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.

The present invention provides an epidermal penetration type ink composition comprising: a fluorescent colorant containing at least one selected from the group consisting of indocyanine green (ICG), cyanine, phthalocyanine, oxazine, rhodamine, and a mixture thereof; a binder resin containing at least one of polyvinylpyrrolidone (PVP) and polyvinylbutyral (PVB); and a solvent containing at least one of ethanol and isopropanol.

The present invention provides an epidermal penetration type ink composition comprising: a fluorescent colorant containing at least one selected from the group consisting of indocyanine green (ICG), cyanine, phthalocyanine, oxazine, rhodamine, and a mixture thereof; a binder resin containing at least one of polyvinylpyrrolidone (PVP) and polyvinylbutyral (PVB); and a solvent containing at least one of ethanol and isopropanol.

The present invention concerns a kit comprising a) an aqueous writing ink composition, containingmetal nanoparticles as coloring agent wherein said metal nanoparticles essentially consists of metal and said metal is chosen from silver, gold, aluminum and/or copper anda dispersing agent, and b) an eradicator fluid containing at least one oxidizing agent. It also concerns an aqueous eradicator fluid for erasing an aqueous writing ink composition containing metal nanoparticles as the coloring agent, in which said metal nanoparticles said fluid containingan oxidizing agent anda volatile solvent. It further concerns a writing instrument containing the eradicator fluid, the use of the eradicator fluid and/or of the kit containing it and a method of correcting errors of a written mark made on porous substrate.

The present invention concerns a kit comprising a) an aqueous writing ink composition, containingmetal nanoparticles as coloring agent wherein said metal nanoparticles essentially consists of metal and said metal is chosen from silver, gold, aluminum and/or copper anda dispersing agent, and b) an eradicator fluid containing at least one oxidizing agent. It also concerns an aqueous eradicator fluid for erasing an aqueous writing ink composition containing metal nanoparticles as the coloring agent, in which said metal nanoparticles said fluid containingan oxidizing agent anda volatile solvent. It further concerns a writing instrument containing the eradicator fluid, the use of the eradicator fluid and/or of the kit containing it and a method of correcting errors of a written mark made on porous substrate.

A kit comprising a) an aqueous writing ink composition, containingmetal nanoparticles as coloring agent wherein the metal nanoparticles essentially consists of metal and the metal is chosen from silver, gold, aluminum and/or copper anda dispersing agent, and b) an eradicator fluid containing at least one oxidizing agent. An aqueous eradicator fluid for erasing an aqueous writing ink composition containing metal nanoparticles as the coloring agent, in which the fluid contains an oxidizing agent anda volatile solvent. A writing instrument containing the eradicator fluid, the use of the eradicator fluid and/or of the kit containing it and a method of correcting errors of a written mark made on a porous substrate.

A kit comprising a) an aqueous writing ink composition, containingmetal nanoparticles as coloring agent wherein the metal nanoparticles essentially consists of metal and the metal is chosen from silver, gold, aluminum and/or copper anda dispersing agent, and b) an eradicator fluid containing at least one oxidizing agent. An aqueous eradicator fluid for erasing an aqueous writing ink composition containing metal nanoparticles as the coloring agent, in which the fluid contains an oxidizing agent anda volatile solvent. A writing instrument containing the eradicator fluid, the use of the eradicator fluid and/or of the kit containing it and a method of correcting errors of a written mark made on a porous substrate.

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.

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.