Provided is aqueous ink composition for a writing instrument, which contains water and microspheres having a water-insoluble dye and a matrix constituted from a polymer wherein the water-insoluble dye is higher densely present in the inner part of the matrix than at the surface of the matrix, and at least one of the following (a) and (b) is satisfied: (a) the circularity coefficient of the microspheres, as measured by image analysis, is 0.6-1.0, and (b) the 10% strength of the microspheres, as determined in a micro-compression test, is 5-30 MPa.

A bearing assembly includes at least one inner ring and at least one outer ring, and at least one surface of the inner or outer ring is partially colored with an acid-free ink. If the at least one surface includes a surface defect such as a scratch in a black-oxide coating, the acid-free ink may be applied to the scratch to at least partially conceal it.

A bearing assembly includes at least one inner ring and at least one outer ring, and at least one surface of the inner or outer ring is partially colored with an acid-free ink. If the at least one surface includes a surface defect such as a scratch in a black-oxide coating, the acid-free ink may be applied to the scratch to at least partially conceal it.

High opacity permanent ink formulations comprising a solvent, a polymer-based opacifier, a coloring agent, a resin, and a humectant, wherein the ink formulation displays a viscosity of less than about 50 cP, are provided herein.

High opacity permanent ink formulations comprising a solvent, a polymer-based opacifier, a coloring agent, a resin, and a humectant, wherein the ink formulation displays a viscosity of less than about 50 cP, are provided herein.

Ink formulations and associated writing instruments are disclosed herein. In some embodiments, an ink formulation is provided which includes an ink resin or polymer and a biobased solvent. In some embodiments, an ink formulation is provided which includes an ink resin or polymer and a solvent comprising at least one lactate ester.

Ink formulations and associated writing instruments are disclosed herein. In some embodiments, an ink formulation is provided which includes an ink resin or polymer and a biobased solvent. In some embodiments, an ink formulation is provided which includes an ink resin or polymer and a solvent comprising at least one lactate ester.

The disclosure relates to a solvent-free photocrosslinkable writing ink advantageously for a pen, including, as a percentage by weight relative to the total weight of the ink: abetween 40 and 75% of a photocrosslinkable acrylate and/or methacrylate oligomer, bbetween 1 and 55%, optionally, of a photocrosslinkable acrylate and/or methacrylate monomer, cbetween 0.5 and 6% of a photoinitiator, dbetween 1 and 10% of a dye, advantageously a basic dye, and ebetween 0 and 10% of an additive. The present disclosure further relates to a method for securing a writing medium using the ink, the crosslinked ink obtained by crosslinking the ink and a pen for photocrosslinkable ink including the ink.

The disclosure relates to a solvent-free photocrosslinkable writing ink advantageously for a pen, including, as a percentage by weight relative to the total weight of the ink: abetween 40 and 75% of a photocrosslinkable acrylate and/or methacrylate oligomer, bbetween 1 and 55%, optionally, of a photocrosslinkable acrylate and/or methacrylate monomer, cbetween 0.5 and 6% of a photoinitiator, dbetween 1 and 10% of a dye, advantageously a basic dye, and ebetween 0 and 10% of an additive. The present disclosure further relates to a method for securing a writing medium using the ink, the crosslinked ink obtained by crosslinking the ink and a pen for photocrosslinkable ink including the ink.

An ink and method of conducting an examination suitable for reducing the likelihood that the students' answers on paper-based examinations may be changed at a later time prior to being graded. The ink includes a solution of marking particles, a suspension material, and a preserving material. A mark made with the ink is initially erasable for a predetermined period of time after the mark is formed and after the expiration of the predetermined period of time the mark is not erasable. The method of conducting an examination includes providing an ink to an individual, and then providing questions to an individual wherein the individual indicates answers to the questions by producing marks with the ink.