Galvalumed sheet

Galvalume Coil

Galvalume Roof

Introduction

If you have purchased Galvalume steel sheets, Aluzinc steel coils, or aluminum-zinc coated steel, you may have noticed that some products have a blue or green surface instead of the traditional silver-gray metallic appearance.

This raises an important question:
Why are Galvalume sheets coated blue or green? Is blue or green anti-fingerprint coating required by ASTM A792?

The answer is no. ASTM A792/A792M specifies the requirements for aluminum-zinc alloy-coated steel sheet, including the metallic coating, steel grade and other technical requirements. Blue or green anti-fingerprint coating is an additional surface treatment and is not a mandatory ASTM color requirement.

So why do suppliers offer blue and green AFP Galvalume?

The main reasons are fingerprint resistance, surface protection, appearance, handling performance and product differentiation.

1. What Is Anti-Fingerprint Coating on Galvalume?

Anti-fingerprint coating, often called AFP coating, is a thin protective surface treatment applied to Galvalume steel.
A simplified structure is:
Steel substrate → Aluminum-Zinc coating → Anti-Fingerprint coating
The Galvalume coating provides the primary metallic protection, while the AFP layer can improve the surface's resistance to:

• Fingerprints
• Oil marks
• Handling stains
• Moisture-related staining
• Surface contamination
• Minor storage damage

Some commercial Galvalume products use acrylic or other organic surface treatments to reduce fingerprinting and improve forming or handling performance.
This is why anti-fingerprint Galvalume steel is often preferred for applications where the surface will be handled frequently or remain exposed.

2. Why Is the AFP Coating Blue or Green?

The most important rule is:

Blue and green are not mandatory Galvalume colors.

Traditional Galvalume steel normally has a silver or metallic appearance.
Manufacturers can apply a colored AFP surface treatment to produce:

• Blue Galvalume
• Green Galvalume
• Gray Galvalume
• Golden Galvalume
• Other customized colors

The color is generally selected according to the buyer's application, appearance requirements or product identification needs.
Therefore:
Blue AFP does not automatically mean higher quality.
Green AFP does not automatically mean higher corrosion resistance.
The technical performance depends much more on the complete coating system, including the Galvalume coating weight, AFP formulation, coating thickness, adhesion and testing requirements.

3. Is Blue or Green AFP Required by ASTM A792?

No.
This is one of the most important points for Galvalume buyers.
ASTM A792/A792M covers aluminum-zinc alloy-coated steel sheet. Common commercial Galvalume coating designations include AZ50, AZ55, AZM150 and AZM180, depending on the applicable specification and market.
The ASTM requirement should therefore be considered separately from the AFP surface treatment.
For example, a purchase specification could be:
ASTM A792/A792M + G550 + AZM150 + Blue AFP
Here:

• ASTM A792/A792M = product standard
• G550 = mechanical grade
• AZM150 = Galvalume coating designation
• Blue AFP = additional surface treatment and color

This is much more precise than simply ordering:
Blue Galvalume Sheet

4. What Are the Benefits of Blue and Green AFP Galvalume?

1. Better fingerprint resistance

AFP treatment helps reduce visible fingerprints and handling marks during:

• Slitting
• Cutting
• Roll forming
• Transportation
• Installation

2. Improved surface protection

Depending on the formulation, AFP can provide additional protection against surface contamination, moisture and storage staining.

3. Better appearance

Blue or green surfaces provide a more consistent and distinctive appearance compared with untreated metallic Galvalume.

4. Improved processing

Some AFP coatings can provide lubrication during forming and roll-forming operations. Commercial Galvalume products with acrylic surface treatments are available specifically for applications where reduced fingerprinting and improved forming performance are required.

5. Blue AFP Galvalume vs. Green AFP Galvalume

Is one better?

Not necessarily.

The color itself does not determine the performance of the coating.

When comparing two suppliers, focus on the coating system and test results, not simply the color.

