Rising Rubber Prices Prompt Warning to Crumb Rubber Factories Over the Risk of Vulcanized Rubber Contamination in Raw Rubber Materials
Medan, August 28, 2026 – The recent increase in natural rubber prices has brought positive momentum for farmers and the rubber industry. However, amid this favorable trend, crumb rubber factories are being urged to remain vigilant against the potential circulation of Raw Rubber Materials (Bahan Olah Karet/BOKAR) contaminated with vulcanized rubber, which may be intentionally mixed in to obtain unlawful financial gains.
Such practices may become more attractive as vulcanized rubber is typically derived from scrap rubber products or waste materials with little or no commercial value. By mixing these materials into BOKAR, unscrupulous parties can artificially increase the weight of the product without improving the actual quality of the natural rubber.
Under Indonesian Minister of Agriculture Regulation No. 38/Permentan/OT.140/8/2008, BOKAR must be free from contaminants. This requirement is further reinforced by Minister of Trade Regulation No. 1 of 2026, which explicitly prohibits the presence of vulcanized rubber contaminants in BOKAR and Standard Indonesian Rubber (SIR).
More Than a Quality Issue—A Product Safety Concern
Vulcanized rubber contamination is not merely a quality issue. It may also affect the performance and safety of finished rubber products.
Technically, vulcanized rubber has already undergone a sulfur cross-linking process and therefore cannot blend homogeneously with raw natural rubber during rubber processing. As a result, vulcanized rubber particles may remain as foreign inclusions within the rubber compound.
These inclusions can create material inconsistencies, reduce mechanical performance, increase manufacturing rejects, and serve as initiation points for cracks during service. This concern is particularly significant for tires, where natural rubber is a critical raw material and structural integrity is directly related to road safety.
Maintaining the purity of BOKAR from the very beginning of the procurement process is therefore an essential part of quality assurance throughout the crumb rubber manufacturing chain.
Strengthen BOKAR Inspection Procedures
Crumb rubber factories and their procurement networks are encouraged to strengthen inspection and sorting procedures before accepting BOKAR as raw material.
The following aspects should receive particular attention:
Examine abnormal shapes and surface textures.
Look for unusual colors or suspicious internal layers.
Listen for distinctive sounds when the material is dropped, as vulcanized rubber often produces a different sound.
Cut or slice the material to inspect its internal structure and identify possible foreign inclusions.
Ensure that no foreign materials or non-natural rubber particles are present.
Any BOKAR suspected of containing vulcanized rubber or other contaminants should be rejected and excluded from the production process.
Companies are also encouraged to issue formal circulars or instructions to all suppliers, collectors, and purchasing agents prohibiting the purchase or sale of contaminated BOKAR to crumb rubber factories. Such preventive measures are essential to safeguard product quality and preserve the reputation of Indonesian natural rubber in international markets.
Recognizing the Difference
Inspection personnel should be trained to distinguish between natural rubber and vulcanized rubber.
In general, natural rubber exhibits a more homogeneous structure, is easier to cut, and does not contain embedded foreign materials. By contrast, vulcanized rubber is typically harder, more difficult to slice, may display different colors, and often retains characteristics of previously manufactured rubber products.
Whenever there is uncertainty, laboratory testing is recommended before the material is accepted for processing.
Criminal Sanctions May Apply
In addition to violating technical quality requirements, the intentional mixing of plantation products with foreign materials may have legal consequences.
Law No. 39 of 2014 on Plantations, as last amended by Law No. 6 of 2023, stipulates that the adulteration of plantation products with other materials, where the elements of Article 77 are satisfied, may be subject to criminal sanctions under Article 110, including imprisonment of up to five (5) years and fines of up to IDR 5 billion.
Accordingly, all stakeholders in Indonesia's rubber industry are encouraged to strengthen supply chain oversight and exercise greater vigilance during BOKAR procurement. Early detection and strict quality control are essential to maintaining the quality of Standard Indonesian Rubber (SIR), protecting downstream industries, and preserving global confidence in Indonesian natural rubber.