Tin Ingots for Solder, Bronze and Tinning

IS 26, the Indian Standard for tin ingot, was revised in 2024 and now lists six grades: Sn99.75, Sn99.85, Sn99.90, Sn99.93, Sn99.95 and Sn99.99. The number is the minimum tin content. Impurities controlled include antimony, arsenic, bismuth, cadmium, copper, iron, lead, aluminium and zinc.

Sn99.85 is the common trading grade and matches the LME minimum and the Grade A tin of ASTM B339. Electronics solder makers usually ask for higher purity, Sn99.9 or above, because lead, copper and other trace elements change wetting and joint reliability, and lead-free solders must stay below strict lead limits. For bronze and gunmetal foundry work, Sn99.85 is generally sufficient.

Traditional soft solder is a tin-lead alloy; 63/37 tin-lead melts sharply at 183 °C, the eutectic point, which is why it became the electronics standard. Lead-free solders such as tin-silver-copper alloys are now mostly tin, often over 95 percent, and melt a little higher at around 217 to 220 °C.

Solder makers melting their own alloy need clean tin and clean lead. Our tin-lead solder alloys page covers ready-made solder metal, and lead ingots are listed separately.

Bronze is copper hardened with tin. Tin raises strength, hardness and wear resistance and improves corrosion resistance in seawater. Phosphor bronze adds a small amount of phosphorus as a deoxidiser and is the classic bearing and spring material. Gunmetal is copper with tin and zinc, often with a little lead for machinability and pressure tightness, used for valves, pump parts and bushes.

Foundries making these alloys add tin as ingot to the copper melt. Our phosphor bronze and gun metal pages describe the finished alloys.

Hot tinning dips copper wire, strip or steel parts into molten tin to give a solderable, corrosion-resistant coating. Tinned copper conductors and busbars are a common example. Tin-based white metals, often called babbitt, combine tin with antimony and copper to line plain bearings in engines, compressors and turbines; workshops that reline bearings need tin of known purity so the finished alloy stays in specification.

Tin pest: below about 13 °C, ordinary white tin can slowly transform into grey tin, a brittle powdery form. In practice this needs prolonged cold and is slowed by small amounts of impurities such as antimony or bismuth, so it rarely troubles ingots stored in Bangalore. It is worth remembering for material shipped to or stored in cold climates.

Tin cry: bend a bar of pure tin and it makes a faint crackling sound as its crystals twin. It is a neat field check that you are holding fairly pure tin, although it is no substitute for analysis.

Tell us the grade, quantity and end use. Tin lots from Jubilant Impex can be supplied with a test certificate through a Government-recognised test house, showing tin content and impurities against the requested grade.

Because tin is expensive, check weight and certificate together when the material arrives. Count the bars, weigh the lot, and match the lot number on the bars to the report. If you are switching suppliers for solder production, run a small trial melt before committing a full batch; a slightly different impurity profile can change how the solder wets even when both lots meet the same grade.