Chemicals Required

  • De-ionized or distilled water (DI) . (One can just use the water collected from say a domestic tumble drier).
  • Potassium ferricyanide (available from or in USA and Canada from )
  • Thionin dye, the chloride salt is the most preferable and was until recent years the standard form of  it. But the acetate salt is now the only form commonly available (eg. from ) .  [A special offer of thionin is available for a limited period in the USA and Canada from ]
  • Ferrous sulphate (sulfate).  Available in USA and Canada from
  • Sodium bisulphate (sodium hydrogen sulphate). N.B. Not “bisulphite”.
  • EDTA  (ethylenediaminetetraacetic acid, the free acid powder) . [N.B. This MUST be the free acid powder and not a sodium salt]. (Available from ). For USA, or Canada,
  • Sodium sulphite (sulfite) anhydrous. Na2SO3. Available in USA and Canada from

DEA, Diethanolamine. (Available from ). Alternatively TRIS Base can be used. This is a convenient solid crystalline alternative which gives the same result as  DEA but needs about double the exposure time. Available from :

All chemicals and equipment are readily available at low cost from Internet suppliers. Without exception the chemicals advocated are not acutely toxic, nevertheless safety precautions should always be taken to keep chemicals away from children.

Blyth, J. & Richardson, M. De Montfort University, The Gateway, Leicester, LE1 9BH

Non-holographic imaging systems