SHANGHAI, May 2 (SMM) –SHFE 1709 tin opened at RMB 142,980/mt on Tuesday, jumping to RMB 145,790/mt before quickly falling back to RMB 144,100/mt. Finally, the most active contract ended up RMB 3,070/mt or 2.17% at RMB 144,660/mt. Trading volumes were down 4,138 lots to 10,510 lots, and positions were down 142 to 11,370. Commodity market rose across the board, with base metals up. However, SHFE tin may see its gains unsustainable and will face downward pressure.