Technically Specified Natural Rubber (TSNR)

TSNR is graded on measurable laboratory parameters — dirt content, ash, nitrogen, volatile matter, and plasticity retention index — rather than visual appearance. This consistency makes TSNR more predictable in high-volume compounding operations, particularly for tire manufacturing, where batch-to-batch uniformity is critical. Smoked sheets, by contrast, are graded visually and can show more variability in processing characteristics.

Purchase contracts should reference the applicable national standard (e.g., SMR 20 or SIR 20) and specify maximum allowable values for each technical parameter — dirt content, ash, nitrogen, volatile matter, and PRI — along with the testing method (typically ISO or ASTM). Requiring a pre-shipment inspection certificate from an accredited laboratory provides an additional layer of quality assurance before the goods are loaded.