6. Is Anti-Fingerprint Galvalume the Same as PPGL?

No.
This distinction is important when sourcing steel from China.
Anti-Fingerprint Galvalume
Steel → Galvalume coating → AFP treatment
PPGL / Prepainted Galvalume
Steel → Galvalume coating → Pretreatment → Primer → Paint topcoat
PPGL is a prepainted steel product, while AFP Galvalume is primarily a surface-treated Galvalume product.
Therefore, a buyer searching for blue Galvalume sheet should confirm whether the supplier is offering:

• Blue AFP Galvalume
• Blue prepainted Galvalume / PPGL

They are not automatically the same product.

7. How Should Buyers Specify Blue or Green AFP Galvalume?

When purchasing blue or green anti-fingerprint Galvalume steel coil, specify the following:

Product

Galvalume steel coil / Aluzinc steel sheet

Standard

ASTM A792/A792M, EN, JIS or required standard

Grade

For example:

• G550
• Structural grade
• Commercial quality

Thickness & Width

For example:
0.50 mm × 1250 mm

Galvalume Coating

For example:
AZM150

Surface Treatment

Anti-Fingerprint / AFP

AFP Color

Blue / Green

Surface Finish

Specify:

• Regular spangle
• Minimized spangle
• Smooth surface

Inspection

Depending on the application:

• Coating weight
• Thickness
• Mechanical properties
• Surface quality
• Adhesion
• Forming performance
• Corrosion/humidity testing

A complete specification might look like:
ASTM A792/A792M, G550, AZM150, 0.50 × 1250 mm, Blue Anti-Fingerprint Galvalume Steel Coil, suitable for roll forming.
This gives the supplier a clear technical target.

8. Blue/Green AFP Galvalume: Key Buying Rules

Before placing an order, remember these five rules:

Rule 1 — Do not treat color as a quality grade.

Blue and green are surface colors, not mechanical grades.

Rule 2 — Check the Galvalume coating weight.

AZM150, AZM180 and other coating designations should be clearly specified.

Rule 3 — Confirm the AFP treatment.

Ask whether the product is actually anti-fingerprint coated.

Rule 4 — Do not confuse AFP Galvalume with PPGL.

A colored AFP coating is not automatically a conventional paint coating.

Rule 5 — Ask for technical documentation.

For larger projects, request an MTC and relevant coating or surface-treatment test results.

FAQ

1.Is blue Galvalume required by ASTM A792?

No. Blue is not a mandatory ASTM A792 color requirement.

2.Is green Galvalume required by ASTM?

No. Green AFP is an optional surface treatment/color specification.

3.What does AFP mean in steel?

AFP means Anti-Fingerprint. It refers to a surface treatment designed to reduce fingerprints and improve surface protection and handling performance.

4.Is blue AFP better than green AFP?

Not necessarily. The performance depends on the coating formulation and technical specifications rather than the color.

5.Is AFP Galvalume the same as PPGL?

No. AFP Galvalume uses a surface treatment, while PPGL uses a paint coating system.

6.Can blue or green AFP Galvalume be used for roofing?

Yes, depending on the steel grade, Galvalume coating, AFP system, forming requirements and environmental conditions.

Conclusion

Blue and green anti-fingerprint coatings on Galvalume sheets are not mandatory requirements under ASTM A792/A792M.
They are additional surface treatments used to improve fingerprint resistance, surface protection, appearance and handling performance.
For buyers sourcing blue AFP Galvalume, green AFP Galvalume, Aluzinc steel sheets, Galvalume steel coils or AZM150 Galvalume, the most important factors are not simply the color.
Instead, check:
Steel grade + ASTM standard + Galvalume coating weight + AFP treatment + AFP color + surface quality + application requirements.
A professional specification such as ASTM A792/A792M + G550 + AZM150 + Blue AFP is far more reliable than simply asking for “blue Galvalume sheet.”