Watercolor already has a beautiful, flowy look—but what if you could add shimmer too? That's where iridescent medium comes in. I recently tried using Winsor & Newton's version, and I'm sharing exactly how it changes your painting.
From tulip demos to sparkle-filled swatches, I'll walk you through how this medium works and how it adds magic to watercolor!
Contents
What Is Iridescent Medium in Watercolor Painting?
Before diving into the paint, let's start with what iridescent medium is.
Key Features of Iridescent Medium
This medium is thick and filled with tiny metallic or pearlescent particles. When mixed with watercolor, it adds a sparkle that reflects light beautifully. The shimmer reminds me of crushed rock or geode sparkles—so pretty!
It's not just a glaze. It actually changes how your paint behaves. The texture is thicker than water, which affects how colors bleed and blend. But don't worry—it still keeps that signature watercolor softness.
Winsor & Newton Iridescent Medium Overview
In my demo, I use the iridescent medium from Winsor & Newton. My bottle's an older one, but their newer version has a different look, so keep that in mind when shopping!
What I love most is that this medium works with any watercolor brand. That means you can take any of your current colors—whether Winsor & Newton or not—and turn them into shimmering shades. Hundreds of options instantly become iridescent. Isn't that awesome?
Iridescent Medium vs. Traditional Watercolor: Full Painting Comparison
To see the true difference, I painted two tulips—one with iridescent medium and one without.
Watercolor Tulip Demo Without Iridescent Medium
Let me start with the control tulip. I use a simple wet-into-wet technique here. First, I wet the paper in the shape of tulip petals.
Then, I drop in some Permanent Rose that I've thinned with water. I don't overwork it—I just let the pigment bleed and do its thing.
That's what I love about watercolor—it often paints the picture for me. The colors bloom and spread in natural, unexpected ways.
For the leaves and stems, I use Green Gold.
To add contrast and depth to the petals, I mix in Permanent Alizarin Crimson. I also darken the leaves by blending a dot of Winsor Violet into the green.
This tulip painting comes together quickly. The bleeding, the flow—it all works beautifully. It's soft, organic, and full of life.
Painting with Iridescent Medium for a Sparkly Finish
Now, let's get to the fun part—adding iridescent medium! I pour some of it into a palette and immediately notice its thickness. You can see tiny reflective flecks suspended in it.
I mix some medium with water, and then I repeat the same wet-into-wet process. But this time, instead of just water, I drop Permanent Rose into the iridescent mix. I also stir some medium directly into the Permanent Rose before applying.
What a difference! The paint still flows, but less freely because the medium is thicker.
I help it along with my brush, but I still get that nice, soft, bleeding effect.
I also mix in some Permanent Alizarin Crimson again—and it blends just how I like!
Even though the medium changes the texture a bit, it doesn't ruin the watercolor flow. It just adds sparkle.
From my angle, I can see the shimmering effect immediately. So, I include some close-up views to show you the sparkle that's happening in person.
Side-by-Side Results: Matte vs. Iridescent Watercolor
Here's what I see when both tulips are done:
- The left side (without medium) has a matte, soft finish.
- The right side (with medium) sparkles with little light-catching flecks.
As I paint, I see the sparkles move and settle into the paper—a satisfying thing to watch! I love how it turns a standard flower into something magical.
Watercolor Swatch Test with Iridescent Medium
After the tulip test, I decide to swatch with a darker color to see more contrast.
Creating Color Swatches with and without the Medium
I use Winsor Violet for this test. First, I paint it plain—with a bit of water—then blend it to the side to show how it softens.
Next, I mix in a generous amount of iridescent medium and try to match the darkness of the first swatch. I need to add more paint because the medium has a slight white tone—it lightens the pigment.
Notable Changes in Texture and Light Reflection
The results are fascinating:
- The paint with iridescent medium holds the brush strokes more.
- It still blends well, but it's not as watery.
- Sparkles settle evenly throughout the stroke, creating that mica-like look.
To me, it looks like tiny crystal shards in the paint—really beautiful. It's almost like painting with crushed gemstones!
How to Add Iridescent Medium on Top of Dry Watercolor
There's another way to use the medium—and it's super simple.
Using Iridescent Medium as a Shiny Top Layer
You can apply the medium over a completely dry watercolor area to enhance the shimmer. Just brush it on as is—no need to mix it with paint.
This method creates a bolder sparkle, especially if the paint underneath is already vibrant.
Finish and Texture After Drying
Once dry, the surface has a slight shine. It's smooth, and the sparkles are locked into place. I use a blow dryer here, and the finish still looks gorgeous.
I also test a lighter wet-into-wet wash using less paint and more medium. This time, the sparkles move around more since there's less gum arabic to hold them in place. It creates a dreamier, more fluid effect.
The Bottom Line
Adding iridescent medium to watercolor is such a simple way to boost your painting. Whether you mix it in or layer it on top, the shimmer creates a new kind of magic. Try it on your next floral or abstract piece—see how it changes the way your colors dance on paper!