Lately, I’ve been experimenting with interference colours. Daler and Rowney make some and I bought a few.
They aren’t actually paint, they’re a medium with unusual properties. They interact with the surface colour they’re painted on and produce a shimmering effect, when painted over darker colours. When painted over lighter colours, they sort of make the colour a little reflective, giving it a soft glow. You can mix the interference colours with ordinary acrylic paints and get some unusual effects, especially as the interference colours act as tints, rather than colours.
Here’s a painting I made this week using interference blue tint and interference violet tint. It took me less than 90 minutes (probably just over 60, in truth).
The background is some phthalo turquoise, a touch of tinting white in places and the interference colours. I probably used twice as much of the interference colour as regular colour, in the background. I used a one inch round brush and laid it on very quickly. Then I used one of my effect palette knives that looks a bit like a cat’s claw to scratch back through to the canvas to reveal some white scratch marks in the background. What I loved was the ghostly glows you get in the background. Spooky.
The figure of the model was sketched in paint, direct to canvas, using straight phthalo green (from the Atelier Interactive range). I sketched her in using a number 8 filbert brush. I don’t sketch in charcoal or pencil anymore, because both interfere with the purity of my colours, especially the lighter ones.
To paint the tones of the flesh, I used a combination of cobalt green and permanent sap green. In places, I also used some tinting white to lighten some areas and I used green black for the dark areas. You read that correctly. I used greens. The same ones you use in landscape paintings to represent trees. So how come the figure looks like a human, instead of a Martian?
This is the tricky part. I outlined the lit edges of the figure in jaune brilliant. It’s a very pale orange and one of my favourite colours in my box. It’s a lovely shade. There is a thin outline on the contours. In some places, I also added a line of tinting white and blended the orange with the white, where I wanted to soften the edge. I also placed a little of the jaune brilliant on the peaks of muscle groups I wanted to highlight, using a dry brush technique. It’s barely there. Just suggested.
The hair was painted in green black, mainly, with some tinting white to produce the greys. I used interference blue tint in the hair to tie the tone of the hair to the glowing turquoise background.
The final touch was to go over areas of the skin tone that were green with some of the interference colours (blue and violet). I didn’t use much. I used just enough to give the skin tones some shimmer, under lit conditions.
Here’s where something accidentally magical happened. Because the leading edges of the figure (the highlights) were flesh-toned and the rest of the green figure was similar in tone to the background, the illusion produced is that the whole figure is skin toned, but it is being seen in a greenish blue ambient light – the same turquoise as the background, in fact. The glow of the background acts to convince you that it is the light source and that the darker green areas of the figure are in shadow. There is just enough interference colour in the skin to lift it and brighten it. The very small areas of skin tone act to fool the brain into thinking the whole model is skin toned, even though it wasn’t painted in skin colours!
I didn’t expect that effect. I know, intellectually, that I painted the model in various shades of green paint, yet I see a skin tone in shadow, when I view the finished painting. It’s a lovely shadow effect, in my opinion.
To finish, I painted some shadows on the ground where the model sat using neat phthalo turquoise. Those have the effect of tying the model to the ground, instead of making her look like she’s floating in mid air.
I’m really happy with the effect I got. There is a lot to be said for interference mediums, with their ability to subtly bend the tone and colour of the paint, in the right light. It makes the colours look more vibrant and exciting, while maintaining some subtlety. What I was really pleased with, though, was how the brain tries to fill in a skin tone, when only the edges are actually painted in a skin tone. That’s an amazing illusion, in my view. I think the interference colours are what finish that subtle shadow effect and give the painting a suggested chromatic unity.
So, give interference colours a go. You can get some very nice things on the canvas with them, if you are willing to experiment.
(By the way, I am not sponsored or endorsed by any of the paint manufacturers mentioned. I choose my materials and pay for them with my own money.)