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.

Provided is an aqueous ink composition for a writing instrument which is excellent in a drying property of the drawn lines and a low temperature stability of the ink while inhibiting the pen tip from drying and which prevents the drawn lines from causing feathering and strike-through.

The aqueous ink composition for a writing instrument described above contains at least a colorant, trimethylglycine, pentaerythritol, 10% by mass or less of a water-soluble organic solvent, and water.

Provided is an aqueous ink composition for a writing instrument which is excellent in a drying property of the drawn lines and a low temperature stability of the ink while inhibiting the pen tip from drying and which prevents the drawn lines from causing feathering and strike-through.

The aqueous ink composition for a writing instrument described above contains at least a colorant, trimethylglycine, pentaerythritol, 10% by mass or less of a water-soluble organic solvent, and water.

An aqueous ink composition for a writing instrument may form a uniform coating film with low glossiness and is excellent in scratch resistance and water-resistant adherence even when writing is performed on a non-absorbing surface, and a writing instrument. Such an aqueous ink composition may include at least a coloring material, a neutralized product of an isobutylene-maleic anhydride copolymer, a polyol having two or more OH groups, a water-soluble resin and/or a resin emulsion, and water.

An aqueous ink composition for a writing instrument may form a uniform coating film with low glossiness and is excellent in scratch resistance and water-resistant adherence even when writing is performed on a non-absorbing surface, and a writing instrument. Such an aqueous ink composition may include at least a coloring material, a neutralized product of an isobutylene-maleic anhydride copolymer, a polyol having two or more OH groups, a water-soluble resin and/or a resin emulsion, and water.

To provide a marking ink composition for a writing board having excellent erasability of drawn lines, the marking ink composition essentially containing a pigment, a pigment dispersant resin, a masking agent, and a modified polyvinylalcohol or a polyvinylalcohol having a degree of saponification from 40 to 84% by molar ratio.

Disclosed is a coating composition suitable for coating onto a wall or other substrate to yield a dry-erase coating, The composition may be prepared by reacting an excess amount of an aminosilane with a carbonate in aqueous media to yield a silylurethane, introducing an epoxysilane, and allowing the epoxysilane to react with the aminosilane to yield an aminodisilane. This reaction will result in a coating composition that comprises the silylurethane and the aminodisilane. The aqueous mixture of the silylurethane and the aminodisilane together constitute a coating composition that, upon curing, forms a dry-erase coating.

Disclosed is a coating composition suitable for coating onto a wall or other substrate to yield a dry-erase coating, The composition may be prepared by reacting an excess amount of an aminosilane with a carbonate in aqueous media to yield a silylurethane, introducing an epoxysilane, and allowing the epoxysilane to react with the aminosilane to yield an aminodisilane. This reaction will result in a coating composition that comprises the silylurethane and the aminodisilane. The aqueous mixture of the silylurethane and the aminodisilane together constitute a coating composition that, upon curing, forms a dry-erase coating.

The disclosure provides transitorially erasable ink compositions, including an aliphatic hydrocarbon solvent, a rubber dissolved in the aliphatic hydrocarbon solvent, a hydrophilic pigment, and a surfactant. The disclosure further provides methods of preparing transitorially erasable ink compositions and writing instruments comprising transitorially erasable ink compositions. The disclosed erasable ink compositions write well, have strong color and erase easily transitorially, and demonstrate color stability.

The disclosure provides transitorially erasable ink compositions, including an aliphatic hydrocarbon solvent, a rubber dissolved in the aliphatic hydrocarbon solvent, a hydrophilic pigment, and a surfactant. The disclosure further provides methods of preparing transitorially erasable ink compositions and writing instruments comprising transitorially erasable ink compositions. The disclosed erasable ink compositions write well, have strong color and erase easily transitorially, and demonstrate color stability.