How to Make Blueprint Paper

Blueprint paper is a specially-coated paper that turns blue where it is exposed to light, while areas kept in the dark remain white. Blueprints were one of the first ways to make copies of plans or drawings. Here's how to make blueprint paper yourself.

Blueprint Paper Materials

• 15 mL of 10% potassium hexacyanoferrate(III) (potassium ferricyanide)
• 15 mL of 10% iron(III) ammonium citrate solution
• Petri dish
• Whitepaper
• Tongs or small paintbrush
• Small opaque object (e.g., coin, leaf, key)

Make Blueprint Paper

1. In a very dim room or in the dark: pour the potassium ferricyanide and iron(III) ammonium citrate solutions together into a petri dish. Stir the solution to mix it.
2. Use tongs to drag a sheet of paper across the top of the mixture or else paint the solution onto the paper using a paintbrush.
3. Allow the sheet of blueprint paper to dry, coated side up, in the dark. To keep the paper from being exposed to light and to keep it flat as it dries, it may help to set the wet sheet of paper on a larger piece of cardboard and cover it with another piece of cardboard.
4. When you are ready to capture the image, uncover the top of the paper and overlay an ink drawing on clear plastic or tracing paper or else simply set an opaque object on the blueprint paper, such as a coin or key.
5. Now expose the blueprint paper to direct sunlight. Remember: for this to work the paper must have remained in the dark until this point! If it's windy you may need to weigh down the paper to keep the object in place.
6. Allow the paper to develop in the sunlight for about 20 minutes, then cover the paper and return to the darkened room.
7. Thoroughly rinse the blueprint paper under cold running water. It's fine to have the lights on. If you do not rinse away any unreacted chemicals, the paper will darken over time and ruin the image. However, if all the excess chemicals are rinsed away, you'll be left with a permanent colorfast image of your object or design.
8. Allow the paper to dry.

Cleanup and Safety

The materials for making a blueprint (cyanotype) paper are safe to work with, but it's a good idea to wear gloves since you'll be working in the dark and might otherwise cyanotype your hands (turn them temporarily blue). Also, don't drink the chemicals. They are not particularly toxic, but they are not food. Wash your hands when you are done with this project.