Turmeric is one of the most colorful spices you can find and a staple in Indian cuisine, but it can do a lot more than flavor your food. Curcumin, one of the main compounds in the plant, has a myriad of health benefits, and people have used it for centuries dye fabric.
But curcumin is also a photosensitizer, which means it reacts chemically when exposed to light. In fact, you can use it for print images using a technique called anthotype, which was developed in the 19th century and uses plant emulsions and sun exposure to create images on porous surfaces like paper and fabric.
How to Create DIY Anthotype Pictures at Home
Time: 10 minutes (preparation), 1 to 3 hours (exposure)
Material cost: less than 25 cents per print
- 1 teaspoon of turmeric powder
- 2 teaspoons of borax
- ⅕ cup or 50 milliliters of rubbing alcohol
- ½ cup of water
- 1 sheet of fibrous paper
- A negative, that is whatever you want to print, it can be a flower, a leaf or something else
- Two small containers
- Sponge (or brush)
- Coffee filter (or gauze)
- Measuring spoon
- Measuring cups
- picture frame
- The sun
- Paper napkins
- (optional) Rubber gloves
1. Mix turmeric powder and alcohol in the container. Turmeric dyes just about anything it touches, so we recommend protecting your hands with rubber gloves and covering your clothes with an apron or even a garbage bag. Turmeric will stain plastic containers as well, so it’s best to use a disposable or glass one.
2. Filter the mixture with a coffee filter or cheesecloth into another container. This will allow you to get rid of the powder, which will allow the dyed alcohol to spread more evenly on the paper.
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3. In the darkest space you have, apply the stain to the paper and let dry. The light sets off the dye’s bleaching process, which you don’t want to happen when you expose your image. However, it doesn’t have to be pitch black – a dark closet, pantry or kitchen area will do just fine. Apply an even coat of stain to the paper, making sure the color is as flat as possible. Once you’re done, wait about 15 minutes for the paper to dry.
- To note: If you are doing this in your closet, be sure to protect your stored clothes, as the turmeric dye could splash and damage them. If you are using a flat surface such as a tray to dry your paper, it is also a good idea to put a layer of paper towels on first, so that they soak up any excess dye.
- Pro tip: The more fibers in your paper, the better. Recycled or watercolor paper is best, but you can use whatever you have, including A4 printer paper.
4. Place the subject of your print (the negative) on the paper. You can be as creative as you want here, so choose whatever you want to leave an impression on the paper. It can be something as simple as flowers or pressed leaves, or as complex as an image printed on transparent film or traced on thin paper with archival ink. If you are using a printed or traced negative, it should have thick and thick lines to block out as much light as possible.
- Pro tip: You can try using a real photo as a negative: just print the one you want in black and white using your home printer. Keep in mind that regular printer paper will block out a bit of light, so you’ll probably have to wait longer for your anthotype to finish.
5. When you are satisfied with your composition, place it in the photo frame. If you don’t have a frame in the exact size you need, don’t worry. Technically, all you need is the glass, as it acts as a weight to hold everything in place while still letting light through. If you have a large frame that you can take apart, for example, you can use it to display as many images as possible underneath.
6. Expose your images to the sun and wait. Place your images on a flat surface under the sun. How long you omit them will depend on the time of day, the weather, and how much contrast you want your image to be. If the day turns out to be overcast, consider additional exposure time.
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The quality of your negative blocking light is also an important factor. Physical barriers, such as green leaves, will leave a crisp, dark imprint, while an image with poorly pigmented lines will let light through, resulting in faint or no lines. You can experiment with different exposure times and angles to the sun – just make sure you don’t move your negative as it will be difficult to put it back in exactly the same position and you will end up with an image blur.
- Pro tip: Evaluating the color of the paper is a good way to determine if your image is ready. You want the exposed surface to change from a bright yellow to a pale lemony hue.
7. Mix a borax solution. Just add the borax and water to the spray bottle.
- Pro tip: Use lukewarm water to completely dissolve the borax.
8. After the exposure time has elapsed, move your images away from direct sunlight. You will notice that the background color of your image is much lighter than before. Once you remove the negative you will also notice the imprint it left in a much darker color.
- To note: If you like this look, you can stop here and show off your new print. The problem is, the whitening process won’t stop and your image will fade over time.
9. Define your image with a thin layer of borax solution. Place your print on a paper towel. Shake your borax solution well and spray a thin layer on the print. The lines in darker yellow will turn into different shades of orange, red and brown within 10 minutes.
- To note: Don’t be impatient: spraying more borax solution will also cause the background to react, leaving you with a big brown stain.
10. Let your image dry. As with any creative method, anthotype isn’t a perfect science, and you’ll probably have to experiment before you get exactly what you want. Try different concentrations of dyes and different negatives. Maybe see what an extra hour of exposure does to your image, or if the location you use to exhibit your photos is having an effect on your end results. It’s all part of the fun.
The science behind the anthotype
Sunlight is a wave, but it is also energy in the form of photons. Because curcumin, the chemical that gives turmeric its color, has photosensitizing abilities, it can absorb these photons.
But energy absorption is not free, and when curcumin molecules light up, they change by rearranging their electrons, producing highly energetic forms of oxygen. These new molecules then react with the paper and have a whitening effect, due to the discoloration of the turmeric dye.
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When you spray the borax solution on the anthotype, it reacts to the curcumin, which is more concentrated in areas not exposed to the sun, the lines that define your image.
This reaction generates boron-based substances which have a double effect. Firstly, they prevent further bleaching of the dye so that your image does not fade over time and exposure to light. Second, they improve image definition by providing a darker color to the areas below the negative.