Hammered Leaf Prints Made Fast with Iron Solution

Every May when the trees come into leaf, I find myself full of enthusiasm for their loveliness and inclined to start collecting some for hammer printing. Then I work away on a piece of cloth and soon remember hammering is a noisy business that rapidly grows dull and find I've chosen the soft, squashy kinds of leaves which get mashed into the fabric or dryer ones that barely leave a mark, no matter how I thump them. A lot of trial and error gets repeated every year for transient rewards, having found from past experience that the pretty fresh green hammer leaf prints will fade to pale beige within a few months of exposure to light. 

This year, I was encouraged to experiment again after checking my friend's curtains. Last year, I hammer printed leaf borders for them on mordanted fabric, then dyed the fabric in a bath of meadowsweet flowers with added iron, which turned the prints into brown silhouettes. Rather to my surprise, they haven't faded despite the sun shining through them all year, the curtains look much the same as when we hung them up last May. It seems to me that the leaf juices must have been able to pick up and concentrate the iron that was in the dye bath, as I know iron is a particularly lightfast mordant for plant dyes. This year's experiment was intended to find out whether it is necessary to premordant the cotton fabric in order to make iron hammerprints permanent.

First I mordanted one piece of cotton curtain fabric by simmering it for an hour in a solution of aluminium acetate at 5% the weight of the fabric. Then I made a dye bath by simmering 100g of silver birch leaves in water with a teaspoon of soda ash to increase the pH. Next, I collected leaves and wedged a board on a garden wall to provide a solid surface for hammering.

Using an old shirt to lay over the leaves, which were laid reverse side down on my curtain fabric, I thumped away until the juices had soaked through the shirt showing a complete leaf shape, lifted away the shirt then peeled off the leaves. After that, I did much the same to two more pieces of the same fabric which hadn't been mordanted.

One of the unmordanted pieces was just heated in water with a splash of dissolved iron. The other went into the birch leaf dye bath together with the mordanted piece and a slug of dissolved iron.

And here is how they turned out. On the left, the alum premordanted fabric has taken up the birch leaf dye with iron as a khakhi background colour and the leaf hammer prints have taken up both the modified dye and extra iron and gone brown. In the middle, the unmordanted cloth that went into the dye bath has picked up a tinge of background colour while the prints have gone brown. Finally on the unmordanted cloth that was heated in iron and water only, you can see the leaf juices in the hammer prints have taken up iron from the water to make grey silhouettes of variable darkness, presumably according to their affinity for iron.

Japanese Acer leaves make a pink fresh print with no apparent colour along their veins, yet the juice in the veins must picking up more iron, as the veins come up much darker than the rest of the leaf.

In future, I think I shall experiment more using unmordanted cloth with just an iron and water bath. The leaf prints go black within ten minutes of heating and you can rinse the cloth straightaway, getting rid of most of the residual iron on the fabric without washing out the leaf shape. Quick and easy method for making rather a striking contrast print. Might be nice to put a single leaf silhouette on a shirt. Or cover up a stain on the front.