• Macs

The Visible Vs The Invisible - Two Paintings In One

Updated: Jun 14, 2018

For someone with a mind like mine, creativity is a bit like the metaphorical thread – I strike upon one idea, get a little obsessed with exploring it, and before I know it, I have journeyed through, and unravelled, several ideas. Sometimes these journeys make a leap to another connected idea like electricity arching from one wire to another. This post explains how I went from trying to up-cycle some old glow sticks, to creating paintings hidden within paintings only visible under UV light.

Firstly, what exactly is UV light or 'Black' Light?

As part of a series of posts on UV, I have delved into the mysterious light spectrum that is UV – an electromagnetic wavelength that sits between 10 – 400 nanometers (check out my post 'What is UV or 'Black' Light? And why we humans are all effectively colour-blind'). Since humans can only see wavelengths of between 390 – 700 nm, the UV spectrum is largely invisible to us. Compared to many insects, birds and fish, we lack a vital photoreceptor which would enable us to see flowers, insects and even gemstones in their full glorious glowing colour.

We are essentially blind to a world of fluorescing markings, patterns and substances.

Crucially that 10nm overlap of the UV spectrum and our vision spectrum allows us the briefest glimpse into this hidden world. However, we need to turn down the lights and use a special bulb which emits a low enough wavelength to saturate what we are looking at.

A UV bulb is black
L: A UV bulb is black. M: A UV bulb fluoresces purple when on. R: The bulb appears much brighter in total darkness.

Using UV light to create 'invisible' artworks.

Whilst researching ways to up-cycle some old glow-sticks (see my post '3 Sense-tingling Ways To Reuse Glow Sticks') I learnt that the liquid in old glow-sticks still visibly fluoresced under UV light even once the glowing chemical reaction had ceased. Around the same time I by chance stumbled across a National Geographic post on the appearance of flowers in UV light – or how bees and other insects really see flowers. Remarkably, some flowers appear to alter their colours and patterns entirely under black light, revealing the beauty of a spectrum we as humans are not normally privy to.

It's a delightful thought that there is an entirely different experiential world out there depending on what frequency your senses are tuned to. That National Geographic article made me wonder if it was possible to paint these pictures of flowers using a combination of normal paints and UV inks – painting the flowers as they appeared during daylight, and then showing their real appearance under UV light. More generally, was it possible to create a painting that looked a certain way in natural light, but could be altered or even augmented under UV light – effectively two paintings in one?

Now for the hard part – painting with Glow-stick fluid!

Freshly inspired, my next challenge was to find out how the glow-stick fluid reacted when exposed to air and being absorbed by paper as well as whether they would mix well with paints.

I created a swatch card which dried quickly to show me which colours were strongest under UV.

It turns out that pink and blue are the brightest, so I would begin working with them.

Glowstick liquid swatch
L: Swatches of glow-stick liquid from four differently coloured glow-sticks. R: Blue glow-stick liquid mixed in PVA glue, to help it set better on the acrylic painting.

Since I prefer to work with acrylic paints, I started with those before trying out watercolours. However, the glow-stick liquid did not mix or set well due to its chemical composition. On the advice from an art-teacher friend of mine, I mixed the glow-stick fluid into PVA glue in order to layer it onto my acrylic painting as a separate layer once the initial painting was fully dry.

My first painting: An acrylic sunset over mountains in normal light, an eerie glowing moonscape under a UV bulb.

I kept my first attempt at painting using glow-stick fluid as simple as possible using only the blue UV ink. I saturated large parts of the sky area with blue UV fluid before painting over it. To add the hidden UV glow over the mountain areas I had to blob the extremely sticky, stretchy PVA glue / glow stick mix over the top. This was very imprecise, but worked well for the rugged nature of the mountains.

My second painting: Watercolour flowers on UV ink soaked backgrounds.

After the challenges of using acrylics, I switched to watercolours. This type of painting was much more tricky and required more precise planning. For the UV effect to work I had to paint the glow-stick fluid onto the paper first. This meant painting the negative space or just the lightest part of the flowers. As with all water colour painting, getting every stoke as accurate as possible was critical since there was less scope to layer the painting and make corrections without completely covering the UV layer.

1) First I painted a basic poppy picture using a mixture of orange and green glow-stick inks. This picture was not meant to National Geographic 'insect vision' perfect - it was simply to see how well the watercolours and glow-stick ink interracted.

water colour poppies with UV

Secondly, I tried my hand at a more complex Morning Glory flower using three types of glow stick fluid – pink, blue and green. This was my attempt at an 'insect vision' painting or how a bee may see the flower versus how humans see it.

Watercolour UV painting

UV and normal Morning Glory flower
L: UV 'insect vision' Morning Glory flower. R: Flower seen in human vision.

Just how easy is it to create two paintings in one?

As a means for up-cycling some glow-sticks, the paintings were a successful and rather fun creative adventure. Imagine them up on a wall with two types of bulb shining over them - UV would certainly add another dimension. However, I did feel that using materials that were not designed for purpose put certain limitations on the images I was able to produce. The glow-stick ink was hard to apply precisely and could not be applied easily over the top of the other paints; making for a less dramatic and intricate effect.

Interestingly, re-creating the UV flowers from the National Geographic article could only be done with certain types of flower, such as the blue Morning Glory shown above. A yellow daisy for example, actually changes colour and fluoresces pink and purple under UV. I would be able to make a yellow fluoresce but only in yellow UV – otherwise I would have to use pink UV ink and the flower would appear pink (completely different!) in normal light.

No doubt with more suitable UV paints, pens and even printer cartridges, alongside more finessing and experimentation I can hone my skills and create some very dramatic and better produced pictures. Watch this space....


 Welcome to Sensorama - a blog to tickle the senses.


This blog is dedicated to curiously exploring the world via the 5 senses of sight, sound, smell, taste and touch.
Our perception of reality is determined by our own senses - and there are millions of sensory experiences out there for us to explore. Join sensorama bloggers Macs and Oliver as we take you on an extraordinary tour of the world all around us through sensory science, experiences, stories and sensations.


Via Sight : Beautiful faces, amazing colours, hidden lights spectrums, optical illusions, incredible animals and emotive art - our ability to see is central to nearly every part of our everyday lives. Yet how often do we stop and take a fresh look at the world? At Sensorama we take a second glance at the everyday, the unusual and the at times invisible.

Via Sound : Hearing is the key to communication and how we interact. Like a heartbeat, it is also highly personal. From thrash metal to choral hymns which make the heart soar - what we love to listen to can determine our mood, emotional state, and sense of identity. At Sensorama we take a in depth listen to the beats of life.  

Via Smell : Smell is the sense that much of the animal kingdom relies on to find food, sense danger or attract a mate. It is the sense which can evoke a long distant memory and silently affect our perceptions and behaviours. At Sensorama we pay attention to what’s right under our nose.  

Via Taste : What some cultures find delicious, others find repulsive. Taste is so often a matter of, well, taste. Starting as an evolutionary way to avoid poisoning, we have mastered the sense of taste to tickle some of the strongest pleasure centres of our brains. At Sensorama we search out the tantalizing and delicious.


Via Touch : Touch can be anything from comforting to terrifying and take us anywhere from excruciating pain to heightened ecstasy. As humans, we feel everything but so rarely pay attention to what our bodies are telling us. At Sensorama we get hands on with all the textures of the world.

Want to contribute to Sensorama?
We are open to suggestions including any new London experiences to try.


Visit our about us page to get in touch.