Neutral pen according to colloidal chemical theory, colloidal in the of metal ion, especially high metal ion, has high of potential, attract around with instead charge of ion, formed double electric layer, damage colloidal solution of stability, as sewage processing in the, common high metal ion for flocculation gel agent as, can damage colloidal solution of stability, high ion, and variable price ion, as Al3+, and Ca2+, and Fe3+, and Fe2+, and Mn6+,Cr6+, on colloidal solution of stability has strong of damage role. Ink of metal ions introduced in reason: as a raw material for manufacture of ink, usually have to undergo a rigorous selection, and strictly prevent the introduction of metal ions, but due to various reasons, there is still a certain amount of metal ions are introduced. Some of these metal ions is part of the raw material compounds, not in a free State, but in combined state, the effect of some metal ions on colloidal stability is very small. Another part of the free metal ion impurities, which are manufacturing raw materials, adding excess metal ions, and made after the raw materials, not clean and residue, such as K1+,, Na1+,, Cr6+, and Fe3+,, Cu2+,, Ni2+, also has brought people of metal ion impurities in the raw materials, as well as water and reagents to the metal ion. The stability of free metal ions can damage the ink, the ink layer, precipitation, discoloration. Ink dye and pigment are a major source of metal ions into the.