Abstract: The present invention provides:(1) an ink composition erasable with a rubber eraser, the composition comprising 1 to 50% of a pigment, 3 to 50% of a resin having a film-forming temperature of 40.degree. C. or higher, 0.5 to 50% of an organic solvent and 7 to 60% of water, based on the weight of the ink composition;(2) an ink composition erasable with a rubber eraser, the composition comprising 2 to 90% of a pigment coated with a resin having a film-forming temperature of 40.degree. C. or higher, 0.5 to 30% of an organic solvent and 0.5 to 30% of water, based on the weight of the ink composition; and(3) an ink composition erasable with a rubber eraser, the composition comprising 2 to 90% of a pigment coated with a resin having a film-forming temperature of 40.degree. C. or higher, 1.5 to 55% of an emulsion (calculated as solids), 0.5 to 30% of an organic solvent and 4.0 to 60% of water, based on the weight of the ink composition.

Abstract: An ink composition for writing or marking on an absorbent or pervious writing surface to provide a writing or marking composed of an inner portion of a first color with outer contour portions therearound of a second color, which composition comprises:a first colorant,a second colorant anda vehicle,said first colorant being dispersed in said vehicle and having a particle size sufficiently large so as to substantially not permeate or be absorbed into said writing surface andsaid second colorant being dispersed or dissolved in said vehicle, being capable of substantially permeating or being absorbed into said writing surface and diffusing into the area on said surface proximate to said writing,whereby said second colorant forms said outer contour portions around said inner portion of said first colorant.

Abstract: An implement for writing on an absorbent or porous surface as provided, said implement including a writing or marking tip and said implement containing a writing medium, wherein said writing medium comprises an ink composition including:a first colorant,a second colorant anda vehicle,said first colorant being dispersed throughout said vehicle and having a particle size sufficiently large so as to substantially not permeate or be absorbed into said writing surface andsaid second colorant being dispersed or dissolved throughout said vehicle and being capable of substantially permeating or being absorbed into said writing surface and diffusing into the area on said surface proximate to said writing,whereby writing applied by said implement to said surface includes an inner portion of said first colorant bordered by substantial outer portions formed by said second colorant.

Abstract: A method for writing or marking on an absorbent or pervious writing surface to provide a writing or marking composed of an inner portion of a first color with outer contour portions therearound of a second color, which method comprises applying to said surface a writing or marking with an ink comprising:a first colorant,a second colorant anda vehicle,said first colorant being dispersed in said vehicle and having a particle size sufficiently large so as to substantially not permeate or be absorbed into said writing surface andsaid second colorant being dispersed or dissolved in said vehicle, being capable of substantially permeating or being absorbed into said writing surface and diffusing into the area on said surface proximate to said writing,whereby said second colorant forms said outer contour portions around said inner portion of said first colorant.

Abstract: A water base pigment ink composition for writing comprises a pigment, a dispersing agent, an anti-drying agent and an aqueous medium, in which said dispersing agent is a water soluble amine salt or ammonium salt of a copolymer comprises at least 50 molar % of a hydrophobic addition-polymerizable monomer and less than 50 molar % of acrylic acid or methacrylic acid, and said anti-drying agent is urea, thiourea or a derivative thereof.