The National Archives made a blue ink using a phthalocyanine pigment, which was ground into a very high molecular weight alcohol, then diluted with a much lower molecular weight one, and finally some water. We had the pigment in dry form, however when we looked into the repurchase, it was only available dissolved in water, which emphasizes the point that the pigment had to be ground into a very insoluble alcohol to protect it from water solubility.-Su (who used to do this)
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