Blueprinting Herbs

This summer has been busy indeed, and has left me little free time – it has been a summer of sometimes 16 hour days as I see patients, grow, forage, gather and harvest herbs – and process them into herbal products for storage and use throughout the coming months until next summer.

Something that has been very nice to play with in between my work has been a form of primitive photography called cyanotype or blueprinting. This is a basic form of using light-sensitive paper to take outlines or impressions of things placed on top of the paper, which is left in the sun for 30 seconds to 2 minutes: the sunlight lightens the light sensitive paper, while shadows darken it. When ‘developed’ in water, these prints invert, and the outlines of whatever was placed on the paper become white, and the background becomes blue. This process will be familiar to some people as kits were sold in the ’90s called ‘sunprint kits’ which at one time were quite popular.

This is a really nice technique to use to take impressions of leaves, or the gross structure of plants; it is also nice to use on flowers (especially round flowers in the Compositae with clearly defined petals).

Here are some of my attempts at cyanotyping outlines of various plants:

3-D representation of a Nettle (Urtica dioica)

Edge on view of Yarrow (Achillea millefolium)

3-D View of Yarrow Leaves and Flowers

As you can see, it gives a nice, soft impression of the plants; a sort of ‘energetic’ view of them in their form without all the colour and depth information we see when we look at at normal photograph. I like these imprints because they give a much more vitalistic view of the herbs.

Taking it Further

But you can take it further. The process of using light to transfer shadows onto sensitised paper also applies to negatives. As the name implies, these are colour or luminance inverted images, and will be familiar to anyone who has used an analogue (film) camera. Negatives can also leave imprints on this sensitised paper, though there are a couple of considerations. 1) the negative must be the same size as the final print, and 2) as the name implies, negatives are negative.

To make a negative for printing, I found a digital photograph I wanted to print in cyanotype. I opened the photograph in an image editor (In my case, the GIMP though others such as photoshop or photoplus would work well), and converted it to black and white. Next, I inverted the colours. This print was then printed on my inkjet printer on transparency film; a product that used to be used on top-lit slide projectors for use in lectures, etc.

This gives a transparent negative which looks like this:

This negative was placed over some light sensitive paper, and left in strong sunlight for about 25 seconds, after which it was immediately placed in water to fix the print. I must say I’m rather happy with how well it has turned out.

Coltsfoot (Tussilago farfara) growing down by Brayford Pool, Lincoln, 2013.

It is imperative that the negative be held firmly against the paper so it doesn’t move, blurring the print. For this I placed the layers together in a stack: first down a piece of perspex, then my negative, then the light sensitive paper, then a cardboard backing. Held tightly together in sunlight, then the light sensitive paper extracted and developed. If you over or underexpose a print, you will end up with a dark or pale print. Blurring is obvious if the stack gets moved while it is being exposed.

I intend to do much more experimentation with this process as I’ve really enjoyed seeing how it brings a different side to my collection of photographs of herbs, and just what different qualities the process highlights that are missed on my normal ‘snaps’ of medicinal plants!