Impatient Anthotypes: High-Contrast, Quick-Exposure Emulsions

The anthotype process transforms everyday plants and food into beautiful, light-sensitive prints, but it is often slow and unpredictable. In this experiment, Mariam Matta set out to explore high-contrast, quick-exposure anthotype emulsions that could offer faster results without sacrificing detail. By testing a variety of plant pigments, alcohol thinners, and toners, she aimed to identify combinations that are both reliable and visually striking and shares the results in this article. More about pH and anthotypes can also be found in the Anthotypes – The Complete Guide… book

Writer and photography / Mariam Matta

“Part of the magic of the anthotype process is the unpredictability and alchemy of common household ingredients—and even food waste.”

I was running a sun-printing workshop at my local makerspace and set out to identify high-contrast, fast-exposing anthotype emulsions. Cyanotype was my gateway to anthotype, partly because the quick results provide near-instant gratification. My hope was to find an emulsion that could similarly act as a gateway for others to explore the anthotype process. So, I did some research, gathered materials, donned my “mad scientist” hat, and began experimenting.

Identifying candidate plants and thinners

The Anthotype Emulsion Database is a fantastic resource. There is an option to sort by time, so I browsed the emulsions in the top two sections (exposure time between 0-4 hours, and 4-24 hours). The candidate plants were whichever I had on hand.

• Spirulina (green, powder)
• Turmeric (powder)
• Matcha (powder)
• Red pepper (in variants of (a) a dried cherry bomb pepper extracted by mortar and pestle, and (b) cayenne powder, both of which are Capsicum annum)

Thinners

For thinners, I’ve read that alcohols tend to extract pigment better than water, so I stuck to various alcohols.
I don’t drink very often anymore, so this was also a great way to make use of some liquor. I ended up using variations of:

• 91% isopropyl alcohol
• Absinthe
• Butterfly pea flower gin (Empress 1908 Indigo gin, to be specific)

The butterfly pea flower gin was one I was particularly excited about, because the butterfly pea flower changes colour from blue to purple in response to the pH shift when lemon juice is added. As we’ll see later, the results were a tad disappointing. Perhaps this is because lemon juice is acidic (low pH), and the most common solutions used for toning anthotypes, such as baking soda, are alkaline (high pH).

Exposure

To test contrast, I used this faux negative that I made with black vinyl, which was cut by my Silhouette Cameo 4 (a digital plotter/cutting machine). I had this leftover from a cyanotype keepsake napkin project, where it was laid over some medium-format black and white film negatives. The negative did slightly shift after I placed a glass pane over it, so if you’re referencing this photo with the results side by side, keep that in mind.

I didn’t measure the exposure time exactly because I was attempting a few different artificial UV sources before settling on a UV lamp that is used to cure gel nail polish. It is not a super-powerful lamp – there are only 24 UV LEDs inside, and I’ve had it for several years. I have a UV test card that is used for checking if sunscreen is needed, and this was the only artificial light source that triggered the test card to change colour (grow lamps were also tested, but I’ve only used them successfully at very close range and for long exposure). I would estimate, at most, a 30-minute exposure, but probably closer to 20.
I feel that overexposure is a null issue with anthotype as compared to cyanotype, and the main point was to find something providing clear contrast in under an hour.

Here are the results of the exposure before toning. The clearest contrast can be found with the turmeric + spirulina and matcha + spirulina emulsions, both thinned in 91% isopropyl alcohol.

The other thinners showed less contrast. The butterfly pea flower gin, in particular, was already disappointing, but I held out hope for a reaction with a lemon juice toner.

The cayenne emulsion fared better than I expected, but was not a clear contender for a short exposure emulsion.

Toners

I used variations of the following toners, sometimes layering them:

• Lemon juice (from the bottle)
• Baking soda (sodium bicarbonate/bicarbonate of soda) in water
• Washing soda (sodium carbonate/soda ash) in water
• Borax (sodium tetraborate) in water*

*Note: Borax is banned in the UK/Europe, but is a bit unavoidable here in the US. Obviously, don’t use it if it’s unavailable to you or if you have concerns, but it is interesting for use with turmeric emulsions because curcumin, the chemical compound in turmeric, is a boron indicator.

Toners were mostly applied by brush (except for the baking soda solution, because I had it in a dropper bottle and just spread it out with a finger).

Results

The following combinations of emulsions and toners were the most favorable results in my experiment, in order of decreasing contrast:

1. Turmeric + Spirulina in 91% isopropyl alcohol, toned with washing soda solution
2. Turmeric + Spirulina in 91% isopropyl alcohol, toned with borax solution
3. Turmeric + Spirulina in 91% isopropyl alcohol and absinthe, toned with washing soda solution
4. Turmeric + Spirulina in 91% isopropyl alcohol and absinthe, toned with borax solution
5. Matcha + Spirulina in 91% isopropyl alcohol, no toner
6. Matcha + Spirulina in 91% isopropyl alcohol, toned with baking soda solution
7. Turmeric in butterfly pea flower gin, toned with 1 layer of lemon juice followed by one layer of baking soda solution.

Conclusions

Other observations, conclusions, and questions from this experiment:

• Of the tested emulsions and toners, the turmeric/spirulina in 91% isopropyl alcohol emulsion toned with a washing soda solution may be most reliable for beginners seeking a high contrast, quick exposure anthotype process
• Absinthe as a thinner seems to consistently result in a more cloudy, painterly finish
• It’s possible that these don’t go great together:
  – matcha emulsion/lemon juice toner
  – matcha emulsion/borax solution toner
  – Cayenne emulsion/BPF gin thinner
• Matcha has the highest contrast without the toners tested here, but it is quite expensive. Spirulina, in general, may function well as an additive that decreases exposure time
• Borax toner produces browner tones, while washing soda and baking soda produce redder tones, with washing soda producing brighter reds.
  The relationship between the alkalinity of the toner and the colour output is non-linear, though, because between the 3, washing soda is the most alkaline and baking soda is the least. Even taking into account that turmeric is a boron indicator, other emulsions that did not contain turmeric still showed decreased saturation with a borax wash. What causes this, and how can it be emulated with an alternative to borax?
• More testing with butterfly pea flower in the thinner of the emulsion could prove interesting. Were there other ingredients in the gin that interfered with the output? What other teas or alcohols that are pH reactive could be tested?

More experiments will be made!

Mariam Matta is an avid DIYer, artist, and writer based in Los Angeles, CA. Her projects take a special interest in the alchemy of trash to treasure and destruction to reconstruction.