Invisible Ink

Fulfilling many a childhood fantasy, Invisible Ink is for amateur spies and sleuths or just for those looking for a medium that's a little less permanent. Clear and invisible when applied to paper, the water-based ink turns blue when exposed to heat (like a light bulb) and disappears again when it cools. Packaged in an old-fashioned ink bottle, it also requires old-fashioned implements (a nib, glass or quill pen). It's $16 from The Library Shop.

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