Make an Easy Indoor Exposure Light for Cyanotype Printing

While the sun is perfect for cyanotypes, indoor exposure can be a viable option, especially during a cloudy day or for those without easy access to direct sunlight. Here’s a simple DIY method to make an indoor exposure light for Cyanotype printing. My tutorial for cyanotype fabric printing has been so popular; I can now print any time of day…

feature image cyanotype with uv light

I love the sun but…

When I get an idea I want to follow through and the sun does not always cooperate! I was also getting a bit nervous carrying the piece of glass covered boards outside multiple times. This led me to make a simple exposure light system that would be very consistent and reliable. I can now produce my cyanotypes in just one work area without a sunny day.

black light flood light for exposing

I researched and found much recommendation of using a LED UV Black light floodlight. This brand (Everbeam) uses 50 watts. The Wavelength of 365nm falls into the UVA category. Sunlight is mostly UVB with about 10-20% UVA. The risk of the UVA is minimal, but looking into it directly for extended periods in not recommended.

The light spreads outward at 120º so the size of area able to expose can be adjusted to different boards sizes. The further away will make the strength less so exposure testing should be done.

purple flood light 365nm 50 watt

This light has a handle that can be used to mount where desired. Since I may change my arrangement I made a simple cardboard box to cover the prepared cyanotype media.

Supplies to make an exposure box:

Since I wanted to be able to expose the cyanotype without any light spillage I used a basic box. Be aware that there may be some build up of heat of left for long extended periods. The switch is conveniently located on the lamp cord for easy shut off.

box lined with tin foil

The top of the box has a hole cut to the size of the frame of the lamp. I can easily lift off the light to check the process of the print procedure.

To make the light bounce and even I also lined the box with tin foil. This will also make the UV light stronger. Any difference in distance will also affect the strength which will come into play with exposure times.

light mounts in hole top of box

The Cyanotype Exposure Setup:

To prepare the fabric or paper for printing I work in minimal light and keep the cyanotype solution ( mixed solution of ferric ammonium citrate & potassium ferricyanide, Jacquard cyanotype kit) in light-proof jars (cover jars with black electrical tape). Keep prepared papers/fabric in dark bags before use since they are light sensitive. This much like working in a darkroom but not as sensitive.

It is not necessary to be in complete darkness so I usually have a small indirect light on while I work quickly. While fabric & paper dries I place it in a dark closet or cupboard.

light set in place

Exposing the prints:

Once prepared I place the boards under the box to expose, making the cyanotype process even more simplified.

plants for cyanotype

Gee, what can I use?!

If you are new to cyanotype printing then you may be using the much-loved botanical specimens, leaves & flowers to create interesting silhouettes. Once you start to feel more confident the ‘sky’s the limit’ with what you can use! Please, be creative and look around for endless possibilities.

plants in position for exposure

Exposure times:

Once the box was ready I decided to make some test exposure times. After coating the fabric and paper with the sensitive solution the board is ready to be covered with glass (or plexiglass) for exposing.

making test timing

To test different exposure times I slid a black board over after each 5 minutes to test 5, 10, 15 & 20 minutes.

results showing minimal differences

Results from Exposure Tests:

After exposing, the print looks quite greyish until it is washed in a tray of clear water. Wash until no evidence of green & yellow rinses from the prints.

The test did not show a huge amount of difference, oddly enough. The top (see prints above) were 20 minutes towards 5 minutes at bottom. I am quite happy with the quick exposures for ease of use, perhaps it’s because the light is pretty close. If you choose a further distance then the area of spread light will be larger but also weaker, so exposure test would be needed.

It is always a magical thing to watch as the print intensifies the blue color in the dip of weak hydrogen peroxide solution.

cyanotype on rocks

Get ready; you’ll be looking at everything you find to print on! I’ll be sharing this method soon!

cyanotype on bisque

Wait, what! I can print on that?!

I keep looking at everything… and find more things to print on! Yes, just wait to see how to print that gorgeous deep blue on ceramic and bisque, not to mention leather. It brings back nice memories of photography class in college. The key photographic process concepts we learned then now apply to the use of Photoshop, imagine that?! Things like ‘dodge’ & ‘burn’!

Also don’t forget that once you discover that you can make your own film negatives with a home printer, there will be even more creative opportunity for amazing prussian blue prints. Thank you John Herschel for the chemistry & printing processes!

beautiful feather prints

There’s no stopping me now… thanks to the use of an indoor version of the ‘Sun’ (my UV light source) I can now print whenever I like! I hope you find this tutorial helpful for continuing your cyanotype arts or as beginners.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

10 Comments

  1. When the “Blue Bug” bites it truly does bite hard and deep. I bought myself the exact same indoor UV light as you’re now using 2 years ago. Absolutely love it. We live on the wet coast of BC so our sunny days are more limited than other geographic areas. I now am experimenting and exploring the endless possibilities of Wet Cyanotypes. The C solution is applied on substrate, leave it wet, choose to place your botanicals on now or after the “fun additives.” Sprinkle of salt, citric acid crystals, turmeric, misting with water, vinegar, even diluted pigments or fabric dyes …. top with some soap bubbles … and finally the glass or plexiglass. Expose to UV, outside or inside. It will take longer to turn that bronze-y shade, maybe up to 8 hrs …. but same rinsing in water, and voila! Possibilities endless. Have fun.

    1. I echo your enthusiasm! First came shibori, indigo and now this cyanotype! I love all the possibilities too! If you want to add some more fun to this; Eco printing is another obsession! I can already imagine it combined! Thanks for joining me and I’m glad you also enjoy the light!

  2. I’ve had the chemicals for a couple of years now but I’ve never even opened them. I tend to do that…buy the materials but either never use them or use them once and forget them! I have a Celluma panel that I used in my esthetics studio that has led lights ranging from blue (465nm) to red (640nm) to near infra-red (880nm).

    I will experiment with it to see if it exposes or burns the chemicals before possibly making yet another purchase of a light.