Disclosed is water based ink having metallic luster adapted for a direct-filling ball-point pen, which is used by being directly filled into the tube, said ink comprising, based on the total amount of the ink composition, 1% to 20% by weight of a metallic color pigment comprising metallic powder and a color pigment adsorbed thereon, 0.1% to 1.0% by weight of a water-soluble or water-dispersible polymer agent which imparts pseudo-plasticity, and water, thereby providing ink satisfactory in beauty and luster and excellent in aging stability and writing properties.

Provided is a water based ink having a metallic lustrous color for a ballpoint pen in which a metal powder pigment or aluminum powder and a complementary colorant (pigment or a colored water-insoluble polymer fine particles) are used as a colorant and further in addition to a thickener, a polar solvent and water, particularly a resin emulsion is used in combination to reduce the use amount of the thickener to thereby lower the viscosity. The ink is improved in follow-up property to be able to write continuously, develops a metallic color of a rainbow color on writing paper having a dark color and provides lines having water resistance and weatherability. The ink does not allow the metal powder and the pigment to settle and separate though the viscosity is low.

In order to provide a color metallic pigment capable of implementing diverse colors, excellent in finished appearance and weather resistance and manufacturable by a safe and simple manufacturing method, a color metallic pigment comprising metal particles and a single-layer or multilayer coat covering the surface of each metal particle characterized in that at least one layer of the single-layer or multilayer coat is a cobalt coat consisting of an anhydrous oxide film elementally containing cobalt is provided. This cobalt coat preferably contains a compound in composition expressed by at least one type of composition selected from a group consisting of CoO, Co.sub.2O.sub.3, Co.sub.3O.sub.4, nCoO.mAl.sub.2O.sub.3 and nCoO.mSiO.sub.2 (n, m: arbitrary positive real numbers).

A method of protecting a surface has the steps of providing a coating material containing sufficient aluminum flakes to provide a physical barrier to corrosion; and applying the coating material to a surface, thereby protecting the surface with an armor of aluminum. The method provides a coating material comprising about 3% to about 25% by weight of aluminum flakes, about 5% to about 20% by weight of aluminum flakes and about 7% to about 15% by weight of aluminum flakes. The aluminum flakes in the coating material can be non-leafing. A method of treating old concrete and rusting rebar, calls for providing a coating material containing sufficient aluminum flakes to provide a physical barrier to corrosion and polyisocyanates with sufficient unreacted NCO groups to scavenge water and provide a water-tight coating; and applying the coating material to the surfaces of damaged concrete and exposed rebar, thereby protecting the surfaces with an armor of aluminum. A method of restoring bridges whose zinc chromate paint needs to be repaired calls for providing a coating material containing sufficient aluminum flakes to provide a physical barrier to corrosion and polyisocyanates with sufficient unreacted NCO groups to scavenge water and provide a water-tight coating; and applying the coating material to the zinc chromate surface.

A method of protecting surfaces from corrosion calls for providing a coating material containing polyisocyanates with unreacted, active NCO groups; and applying the coating material to a rust covered surface, whereby the free NCO groups in the coating material react with the moisture in the rust to dehydrate the rust and produce a strong coating which keeps out water and oxygen which corrode surfaces. The active NCO content is about 3% to about 20% NCO groups. Also disclosed is a composition for coating an iron surface, the composition comprising polyisocyanates whose NCO content is between 5% and 30%; and aluminum flakes at about 5% to about 50% by weight.