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.

A leuco composition comprises at least one reactive leuco compound, which reactive leuco compound comprises a leuco moiety and at least one reactive moiety covalently bound to the leuco moiety. A laundry care composition comprises a laundry care ingredient and a leuco composition. A method of treating a textile comprises the steps of (i) treating a textile with an aqueous solution containing a leuco composition, (ii) optionally, rinsing the textile, and (iii) drying the textile.

A leuco composition comprises at least one reactive leuco compound, which reactive leuco compound comprises a leuco moiety and at least one reactive moiety covalently bound to the leuco moiety. A laundry care composition comprises a laundry care ingredient and a leuco composition. A method of treating a textile comprises the steps of (i) treating a textile with an aqueous solution containing a leuco composition, (ii) optionally, rinsing the textile, and (iii) drying the textile.

A leuco polymer includes a leuco monomer and an alkene. The leuco polymer has a molecular weight of at least 500 and is obtainable by polymerization of the leuco monomer and one or more alkene co-monomers. The leuco monomer consists of an alkene covalently bound to a leuco moiety and the leuco monomer has a molar extinction coefficient at a wavelength in the range 400 to 750nm of less than 1000 M.sup.1cm.sup.1. The alkene monomer(s) have a molar extinction coefficient at a wavelength in the range 400 to 750nm that is less than 100 M.sup.1cm.sup.1. Methods of making the leuco polymer, laundry care compositions comprising the leuco polymer and methods of treating textiles with such laundry care compositions.