I love working with Interference colors - it's like painting with candy (which consequently makes me hungry the entire time I'm working)
I am often asked what the difference is between the Iridescent and Interference colors, and how to use the Interference, so I thought I'd write a little post about it.
Iridescent colors are more traditional metallic colors - bronze, coppers, golds, silvers, etc.
While Interference colors are also shimmery, reflective, and for the most part made from the same materials as the Iridescents (coated mica platelets), they are quite translucent and milky in their pure form. They also look different depending on which angle you view them from. Depending on the way light hits these colors, they flip from an opalescent color to its opposite, reproducing the effect of oil on water or the shimmer of dragon fly wings- a natural phenomenon called light interference. When applied over light surfaces, the interference color is more subtle, and the " flip " more obvious - over black and/or dark surfaces, the color is dominant and that flip more subtle.
My favorite way to use these colors is mixed in with other colors, including Iridescent colors. You can get incredibly rich and delicious colors with these, and the possibilities and permutations are pretty endless.
Here's a few ways to make the most of these gorgeous paints.
1) Avoid opaque.
When you're working with Interference colors, mix with transparent (modern) colors rather than opaque (mineral) ones. Transparent colors allow the light to still come through and hit the mica, keeping that shimmer - opaque pigments will cover the mica and you'll lose your pearlescent effects.
Not sure if your chosen color is transparent or not? Here's a great tech sheet from Golden listing which is which (Note: Modern pigments are also called " organic," and mineral pigments called " inorganic." )
2) Consider your sheen.
Matte mediums and gels have a white powder called silica in them, which cuts the natural glossiness of the acrylic binder. When you mix Interference colors with matte mediums, the silica will dampen their light play. Which isn't necessarily a bad thing - for instance, a little bit of Interference color is added in these great faux encaustic recipes. If you're going for a strong pearlescent effect, however, you'll want to stick with gloss and/or semi-gloss mediums and gels.
3) Watch your ratios.
Because mica platelets are so much larger than most pigments, Interference colors tend to be weaker than regular colors. Add smaller amounts of other pigmented colors to your Interference colors to keep your sparkle.
4) Consider your basecoat.
Remember that Interference colors look hugely different on light and dark surfaces, so keep that in mind when layering.
5) Add black.
To produce the brightest colors when working with the Interference colors, try mixing them with a tiny amount of black - this will strengthen the reflected color.
Ideas for use
Like I said, mixing Interference in with other colors is my favorite way to use these paints, but there's lots of different options for use. Here's a few ideas:
1) Underpainting. Use Interference colors as a basecoat to give you a luminous first layer, allowing you to later use subtractive techniques to reveal hints of metallic.
2) Washes. Thin down a Fluid Interference color with water and apply it to a textured surface to gives you a hint of metallic in the nooks and crannies of your surface.
3) Dry brush. Using a dry brush, lightly apply a Heavy Body Interference across the peaks of your surface to highlight texture and create more depth.
4) Glazing. Mix Interference colors with gloss gels and mediums and apply across underpaintings to create interesting colors and reflective effects.
Hope these tips are helpful - if you have any questions, don't hesitate to get in touch!
You can also check out the resources below - a recent article on working with Interference and Iridescent colors from Golden's Just Paint newsletter, and the Golden tech sheets on Iridescent and Interference colors!