How to Select the Right Rubber Grade

By Bangkok Export Team · Bangkok, Thailand

Choosing between TSR block rubber, RSS and latex is one of the most common questions we receive from new buyers. The right answer depends on your production process, target quality and budget. Here is a practical framework.

Start with your application

• Tires, retreading, conveyor belts, molded technical parts → TSR block rubber, most commonly STR 20. It offers consistent technical properties at competitive cost.
• Light-colored or visible rubber components → STR 5L or RSS 1, where low dirt content and lighter color matter.
• Traditional tire construction, footwear, belts → RSS grades 1–5, selected by cleanliness and color requirements.
• Dipped goods, foam, rubber threads, adhesives → concentrated latex 60%, chosen as HA or LA depending on your process and odor requirements.

Understand the key parameters

Dirt content

The single most visible quality differentiator. STR20 typically allows up to 0.16%, while STR5L and RSS1 are around 0.05%. Lower dirt means cleaner processing and better finished-goods consistency — at higher cost.

Mooney viscosity & plasticity

Mooney viscosity indicates processability — too high and mixing is difficult, too low and the compound lacks strength. Always match your mixer's capability with the grade's typical range.

Volatile matter & ash

High volatile matter can cause porosity in vulcanized products; ash reflects mineral residue. Both are capped in export specifications and shown on the COA.

Always confirm with the COA

Specifications on paper mean little without per-shipment verification. Insist on a Certificate of Analysis for every lot, and keep reference samples from accepted shipments for comparison.

Quick decision table