Tung oil

Buyers should prioritize the refractive index (1.5165–1.5210 at 25°C) and iodine value (163–173 mg I2/g), as these are primary indicators of purity and drying capability. Ensure the oil is 100% pure cold-pressed, as heat-treated or solvent-extracted versions may have altered polymerization properties. For industrial applications, check the acid value (typically <5 mg KOH/g) to ensure it won't react negatively with metal containers or specific wood tannins.

Raw Tung Oil is best for deep penetration into wood fibers but has a long drying time (24-48 hours per coat) and a matte finish. Polymerized Tung Oil has been pre-heated to speed up the drying process and provides a glossier, harder surface. If your project requires food-safe certification (e.g., for cutting boards), verify that the supplier provides FDA-compliant documentation and that no metallic driers (like cobalt or manganese) have been added.

Ensure the product meets ASTM D12-88 (Standard Specification for Raw Tung Oil). For European markets, compliance with REACH regulations is mandatory. Since Tung Oil is a natural vegetable oil, a Phytosanitary Certificate may be required by customs in certain countries. Always request a Material Safety Data Sheet (MSDS) to confirm the flash point and handling safety protocols.

Adulteration with soybean or rapeseed oil is a common risk. Request a Gas Chromatography (GC) analysis report to confirm the fatty acid profile, specifically the Eleostearic acid content, which should be above 75%. A simple field test is the Worstall's Test (Heat Test): pure Tung Oil will turn into a hard, dry, non-sticky solid when heated to specific temperatures, whereas adulterated oil will remain soft or tacky.

Tung Oil is prone to oxidation and polymerization if exposed to air or light during transit. Ensure the supplier uses nitrogen-flushed packaging in UV-protected HDPE drums or epoxy-lined steel barrels. For bulk shipments, Flexitanks are cost-effective but require strict temperature monitoring to prevent the oil from thickening in cold climates or oxidizing in extreme heat.

Tung Oil prices are subject to seasonal harvest fluctuations (typically harvested in autumn). It is wise to sign long-term supply contracts during peak harvest to lock in prices. On Made-in-China.com, look for suppliers in Hunan or Guizhou provinces, which are the primary production hubs. Negotiate for a tiered pricing structure where the price drops by 5-10% for full container loads (FCL) compared to LCL shipments.

Always utilize Secured Trading Services on Made-in-China.com to ensure payment is only released upon proof of shipment. For large orders, mandate a pre-shipment inspection (PSI) by a third party like SGS or Intertek to verify the volume and purity. Ensure the Bill of Lading (B/L) description matches the technical grade specified in your Proforma Invoice to avoid customs classification issues.

Check the HS Code (typically 1515.90) for your specific country to determine import duties. Some regions offer preferential tariff rates for agricultural derivatives from China under specific trade agreements. Be aware that as a combustible liquid (though with a high flash point), some ports may classify it under Class 9 miscellaneous dangerous goods depending on the concentration and additives, affecting local drayage costs.