When it comes to protecting aluminum parts from corrosion and preparing them for painting or electrical conductivity, chemical conversion coatings (often referred to as chem film or chromate conversion) are a reliable and widely used solution. But not all chem films are the same.

The two most common types, gold and clear chemical film coatings, offer different characteristics depending on your application needs. At The Bass Plating Company, we provide both finishes as part of our MIL-DTL-5541 compliant chemical film services, helping manufacturers and OEMs choose the right solution for function, finish, and cost.

What Are Chemical Film Coatings?

Chemical film coatings are chromate-based conversion coatings applied to aluminum surfaces. They are primarily used to:

• Protect against corrosion
  
• Maintain electrical conductivity
  
• Serve as a base for paint or adhesives

Unlike plating, chemical films do not add significant thickness to a part, making them ideal when dimensional tolerances are tight.

Gold vs. Clear Chem Film: What's the Difference?

The key difference between gold and clear chem film coatings comes down to appearance, corrosion resistance, and conductivity.

1. Color & Visual Appearance

Gold Chem Film

• Has a distinctive iridescent yellow/gold hue
• Offers a visual cue for quality control and coverage
• Preferred in aerospace and defense industries for traceability

Clear Chem Film

• Appears transparent or slightly bluish/silver
• Offers a clean, minimal look
• Ideal for applications where aesthetics matter (e.g., consumer electronics)

Bass Plating Insight: Some specs require color differentiation for QC verification, gold is easier to inspect visually.

2. Corrosion Protection

Gold Chem Film

• Offers superior corrosion resistance
• Meets stringent military and aerospace specs (Class 1A)
• Suitable for unpainted or outdoor applications

Clear Chem Film

• Provides moderate corrosion protection
• Best used when parts will be painted or used indoors
• Often specified for Class 3 applications requiring conductivity

Bottom line: If maximum corrosion resistance is required, go gold.

3. Electrical Conductivity

Clear Chem Film

• Designed to maintain low electrical resistance
  
• Common in electronic and electrical applications like grounding surfaces and connectors

Gold Chem Film

• Still conductive but with slightly higher resistance
• Used when balance between corrosion resistance and conductivity is needed

4. Spec Compliance & Environmental Considerations

Both gold and clear chem films can comply with MIL-DTL-5541, RoHS, and other industry standards, but formulas vary:

• Hexavalent chromium-based chem films offer higher protection but are being phased out in some industries.
• Trivalent chromium chem films (RoHS compliant) are more environmentally friendly and often appear clear.

At Bass Plating, we offer RoHS-compliant trivalent clear chem films and traditional hexavalent coatings to meet a wide range of customer and regulatory needs.

Why Choose Bass Plating for Chemical Film Services?

At The Bass Plating Company, we’ve been serving industrial and high-volume manufacturers since 1950. Our chemical film services are built for:

• Large-part processing
• High-volume production
• Precise rack finishing
• MIL-DTL-5541 Class 1A and Class 3 compliance

Whether you need corrosion protection, conductivity, or both, our team can help you select the right finish for your aluminum parts. Need guidance on whether gold or clear chemical film is right for your project? Let’s talk.

Frequently Asked Questions (FAQs)