Anthotype Process with Spinach Juice: Sun-Printed Photographs

What to take away

• Spinach juice makes a green anthotype that needs hours to days of direct sun.
• USDA hardiness zone and local summer daylight decide leaf quality and exposure length.
• A 5 x 7 inch print costs roughly $0.40 to $1.20 in materials, mostly paper.
• Judge the exposure by a visible tonal split, then wash and dry in dim light.
• The common failure is fogging from stray light; the fix is a re-coat and a heavier mask.

Spinach anthotype is a contact print made with a chlorophyll emulsion, and it fails slowly rather than suddenly. The anthotype method uses plant emulsions, and spinach is one of the more forgiving sources. The process suits anyone who wants a lower-cost, plant-based alternative to iron-based printing.

What you need before starting

You need fresh spinach and distilled water. You also need a blender, a fine sieve, a soft brush, and cold-pressed watercolour paper. Add a contact frame, a negative or flat objects, and two trays. A kitchen scale helps.

Spinach from a garden in USDA zones 6 to 9 gives stronger juice than supermarket leaves that have spent a week in a bag. Wash leaves, remove thick stems, and use them the same day. Atlanta in June offers roughly 14 hours of daylight, which shortens exposures compared with Seattle or Chicago. A full fitting out a printmaking workspace is not required; a dark shelf and a tray will do.

The sequence

1. Blend 60 g of fresh spinach leaves with 200 ml distilled water until uniform.
2. Strain through a fine sieve or cloth into a dark jar. Press the pulp to recover the green liquid.
3. Brush the emulsion onto watercolour paper in dim light. Coat one even layer, then let it dry flat in the dark.
4. Place the negative or object directly on the dry coated paper. Close the contact frame.
5. Expose in direct sun. Start with 3 hours for a dense negative on a clear June day.
6. Check the image by lifting the frame edge. The exposed area should look pale straw-yellow against deep olive.
7. Wash the print in cool water for 10 minutes, then dry it face up in dim light.

Exposure is not fixed. Cloud, humidity and leaf age can double the time. A spinach print that looks weak at 3 hours may need 6 to 8 hours, or a second day.

Where judgement replaces the recipe

The recipe gives a starting point, but Sun printing covers several plant-based processes that share the same exposure logic. Young leaves in full sun give a faster emulsion. Older leaves or leaves grown in shade give a weaker one. Paper sizing also changes how deeply the juice sinks. A heavily sized paper holds the emulsion on the surface and prints faster; a soft, unsized paper absorbs it and needs longer.

How to tell it is right

A correct exposure shows a clear tonal split. Hold the frame at arm's length in shade. The deepest shadow should read olive-green, and the brightest highlight should read straw-yellow. If both areas look green, the print is underexposed. If the whole sheet looks washed out, it is overexposed.

The wash is the second test. After 10 minutes in cool water, the image should hold its edges. A print that bleeds into a uniform green after washing was not fixed by light enough. For a deeper look at how a related process controls its stages, see cyanotype process stage by stage.

Fixing it when it is not

The common failure is fogging, where stray light reaches the paper under the mask. The recovery is the re-coat and re-mask: wash the failed sheet, let it dry, brush a fresh emulsion layer, and expose again under a heavier opaque mask with a tighter contact frame.

A weak, low-contrast image usually means the negative is too thin or the paper absorbed too much juice. Switch to a denser negative or a harder-sized paper.

What the print costs to make

A 5 x 7 inch print uses about 15 cents of leaves, 10 cents of water and energy, and 20 to 80 cents of paper. Total materials land between $0.40 and $1.20 per print. Buying paper in larger sheets and cutting it down lowers the paper cost. The finished cyanotype print gives a useful baseline for paper and chemical budgeting, even though spinach costs less than iron salts.

Paper weight matters more than brand. A 140 lb cold-press sheet holds a coat without buckling, while a thin student paper drinks the emulsion and can tear in the wash. A farmers market bunch in July often costs less than a cup of coffee and yields enough juice for three or four small prints.

Common questions

How long does a spinach anthotype take? On a clear June day in Atlanta, 3 to 6 hours is typical. In winter or in northern cities, expect 1 to 3 days of direct sun.

Can I use frozen spinach? It works in a pinch, but the juice is weaker and often brown. Fresh leaves give a cleaner green and faster exposure.

Do I need a darkroom? No. You need dim light for coating and drying. A bathroom with the lights off and a towel under the door is enough.

Why did my print turn brown? Spinach chlorophyll degrades with heat and age. Brown prints usually come from old leaves, warm emulsion, or overexposure after the image has already formed. A brown print is usually a sign that the emulsion was old or warm before exposure. If you track printmaking mistakes keep happening, you will see that most anthotype faults come from inconsistent coating, not from bad leaves.