Spice up your art with turmeric, sunlight, and a 19th century photography technique
Turmeric is one of the most vibrantly colored spices you’ll ever find and a staple of Indian cuisine, but it can do so much more than flavor your food. Curcumin, one of the main compounds in the plant, has myriad health benefits, and people have used it for centuries to dye fabric.
But curcumin is also a photosensitizer, meaning it chemically reacts when exposed to light. In fact, you can use it to print images using a technique called anthotype, which was developed in the 19th century and uses plant emulsions and sun exposure to create pictures on porous surfaces like paper and cloth.
How to create DIY anthotype images 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, aka whatever you want to print—this could be a flower, a leaf, or something else
- Two small containers
- Sponge (or brush)
- Spray bottle
- Coffee filter (or cheesecloth)
- Measuring spoon
- Measuring cups
- Photo frame
- The sun
- Paper towels
- (optional) Rubber gloves
1. Mix the turmeric powder and alcohol in the container. Turmeric dyes pretty much anything it touches, so we recommend you protect your hands with rubber gloves and cover your clothes with an apron or even a trash bag. The turmeric will also stain plastic containers, so it’s better to use one that is disposable or made out of glass.
2. Strain the mix 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, brush the dye onto the paper and let it dry. Light kickstarts the dye’s bleaching process, which you only want to happen when you’re exposing your image. It doesn’t have to be pitch-dark, though—a closet, pantry, or a dim kitchen corner will do just fine. Brush an even coat of dye onto the paper, ensuring the color is as flat as possible. Once you’re done, wait about 15 minutes for the paper to dry.
- Note: If you do this in your closet, make sure to protect your stored clothes, as turmeric dye could splash and ruin them. If you’re using a flat surface like a tray to dry your paper, it’s also a good idea to put down a layer of paper towels first, so they’ll absorb any excess dye.
- Pro tip: The more fibers in your paper, the better. Recycled or watercolor paper is the 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 to be here, so choose anything you want to leave an impression on the paper. That could be something as simple as pressed flowers or leaves, or as complex as an image printed on transparency film or traced on thin paper with archival ink. If you use a printed or traced negative, it must have thick, heavy lines to block as much light as possible.
- Pro tip: You can try using an actual photograph as your negative—just print the one you want in black and white using your home printer. Keep in mind that regular printer paper will block some light, so you’ll probably need to wait longer for your anthotype to finish.
5. Once you’re satisfied with your composition, place it inside the photo frame. If you don’t have a frame in the exact size you need, don’t worry. Technically, you only need the glass, as it acts as a weight to keep everything in place while letting light through. If you have a large frame you can disassemble, for example, you can use it to expose as many images as you can fit underneath.
6. Expose your images to the sun and wait. Place your images on an even surface under the sun. The amount of time you leave them out will depend on the time of day, the weather, and the level of contrast you want to give your image. If it happens to be a cloudy day, consider extra exposure time.
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How well your negative blocks light is also an important factor. Physical barriers, such as green leaves, will leave a crisp, dark imprint, whereas an image with poorly pigmented lines will let light through, resulting in weak or even non-existent lines. You can experiment with different exposure times and angles in relation to the sun—just make sure you don’t move your negative, as it’ll be hard to place it back in the exact same position and you’ll end up with a blurry image.
- Pro tip: Assessing the color of the paper is a good way to determine if your image is ready. You want the exposed surface to turn from a bright yellow to a pale, lemony hue.
7. Mix a borax solution. Just add the borax and water into the spray bottle.
- Pro tip: Use warm water to fully dissolve the borax.
8. Once the exposure time is up, move your images out of the sunlight. You’ll notice the background color of your image is much lighter than it used to be. Once you remove the negative, you’ll also notice the imprint it left in a much darker color.
- Note: If you like this look, you can stop here and put your new print on display. The problem is that the bleaching process will not stop, and your image will fade away with time.
9. Set 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 of it over the print. The lines in darker yellow will become different shades of orange, red, and brown within 10 minutes.
- Note: Don’t be impatient—spraying more borax solution will make the background react as well, leaving you with a big brown stain.
10. Let your image dry. As with any creative method, anthotype is not a perfect science, and you’ll probably need to experiment before you get exactly what you want. Try different dye concentrations and varied negatives. Maybe see what an extra hour of exposure does to your image, or if the location you use to expose your pictures has any effect on your end results. It’s all part of the fun.
The science behind anthotype
Sunlight is a wave, but it’s also energy in the form of photons. Because curcumin, the chemical that gives turmeric its color, has photosensitizing capabilities, it can absorb these photons.
But absorbing energy doesn’t come for free, and when curcumin molecules get lit, they change by reorganizing their electrons, producing highly energetic forms of oxygen. These new molecules then react with the paper and have a bleaching effect, which is due to the turmeric dye fading away.
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When you spray the borax solution on the anthotype, it reacts to the curcumin, which is more highly concentrated in the areas that were not exposed to the sun—the lines that define your image.
This reaction generates boron-based substances that have a two-fold effect. First, they prevent further bleaching of the dye so your image doesn’t fade away with time and light exposure. Second, they enhance the definition of the image by providing a darker color to the areas under the negative.
Published at Fri, 25 Jun 2021 22:00:00 +0000