Same Carbon Black Model, But Vastly Different Results? The Problem May Not Be the Carbon Black-Blog

In the application of carbon black, a common phenomenon often confuses customers and technicians alike:

"This carbon black doesn't give us enough jetness in our system, but it works great for others. Why?"

 "Is it a batch issue, or is your product unstable?"

 "It's the same model, but jetness, flow, and dispersion are all significantly different. How do you explain that?"

The key to these questions often lies not in the carbon black itself, but in its differing compatibility across various customer systems. This article explores the characteristics of carbon black in real-world applications to explain why such discrepancies arise and how to address them.

1. Why Does Carbon Black Performance Vary Across Systems?

Let’s start with a real-world example:

Customer A uses carbon black in a baking acrylic system and reports high jetness and gloss.

Customer B uses the same carbon black in a polyester-amino system, resulting in grayish tones and severe flooding.

Both customers use the same model and batch.

The fundamental reason is that carbon black performance heavily depends on the surrounding "system environment," including:

So, "no problem with the carbon black" ≠ "consistent performance across systems"—just like a person performs differently in different teams.

2. Four Key Compatibility Factors Between Carbon Black and Formulation Systems

1. Is the Wetting Stage Effective?

Carbon black has fine particle size and high surface energy. Only when fully wetted by the system can it enter the dispersion phase. If the resin or solvent polarity is mismatched, the carbon black may float and resist wetting.

2. Is the Dispersant Compatible?

Even "universal" dispersants may fail if polarity is mismatched, anchoring groups are weak, or dosage is insufficient. Results include:

l Poor initial dispersion

l Re-agglomeration after dispersion

l Caking and sedimentation during storage

High-surface-area or high-structure carbon blacks require adequate dispersant amounts and specific anchoring mechanisms (e.g., π–π interaction, ionic bonding).

3. Is the Resin Compatible Enough?

Some resins have bulky molecules or strong polarity, which can repel the carbon black or disrupt the dispersant layer, leading to flocculation or instability. Reactive resins (e.g., isocyanates) during baking may also cause pigment migration.

4. Is the Rheology of the System Reasonable?

Even with good dispersion, low-viscosity systems may allow particle settling, causing top-to-bottom color separation. Poor shear stability can lead to re-agglomeration or flooding.

3. Common Misconceptions: Mistaking System Issues for Carbon Black Problems

4. How to Identify Compatibility Issues vs. Product Quality Issues

Self-check protocol for customers:

1. Use the same dispersant to compare performance across different systems → observe system influence.

2. Use the same system to compare different carbon blacks → observe product differences.

3. Track the following changes:

a. Fineness change before/after storage

b.Jetness/gloss variation

c. Any floating/flooding observed in finger rub test

5. How Can Customers Resolve Compatibility Issues Themselves?

1. Establish a Compatibility Testing Routine:

l Does poor wetting cause wall adhesion?

l Does jetness rise quickly during dispersion?

l Is the fineness stable over time?

2. Optimize Related Formulation Variables:

l Type, dosage, and sequence of dispersant addition

l Adjust solvent polarity; add slower-evaporating components

l Fine-tune viscosity to balance shear and sedimentation

l Match pigment particle characteristics for compatibility

3. Create an Internal Carbon Black Evaluation Table:

Track and document performance of various carbon blacks in your formulations to build a reference database for future selection.

4. Sample Retention and Aging Tests:

l Natural aging for 3–7 days to monitor fineness and jetness changes

l Simulate stress conditions: heat storage, centrifugation, etc.

5. Long-Term Strategy:

l Develop a "recommended carbon black list" for each product line

l Archive each test result to avoid repeating errors

l Build a logical evaluation framework for internal training and customer communication

6. Conclusion

Carbon black is a highly system-dependent pigment. Even the same model can perform vastly differently in various formulations, dispersants, and application processes. Rather than blaming the carbon black, look within your system for the true mismatch.

By mastering these diagnostic methods, customers can avoid costly trial-and-error, improve consistency, and develop more robust formulations.

As a carbon black supplier, we’re committed to offering technical support and data to help you use carbon black more accurately, more stably, and more efficiently.