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        # How Calcium-Zinc (Ca-Zn) Stabilizers Work in Lead-Free PVC Compounding

        

**Topic:** Explainer

        

As the Indian and global polymer sectors phase out lead stabilizers, Calcium-Zinc (Ca-Zn) one-pack systems have become the primary non-toxic alternative. Using [NBT Heat Stabilizers (Ca-Zn One-Pack)](/products/additives/heat-stabilizers) alongside [NBT ESBO](/products/additives/esbo) prevents the rapid thermal degradation known as zinc burn, ensuring compliance with RoHS and local environmental mandates.

        
        
        
        
        
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          ## Frequently Asked Questions

          
### Why does Ca-Zn require ESBO?

ESBO acts as a synergistic acid scavenger and ZnCl₂ complexing agent, preventing the Lewis acid from initiating the rapid degradation known as zinc burn.

### What is the optimal calcium-to-zinc ratio?

For rigid PVC (low processing temperature), a higher zinc ratio is used for color hold. For flexible PVC (high shear and heat), a higher calcium-to-zinc ratio is specified to maximize long-term stability.

### Can Ca-Zn replace lead stabilizers in pressure pipes?

Yes. Modern Ca-Zn packages are fully optimized to provide the fusion torque and mechanical properties required to meet IS 4985 rigid pipe specifications.

### Does Ca-Zn affect cable insulation resistivity?

With high-purity metal soaps and the addition of calcined clay, Ca-Zn stabilized compounds easily meet IS 694 cable volume resistivity requirements.

        
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By NBT Technical Desk · Updated 2026-07-04

        

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