Copper print

Make a print using copper sulfate and ascorbic acid!

10 minutes
Copper print



  • Put on protective gloves and eyewear.
  • Conduct the experiment on the plastic tray.
General safety rules
  • Do not allow chemicals to come into contact with the eyes or mouth.
  • Keep young children, animals and those not wearing eye protection away from the experimental area.
  • Store this experimental set out of reach of children under 12 years of age.
  • Clean all equipment after use.
  • Make sure that all containers are fully closed and properly stored after use.
  • Ensure that all empty containers are disposed of properly.
  • Do not use any equipment which has not been supplied with the set or recommended in the instructions for use.
  • Do not replace foodstuffs in original container. Dispose of immediately.
General first aid information
  • In case of eye contact: Wash out eye with plenty of water, holding eye open if necessary. Seek immediate medical advice.
  • If swallowed: Wash out mouth with water, drink some fresh water. Do not induce vomiting. Seek immediate medical advice.
  • In case of inhalation: Remove person to fresh air.
  • In case of skin contact and burns: Wash affected area with plenty of water for at least 10 minutes.
  • In case of doubt, seek medical advice without delay. Take the chemical and its container with you.
  • In case of injury always seek medical advice.
Advice for supervising adults
  • The incorrect use of chemicals can cause injury and damage to health. Only carry out those experiments which are listed in the instructions.
  • This experimental set is for use only by children over 12 years.
  • Because children’s abilities vary so much, even within age groups, supervising adults should exercise discretion as to which experiments are suitable and safe for them. The instructions should enable supervisors to assess any experiment to establish its suitability for a particular child.
  • The supervising adult should discuss the warnings and safety information with the child or children before commencing the experiments. Particular attention should be paid to the safe handling of acids, alkalis and flammable liquids.
  • The area surrounding the experiment should be kept clear of any obstructions and away from the storage of food. It should be well lit and ventilated and close to a water supply. A solid table with a heat resistant top should be provided
  • Substances in non-reclosable packaging should be used up (completely) during the course of one experiment, i.e. after opening the package.

FAQ and troubleshooting

My picture didn’t turn out well. Why not?

The lamp you use in this experiment is very important. This experiment works best with fluorescent or LED lights with a capacity of 10 watts or more. If you don’t have an opportunity to use another lamp, try leaving the tray with the template under your lamp for 4-6 minutes.

Can I use ordinary paper (not from the set) to make my picture?

The paper in the set is slightly alkaline because copper ascorbate becomes light-sensitive in an alkaline environment. Therefore, a plain paper will not yield such beautiful results. But you can always try it out anyway to see what happens!

The edges of the pattern have risen. What should I do?

Yes, this can happen, but it won’t necessarily impact the quality of your picture. It’s most important that the center of the template be tightly pressed to the paper.

If you aren’t satisfied with the result, try repeating the experiment.

Part of the copper ascorbate spilled out onto the tray when I applied the template.

That’s okay! Excess solution can sometimes spill onto the tray. Place the tray with the template under the lamp and continue the experiment.

How can I preserve my print?

Dissolve half a teaspoon of baking soda in a cup of water. Rinse your print with this solution.

Step-by-step instructions

Prepare a film negative and a sheet of paper from the set. Additionally, prepare a bright lamp.


First, create a compound called copper ascorbate by combining copper sulfate CuSO4 and ascorbic acid.


Copper ascorbate is not sensitive to light on its own, but it becomes light-sensitive in an alkaline environment. The paper that we use is slightly alkaline.


The metallic copper will precipitate after exposure to light, but the areas of the paper that are protected by the dark regions on the film will remain unchanged.


You can keep the print once you remove any excess light-sensitive mixture.



Dispose of solid waste together with household garbage. Pour solutions down the sink. Wash with an excess of water.

Scientific description

How does the imprint appear?

When we mix copper sulfate CuSO4 with ascorbic acid C6H8O6, a compound known as copper ascorbate forms, which makes the reaction mixture turn greenish.

Further, copper ascorbate becomes light-sensitive in alkali environments. This is exactly what happens when we pour the solution containing copper ascorbate onto our slightly-alkali paper. When the paper is then exposed to a light source, a photochemical reaction takes place, and the image appears.

Why is the paper alkali?

The paper contains some calcium carbonate CaCO3 as a result of some industrial processes used to produce and treat it. When this compound is exposed to an aqueous solution, it creates a slightly alkali medium, sufficient to make the reaction mixture light-sensitive.

What happens when the mixture is exposed to light?

The copper ions Cu2+ contained in copper ascorbate are reduced to metallic copper. It is this metallic copper that makes the image visible.