Abstract: A leuco dye pastel marking device for use with a substrate treated with an activator of the leuco dye, such that drawing upon the substrate will reveal a color, but drawing on a normal surface will have no visible effect. A solvent such as dimethyl adipate is used to store the leuco dye in a longer-lived, more stable, solid form, and varying hardnesses and consistencies may be achieved by the addition of 12 hydroxystearic acid and ethyl cellulose. The substrate may be treated selectively with the activator such that a texture, image, or hidden message is revealed by the application of the leuco dye pastel to the substrate. One or more substrates and one or more leuco dye pastel marking devices may be presented to a child as a coloring book with pastels that only visibly mark the coloring book and no other surface.

Abstract: A leuco dye pastel marking device for use with a substrate treated with an activator of the leuco dye, such that drawing upon the substrate will reveal a color, but drawing on a normal surface will have no visible effect. A solvent such as dimethyl adipate is used to store the leuco dye in a longer-lived, more stable, solid form, and varying hardnesses and consistencies may be achieved by the addition of 12 hydroxystearic acid and ethyl cellulose. The substrate may be treated selectively with the activator such that a texture, image, or hidden message is revealed by the application of the leuco dye pastel to the substrate. One or more substrates and one or more leuco dye pastel marking devices may be presented to a child as a coloring book with pastels that only visibly mark the coloring book and no other surface.

Abstract: A leuco dye pastel marking device for use with a substrate treated with an activator of the leuco dye, such that drawing upon the substrate will reveal a color, but drawing on a normal surface will have no visible effect. A solvent such as dimethyl adipate is used to store the leuco dye in a longer-lived, more stable, solid form, and varying hardnesses and consistencies may be achieved by the addition of 12 hydroxystearic acid and ethyl cellulose. The substrate may be treated selectively with the activator such that a texture, image, or hidden message is revealed by the application of the leuco dye pastel to the substrate. One or more substrates and one or more leuco dye pastel marking devices may be presented to a child as a coloring book with pastels that only visibly mark the coloring book and no other surface.

Abstract: A leuco dye pastel marking device for use with a substrate treated with an activator of the leuco dye, such that drawing upon the substrate will reveal a color, but drawing on a normal surface will have no visible effect. A solvent such as dimethyl adipate is used to store the leuco dye in a longer-lived, more stable, solid form, and varying hardnesses and consistencies may be achieved by the addition of 12 hydroxystearic acid and ethyl cellulose. The substrate may be treated selectively with the activator such that a texture, image, or hidden message is revealed by the application of the leuco dye pastel to the substrate. One or more substrates and one or more leuco dye pastel marking devices may be presented to a child as a coloring book with pastels that only visibly mark the coloring book and no other surface.

Abstract: A color-changing marking system, including a color-changing marking medium and a substrate. The color-changing marking medium has a nominal color and includes a color developer activator and/or color former leuco dye. The substrate includes a treated portion on which a color former leuco dye and/or color developer activator has been applied. Application of the color-changing marking medium to an untreated portion of the substrate causes the color-changing marking medium to create marks of the nominal color. Application of the color-changing marking medium to the treated portion of the substrate causes the color-changing marking medium to create marks of a changed color in response to a chemical or mechanical reaction between the leuco dye and the activator. The marking medium may a crayon, colored pencil, marker ink or paint.

Abstract: A color-changing marking system, including a color-changing marking medium and a substrate. The color-changing marking medium has a nominal color and includes a color developer activator and/or color former leuco dye. The substrate includes a treated portion on which a color former leuco dye and/or color developer activator has been applied. Application of the color-changing marking medium to an untreated portion of the substrate causes the color-changing marking medium to create marks of the nominal color. Application of the color-changing marking medium to the treated portion of the substrate causes the color-changing marking medium to create marks of a changed color in response to a chemical or mechanical reaction between the leuco dye and the activator. The marking medium may a crayon, colored pencil, marker ink or paint.

Abstract: An invisible ink, a method for preparing an invisible ink, and an invisible ink product are disclosed herein. An invisible ink comprising a first ink combined with a second ink is applied to a print medium. The first ink comprises a color developer activator without a color former leuco dye and the second ink comprises a color former leuco dye without a color developer activator. The first ink is prepared with a polyvinyl alcohol binder, dispersant/surfactant, and a wetting agent. The second ink is prepared with a polyvinyl alcohol binder, grind aid, dispersant/surfactant and defoamer. Heat generated by rubbing and/or scratching the invisible ink on the print medium activates the color former leuco dye and activator to change the color on the printing medium.

Abstract: A method and compositions for authenticating a document or article comprises applying a mixture of a carrier, a leuco dye and an activator to a surface of a document or article, wherein the leuco dye and activator react in response to a rubbing force applied to the surface to change color and wherein the activator is at least one selected from the group consisting of amidophenol, anilides with hydroxyl groups and benzoamides with hydroxyl groups and authenticating the document or article by applying a rubbing force to the surface to effect a color change.