Color Selection Guide – From Color Difference Control to Weather Resistance Guarantee, How to Choose the Right Roller Coated Plate?

First , let's understand : What is color difference ΔE?

In the field of industrial coating, color difference is measured by ΔE (Delta E). The smaller the ΔE value, the closer the color is to the standard color swatch.

ΔE ≤ 0.5: Color difference is almost imperceptible to the naked eye.

ΔE 0.5-1.0: Distinguished by professional quality inspectors under specific lighting conditions.

ΔE 1.0-2.0: Slight color difference visible to the naked eye

ΔE > 2.0: Significant color difference

II. The color difference control capabilities of different processes vary greatly:

Roll coating : Continuous roll coating is used, with an entire batch of products completed within the same coating cycle, ensuring stable color difference control within ΔE ≤ 0.5. This is because key parameters such as paint mixing ratio, roll coating speed, and baking temperature remain consistent throughout the entire production process.

Spray painting : This is a piece-by-piece process, and each batch requires re-mixing the paint and resetting the spray gun parameters. Even when using the same can of paint, there will be slight differences in the spray thickness and baking time between different batches, resulting in a color difference ΔE that is usually between 1.0 and 2.0.

The same color and the same coating can produce vastly different results under different climatic conditions.

In regions with high UV radiation (Middle East, Southeast Asia, Africa): PVDF is the standard choice; polyester coating is not recommended for outdoor use .

Coastal areas with high salt spray: PVDF coating + 5052 alloy substrate, double protection .

Inland general climate: SMP or PE are both acceptable, depending on the project's positioning .

Third , the coating is not 'decoration,' but 'protection.'

How to judge coating quality? Three key indicators

Indicator 1: Fluorocarbon resin content

This is a core indicator for PVDF coatings, and the national standard requires it to be no less than 70%. Even if the coating appears to be 'fluorocarbon' based on the test report, its actual weather resistance is significantly worse. Request the supplier to provide a third-party test report, specifically checking the 'fluorocarbon resin content.'

Index 2: Coating Thickness.
The PVDF coating should be ≥20μm on one side and ≥25μm on both sides combined. Too thin, and the weather resistance will be insufficient; too thick, and the cost will be high and it will be prone to cracking. Measurement Method: Use a magnetic thickness gauge to measure at different points on the board surface.

Indicator 3: T-bend adhesion
. A bending test is performed on the sample; the coating should not crack or peel off at the bend. High-quality roller-coated sheets can achieve no paint peeling from 0T to 3T.

IV . A single table to understand: Matching schemes for different colors, coatings, and processes

VI. Practical Suggestions for Procurement

The following clauses must be clearly defined in the contract for the purchase of color coatings for roller-coated sheets:

1. Color difference standard
: 'Color difference ΔE ≤ 0.5 for products in the same batch, and color difference ΔE ≤ 1.0 between different batches'.

2. Standard color swatches
: 'The supplier shall provide two copies of the standard color swatches, which shall be signed and sealed by both parties and used as the basis for acceptance.'

3. Coating requirements:
'PVDF fluorocarbon coating, fluorocarbon resin content ≥70%, single-sided thickness ≥20μm. Supplier shall provide a third-party testing report.'

4. On-site samples
: 'Before mass production, the supplier shall provide no less than 5 on-site samples, which shall be installed on the project site and confirmed by the client before mass production can be arranged.'

VII. Conclusion:

For engineering procurement companies, color selection is not just an 'aesthetic decision,' but also a 'risk decision.'

Choosing the right color keeps costs under control; choosing the wrong color can lead to rework costs that are several times the cost of the materials themselves. Spending money on 'choosing the right color' is much more cost-effective than spending it on 'rework.'

DIXXIN has focused on engineering roller-coated plates for 25 years. What can we do for you?

Advantage 1: Roller coating process, color difference is controllable

DIXXIN has three fully automated roller coating production lines, which are monitored in real time by an online colorimeter. The color difference ΔE ≤ 0.5 within the same batch , and we can achieve zero color difference in the entire batch.

Advantage 2: Coating quality is verifiable.

DIXXIN roller-coated plates use PVDF fluorocarbon coating with a fluorocarbon content of ≥70%, and the test data for each batch is traceable.

Advantage 3: On-site sample support

Before mass production, DIXXIN can provide on-site samples for you to confirm the color effect during installation at the project site. Mass production will only be arranged after your satisfaction is confirmed – this step is not skipped.

If you are selecting roller-coated plate colors for your engineering project, please contact us for targeted selection advice and on-site sample support.