The Cyanotype sensitiser supplied as solution only or as part of the Cyanotype Kit is a single working solution and is an updated version of the original process. This formula uses Ammonium FerricOxalate to give a good blue which does not wash out and is twice as sensitive to UV as the traditional version. Development is in water. A citric acid solution can be used to manipulate contrast. All images are made by the contact system, where the image depends on a negative of the appropriate size or the placement of an object on the sensitised material.