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How to create digital negatives for cyanotypes
There are two types of cyanotype prints, the first one is called a photogram, when simply objects and shapes are placed directly onto the coated paper which is then exposed to uv light. In this method there is no need for a camera or transparency film.
The second type of cyanotype is when you create a cyanotype print from a digital negative using transparency film. This method is the one that the rest of this article will cover.
To create a cyanotype print from a digital negative you will need an image manipulation software. There are many free programmes available, some work better than others, but they all have many how to turorials on YouTube. Here are a few: Gimp, Inkscape, Lightzone. We used Gimp for this tutorial, it is a free programme and can be downloaded here. Some of the tools mentioned in this tutorial might be in a differnt place in different versions of Gimp.
Step by step
Open your digital photograph in Gimp by clicking File → Open
Desaturate your image, this will make it black and white. Colors → Desaturate
Invert it, this will make it into a negative. Colors → Invert
Adjust the tones.
The tonal range of a cyanotype print is limited, if you would just print the image as it is now, you would loose detail in the shadow and highlight areas. Also you have to darken your negative considerably to get a good result. We find that applying a curve shaped as on the picture below works best. There are several tutorials on the internet how to arrive to your perfect curve specific for your printer, light source, exposure time and transparencies used. Start with a curve similar to ours and then fine tune it to what works for you.
Open your curves panel by clicking Colors → Curves
You can also further improve your negative by applying sharpening to your image, the Filters → Enhance tab has several sharpening tools to do this.
Next and final step is to flip your image horizontally, because you will place the printed transparency facing ink down on your coated paper for better contact.
Now that your digital negative is ready, you can save it or export it to another file format and print it on a transparency film. We use an Epson printer on the highest quality setting, and Epson premium glossy paper type. You might have to research what the best settings are for your printer and printing dark transparencies. It is important to print on Greyscale, as you only want black and shades on of black in your print, other colours can interfere with the exposure.
Once your transparency is printed and dried, you will need to place it print side down on your coated paper ensuring good contact between them. Any areas without a good contact will result in light undercutting and a blurring effect.
Exposing with a light source like a UV lamp will give more consistent results.