulting cost and lead-time difference depends on the specific project and coating requirements.
Designing Sheet Metal Parts for Powder Coat or Wet Paint
Choosing the coating is only part of the engineering decision. The design also needs to account for how that coating will affect the finished part.
Important considerations include coating buildup, masking, grounding, hardware installation, hanging or fixturing, drainage, cosmetic surfaces, and assembly fit.
Account for Coating Buildup
Powder coating and wet paint both add material to the surface of a part. The actual coating thickness depends on the finish specification and application process.
This buildup becomes particularly important around:
- Close-fitting mating parts
- Holes and slots
- Tabs and locating features
- Sliding interfaces
- Enclosure covers and lids
- Press-fit features
- Hardware interfaces
- Other dimensionally sensitive surfaces
Do not assume that a close-fitting assembly that works before finishing will have the same clearance after coating.
If a feature has a critical finished dimension or fit, identify that requirement on the drawing so the coating and masking requirements can be considered during manufacturing.
Identify Masked Areas on the Drawing
Not every surface should necessarily receive coating.
Depending on the application, masking may be required at:
- Grounding points
- Electrical bonding surfaces
- Critical mating surfaces
- Threads
- Press-fit locations
- Close-tolerance interfaces
- Hardware interfaces
- Other areas where coating would interfere with function
Clearly identify these areas on the drawing rather than relying on the finisher to determine which surfaces should remain uncoated.
Consider Grounding and Electrical Contact
Standard powder coating is electrically insulating. If the sheet metal part is part of an electrical grounding or bonding path, the required contact surfaces may need to remain free of coating.
This can affect enclosure grounding points, mounting locations, hardware interfaces, doors, removable panels, and other areas where metal-to-metal electrical contact is required.
Electrical requirements should therefore be considered at the same time as corrosion protection and cosmetic requirements.
Plan the Hardware Installation Sequence
The type of sheet metal hardware used in the part can affect the finishing sequence.
Some hardware may be installed before finishing, while other components should be installed afterward because of cure temperature, masking, electrical contact, cosmetic, or assembly requirements.
Temperature-sensitive plastics, adhesives, seals, inserts, or other components should be evaluated before they are exposed to a powder-coat cure cycle.
If a specific hardware surface must remain conductive or free of coating, identify that requirement on the drawing.
Provide a Way to Hold or Hang the Part
Parts need to be supported, hung, or fixtured while coating is applied and cured or dried.
When cosmetic requirements are strict, consider where the part can be held without creating an unacceptable visible contact point.
Existing holes or non-cosmetic features may provide suitable locations. If the design does not provide an appropriate location, discuss the finishing requirements with your fabricator before finalizing the part.
Consider Drainage and Enclosed Geometry
Surface preparation and pretreatment processes may expose the part to cleaning or treatment solutions before the final coating is applied.
Closed sections, blind cavities, overlapping seams, or other geometry that traps liquid can create finishing challenges.
Where appropriate, design parts so process liquids can drain and surfaces can be properly prepared and coated.
Pretreatment Matters for Corrosion Resistance
When corrosion resistance is important, the final coating should not be evaluated by itself.
Surface preparation and pretreatment can have a major impact on coating adhesion and corrosion performance. The appropriate pretreatment depends on the substrate, coating system, environmental exposure, and customer specification.
A powder-coated part with one pretreatment system should not automatically be assumed to provide the same corrosion performance as another powder-coated part using a different system.
If your product has a specific corrosion-resistance requirement, communicate the environmental and coating requirements during the RFQ process.
When Should You Choose Powder Coating?
Powder coating is often a strong option when:
- A durable cosmetic finish is required
- The part is a fabricated steel or aluminum enclosure, bracket, panel, cover, or similar component
- A wide selection of colors, gloss levels, or textures is desired
- The part can tolerate the required cure temperature
- The coating thickness is compatible with the assembly requirements
- The project does not require a specific wet-paint system
- In-house powder coating at ASM provides a manufacturing or lead-time advantage
When Should You Choose Wet Paint?
Wet paint may be the better option when:
- The drawing or customer specification requires a particular paint system
- A specialized coating chemistry is required
- The product has complex multi-color requirements
- A legacy or existing finish needs to be matched
- The assembly contains components that cannot tolerate powder-coat curing temperatures
- Touch-up or field repair is an important consideration
- The specified coating system is better suited to the service environment
The best choice ultimately depends on the complete part and application rather than simply comparing powder coat and wet paint in isolation.
What to Include on Your Drawing or RFQ
When requesting a finished custom sheet metal part, provide as much of the finishing requirement as possible.
Depending on the project, include:
- Finish type: Powder coat, wet paint, or customer specification
- Color: RAL, manufacturer color, customer color, or approved sample
- Gloss: Required gloss level or range
- Texture: Smooth, textured, wrinkle, or other requirement
- Coating specification: Manufacturer, product number, military specification, or customer specification if applicable
- Masking: Surfaces, holes, threads, or features that must remain uncoated
- Cosmetic surfaces: Identify surfaces with specific appearance requirements
- Grounding: Identify electrical contact or bonding surfaces
- Critical fits: Identify dimensions or interfaces affected by coating buildup
- Environmental requirements: Indoor, outdoor, corrosion exposure, chemicals, or other relevant conditions
The more clearly these requirements are defined, the easier it is for the fabricator and finisher to quote and manufacture the finished part correctly.
Powder Coating and Wet Paint for Custom Sheet Metal Parts
Approved Sheet Metal offers sheet metal finishing services as part of complete custom fabrication projects.
We provide powder coating in-house and can coordinate wet paint requirements through outside finishing partners.
When submitting your RFQ, include the 3D model, 2D fabrication drawing, coating specification, color, masking requirements, cosmetic requirements, and any critical assembly or environmental considerations.
That allows our team to evaluate the finish as part of the complete manufacturing process rather than treating it as an afterthought.
Request a quote for your next custom sheet metal fabrication project.
6 Tips for Designing Powder Coated Sheet Metal Parts
POWDER COATING
With over two decades of experience in powder coating, we’ve learned that a little bit of foresight yields superior outcomes. Here are our top tips for powder coated sheet metal parts.
Read the 6 TipsSheet Metal Fabrication Powder Coat or Wet Paint FAQ
What is the primary difference between powder coating and wet paint in sheet metal finishing?
Powder coating involves electrostatically spraying thermoplastic powder onto the part, which is then cured in an oven. Wet paint, on the other hand, involves applying liquid paint with a spray gun after applying a primer.
How do I ensure the correct color and gloss level when opting for powder coating?
When requesting powder coating, providing the exact RAL code for your preferred color and gloss type is crucial. This detailed code ensures precision in color selection, especially considering the wide variability among seemingly similar shades.
What are the advantages of powder coating over wet paint?
Powder coating is typically faster and more cost-effective as it requires less curing time compared to wet paint, which demands drying time for both primer and paint applications. It’s versatile and provides excellent protection for various applications and environmental conditions.
When might wet paint be a more suitable choice over powder coating?
Wet paint is preferable for multi-color parts without the risk of adhesive residue. However, it generally takes more time and can be costlier due to the multiple application steps. When time or budget constraints exist, powder coating often becomes the better option.
How does Approved Sheet Metal assist in selecting the ideal finishing method for custom sheet metal parts?
At ASM, we’re dedicated to helping you achieve the perfect finish for your parts. Whether it’s powder coating within our facilities or outsourcing wet paint services, we guide you through the selection process to ensure exceptional results aligning with your specific needs.