19 food red 7 basic yellow 28 acid yellow 9 acid blue 93 2 basic blue 9 basic green 1 basic violet 10 acid orange 8 basic red 14 basic red 49 basic green 4 and mixtures thereof a possible non reducible ink formulation comprises for example 8 10 sodium sulphite 15 triethanolamine tea and non reducible coloring agents comprising 3 0 direct blue 86 or 2 0 solvent green 7 or 0 6 acid red 52 or 2 0 acid blue 1 percentages by weight or mixtures thereof also the invention does not depend particularly on non reducible coloring agents generally any stable or solid coloring agent in the same formulation along with the reducing agent and complying with the conditions of the invention for non reducible coloring agents may be used preferably coloring substances recorded in the c i such as direct blue 86 solvent green 7 acid red 52 and acid blue 1 and mixtures thereof the reducing agent common to multiple color inks is sodium sulphite used in the formulation called 34 eraser 34 or 34 magic line 34 sylvapen although other reducing agents such as bisulphites thiosulphites are also useful in the instant invention sodium sulphite and alkaline metal hydrosulphites are preferred including organic reducing agents such as hydroquinone and formaldehyde sodium.