I work a lot with heliographic prints, also known as sun prints, as a means of making an image on fabric. The basic procedure is simple: paint is applied to fabric, an object is laid on top of the paint, and it's placed in the sun to dry. As the fabric dries, the paint wicks out from under the object, leaving an image behind. It's a lot of fun to experiment with, and I'd like to share a few variations that can lead to interesting results. Here's an example of prints set out to dry, with plume poppy leaves on them:

All of these prints were done with Setacolor transparent paints; I've had consistently good results with them. The paint is thinned with water at a ratio of about 1:1. Slightly more paint can be used for more intense color, but if too much is used, it won't wick well on the fabric. If the paint is thinned excessively, the image will be muted. I use leaves in my work, but you can also experiment with paper or foam cutouts, found objects, etc.

TYPE OF FABRIC

Silk fabric tends to give more vibrancy of color.

Here's a print on textured silk:

And here's the same leaf, same paints, on pfd cotton:

You don't need to confine yourself to a white ground fabric. This small quilt started with a print on a pale pink silk:

MIXING COLORS

The mood and impact of the image can be greatly changed by the use of color. Here's a monotone image, done with green paint only:

Here's the same locust leaves, done with a mix of two colors this time:

The use of more than one color can be handled in two ways. Both colors can be applied to the fabrics in a random fashion before the leaves are applied, as in the card above. Alternatively, the lighter color can be painted on first, the leaves applied, then the darker color(s) applied around the leaves just where desired, as in the card at right:

How the paint spreads and mixes is also influenced by how wet the fabric is when the paint is applied. I prefer barely damp fabric, but it's worth experimenting with dry fabric as well.

DRYING METHODS

The quickest and easiest way to make heliographic prints is on a warm sunny day with low humidity. The edges of the prints turn out crisp and exact. But prints can still be made in less than optimal conditions. Warm and dry indoor conditions will also work, although there will be subtle differences in how the paint spreads. This print was made indoors near the heat of a coal stove.

Another interesting situation is presented by working with large leaves. In less than ideal conditions, the paint around the edges of the leaves will wick out, but in the interior it will remain wet. The leaf can be removed and the paint allowed to air dry, or it can be rinsed out at this point to leave a white center for another variation:

EMBELLISHMENT

Finally, a print is never finished until you decide it is! You can always go back in with more paint to enhance or downplay certain elements of the design. This card was enhanced with gold acrylic paint, mixed with textile medium, applied after stitching:

Have fun with your own experimentation.