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Capillary Action Sun Prints

Up to 1 hour


Ages 8+

What Will You Learn?

Until digital cameras came along, most people took photographs on film and printed them out on paper. But one of the first types of photograph, known as sun prints, lets you make an image directly on paper—no film or camera needed! Early photographers like the British scientist Anna Atkins made sun prints to record plant specimens. Atkins took ferns, leaves, and flowers, lay them on the paper, and put them out in the sun. Special chemicals in the paper turned dark wherever the energy of the sun hit them. Areas that were covered stayed light. Artists still make sun prints—or to use the fancy name, heliographic art—to create special effects on paper or fabric. 

A sun print is a type of negative image because the light and dark areas are reversed. Film cameras also produce negatives. When you press the button, the shutter opens and lets light in. Wherever the light hits the film, the film turns dark. To make a print, you have to reverse the process by shining light through the negative onto light-sensitive paper. In the final product, the light and dark areas are back to normal. 

A true sun print is sometimes called a cyanotype, because the special ink used turns the paper or fabric cyan, a type of blue. But you can get the look of a sun print by covering a piece of fabric with ordinary acrylic paint—and make it any color you like! In this version, the paint doesn’t go through a chemical change. Instead, the wet paint is wicked away from areas that are wetter to areas that are drier. The sun dries the parts of the fabric that are uncovered faster than the parts that are covered. This leaves a lighter “shadow” behind that is shaped like the object you placed on the fabric, just like in a real sun print. 

The wet paint moves because of capillary action, the ability of water to move inside materials containing a network of small openings. (A capillary is a very narrow tube.) It’s the same thing that happens when you use a towel to wipe up a puddle of water on the kitchen counter. All substances, including water, are made up of tiny molecules. Molecules are the smallest part of a substance that still acts like that substance. Water molecules tend to stick together, which is why water forms drops and puddles with smooth rounded edges. Water molecules are also attracted to some other materials, like cotton cloth. When you blot a puddle with a cloth, the pull of the cotton is stronger than the force holding the water molecules together. The water gets pulled into the spaces between the threads in the cloth. These openings act like little straws that suck the water in. If the cloth is damp, it can pick up water even faster, because the water in the cloth also pulls on the water in the puddle. 

Try making a Capillary Action Sun Print and see what kind of effects you can create!

Wet Your Cloth

Step 1

Wet your cloth by first dipping it in a cup or bowl of water and then squeezing it out or by spraying it with water. It should be damp but not dripping.

Step 2

Spread the cloth out on the work board or table. Smooth out the cloth as much as possible. It should stick to the plastic, which makes it easier to work on.

Paint Your Cloth

Step 3

Put some paint in a bowl and mix it with an equal amount of water until it is very thin and runny. (For softer paint, use fabric paint, or add textile medium instead of water.)

Step 4

Dip the brush in the paint and cover the fabric well. For multiple colors, apply colors in separate areas and let the edges of each area run together. You can help them blend by spraying additional water where the colors touch. 

Add Objects to Your Cloth

Step 5

Arrange your objects on the fabric. Flatter objects that are touching the fabric will leave sharper outlines. The shadows of objects that are farther away will be lighter and fuzzier. 

Step 6

Set your arrangement out in the sun to dry. Check on it every 15 minutes or half hour, depending on how hot and dry the air is.

Step 7

Gently peek under one of the objects to see if the fabric is still wet underneath. If it is, let it dry a little more and then check again. 

Step 8

When the cloth is completely dry, remove the objects. You should see the shadows of the objects where the paint was wicked away. 

Set the Paint

Step 9

If you used acrylic paint, iron your shadow print or throw it in a clothes dryer to set the paint. (See “Tips for Working with Paints and Dyes” at the beginning of the chapter.)

Step 10

Then display your print in a frame, or sew it onto a tote bag or throw pillow. Washing your print is not recommended.

What's Next?

You can turn a photograph into a Capillary Action Sun Print using a clear plastic negative.

Step 1

First, scan your image or open your photo file in a photo editing program and convert it to black and white.

Step 2

Then increase the contrast so there are strong areas of light and dark.

Step 3

Finally, invert (reverse) the dark and light areas to create a negative.

Step 4

Print out your image onto a sheet of plastic transparency film. (A copy shop can do this for you.)

Step 5

Tape the plastic sheet to the glass of a picture frame. Set the frame above the fabric on little “feet,” to allow air to get in and water vapor from the evaporating paint to get out.

About the Book

Enjoy this project? T-Shirt Yarn Knotted Headband is just one example of fun and innovative projects you can find in the book Fabric Inventions by Kathy Ceceri. Fully illustrated with easy step-by-step projects, this fun book starts with the basics of sewing and knitting before moving on to more complicated topics such as silkscreen and electronic circuits in your wardrobe. By completing the projects, you’ll soon be able to create your own amazing fabric and fiber inventions!

Kathy Ceceri June 4, 2021
Kathy Ceceri is a STEAM educator and the author of over a dozen books of hands-on learning activities with a focus on science, technology, history, and art. She has taught live online workshops for Maker Camp, written beginner-level tutorials for companies including Adafruit Industries, and worked with the Girl Scouts of the USA to develop robotics badges and a cybersecurity challenge. Formerly the Homeschooling Expert for (now ThoughtCo), Kathy teaches enrichment workshops through schools and libraries, and offers classes directly to families through SEA Homeschoolers. Check out Kathy's books in MakerShed and on Kathy's site. Follow Kathy's works-in-progress and interesting links on Twitter and Facebook and in the group DIY Homeschool. Watch the trailer for her online classes here!