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Aug 19, 2026

ASTM D789: The hidden challenges behind reliable polyamide viscosity testing

Relative viscosity is a key quality parameter in polyamide production – but obtaining reproducible ASTM D789 results is often more challenging than expected. Sample preparation, cleaning procedures, solvent handling and system design can all influence measurement reliability. This technical guide highlights the most common pitfalls in routine QC testing and explains which practical measures help improve safety, reproducibility and uptime.

ASTM D789 is widely used for determining the relative viscosity of polyamides. While the calculation itself is straightforward, laboratories frequently face challenges that can affect result consistency. Differences in sample preparation, residue build-up from concentrated polymer solutions and the safe handling of 90% formic acid are among the most common sources of variability.

The technical guide compares ASTM D789 with ISO 307, discusses typical laboratory challenges and demonstrates how system design can contribute to safer operation, more reproducible measurements and reduced downtime. Readers will also learn why cleaning strategies and chemically resistant components play a critical role in long-term ASTM D789 performance.

👉 Download the technical guide and discover practical recommendations for reliable ASTM D789 testing of polyamides:
ASTM D789 Technical Guide