
A liquid ink composition having a sodium ion concentration between about 0.001 and 0.2% by weight or ink tank formed of resin or synthetic rubber containing between about 10 and 100 ppm of fatty acid or fatty acid derivatives is provided. The liquid composition is useful in every ink tank formed of resin or synthetic rubber containing fatty acid or the derivatives. The ink tank is also useful in despite of sodium ion concentration of ink. Formation of insoluble substances produced to react with ...











