Shiny! QoR Iridescent and Interference Watercolors

From its introduction, QoR offered three shimmery shiny special effect colors in tube format: Iridescent Pearl, Iridescent Silver, and Iridescent Gold. The summer of 2022, QoR added three Interference paints available in the “Reflective” six pan set: Interference Violet, Interference Blue, and Interference Green. The original three Iridescent watercolors are also part of this half pan set. This article will focus on these shiny paints, and show some of the aesthetic possibilities they offer.

QoR Iridescent and Interference paints — Image 1: Vertical applications of three Iridescent and three Interference paints, with mixes between adjacent paints. Left to right: mix of Iridescent Gold and Interference Green, Iridescent Gold, mix of Iridescent Gold and Iridescent Silver, Iridescent Silver, mix of Iridescent Silver and Iridescent Pearl, Iridescent Pearl, mix of Iridescent Pearl and Interference Violet, Interference Violet, mix of Interference Violet and Interference Blue, Interference Blue, mix of Interference Blue and Interference Green, Interference Green, mix of Iridescent Gold and Interference Green. On Shizen Design Professional Grade Black Watercolor Paper, Rough, 140 lb (300 gsm)

What they are:

QoR Interference and Iridescent paints use pigments formed by coating mica flakes with Titanium Dioxide. Iridescent Gold is an exception, and has both an iron oxide pigment and Titanium Dioxide over the mica. Coating the thin, translucent, and reflective mica platelets with very thin layers of pigment creates a situation where light reflects and refracts between the microscopic layers. The thickness of the pigment layers, the nature of the pigments used, and the interaction with light results in the different colors and effects we see. Other than the coatings on the mica, there are no pigments in these paints. Their reflective nature means the Iridescent and Interference paints cannot be read in a spectrophotometer. Because of this, they have a lightfast ratings of “NA”. All six of these watercolors granulate.

Image 2: Top row shows frontal view of paints, bottom row shows paints with lighting and viewpoint highlighting their vibrant color-changing nature. Shown from left to right: Interference Green, Interference Blue, and Interference Violet. Each is shown on black and white paper. Throughout this article, all examples use 140 lb (300 gsm) cold press watercolor paper. Unless otherwise stated, the white watercolor paper is Hahnemühle The Collection and the black paper is Legion Stonehenge Aqua Black Watercolor Paper.

Interference paints visually sing when used in a transparent manner, and their colors shift depending upon the viewing angle and lighting (Image 2). The same diluted wash on top of black or white will appear totally different. Over white paper, Interference washes are more subtle and have a tendency to flash the complementary color. Over black paper, these are strong and vibrantly colorful paints with an unapologetic shimmer. Interference watercolors are most beautiful when used thinly as a glaze or wash. Thickly applied in masstone, the Interference paints may appear whitish and opaque.

Image 3: The top row shows frontal view of paints, bottom row shows paints with lighting and viewpoint highlighting their reflective shimmery nature. Each paint is shown in paired columns, white paper on left and black on the right. From left to right: Iridescent Silver, Iridescent Pearl and Iridescent Gold.

Iridescent paints create beautiful, slightly reflective surfaces when painted out transparently (Image 3). When used opaquely, they can provide a solid reflective surface with the appearance of glistening gold, silver, or opalescent pearl. These paints are true to color on black or white paper, although their color can appear stronger on black. Iridescent Silver is a mixture of Iridescent Pearl and Carbon Black (PBk7), so the Silver and Pearl can look alike when glazed over a black surface.

Mixing with other colors

Interference and Iridescent QoR paints may be mixed with other colors. These reflective paints readily separate out in multi-color washes, so stirring often and thoroughly is important when loading a brush. Transparent paints are better mixing partners since they will not cloud the reflective nature of the coated mica platelets the way an opaque paint addition might.

*Image 4: Paint mixes are paired vertically in columns, on black paper above and white paper below. The same wash mix was used for both types of paper.* Starting from the left, Interference Green mixed with Pyrrole Red Medium, Interference Violet mixed with Green Gold, Interference Blue mixed with Yellow Ochre. On dark paper the Interference color dominates, on white paper the non-mica paint is most easily seen. In person, both paints are visible to some extent over each paper.

One beautiful aspect of the Interference paints is the mutability of what is seen, or available to be seen, in a single painting. A viewer’s perception of reflective shimmer and color in a single painting can change depending upon lighting and point of view. The possibilities expand further when an Interference paint is combined with non-Interference paints. On black paper, the Interference paint tends to dominate while against a lighter background, the non-Interference color might easily take charge (Image 4). Mixing with complements may emphasize color variance in what a viewer sees, while additions of the same or analogous colors create more subtle differences. When an interference paint dominates in a wash, that paint’s mutable reflective color shimmers against the stable background of the added color. When the non-interference paint prevails, the result may be a field of translucent color with a glistening reflective veil that appears and disappears as the lighting or view point shift.

Interference watercolors have a low tint strength, so pay attention when mixing with other paints and only add a tiny bit of the other color at a time, mixing and testing between each addition. QoR Iridescent watercolors are stronger in tint strength than the Interference paints, but care should still be taken when creating mixes.

Image 5: Separation of paints while drying. Diluted mixes of Iridescent Gold mixed with Quinacridone Magenta and of Iridescent Gold mixed with Ultramarine Blue. White paper was placed on a flat surface, and a well-stirred diluted mixture was poured over the surface. Paint formed a puddle and was allowed to dry untouched. During drying, the paints moved and separated. Photographed twice to show how appearance can change with lighting.

When puddles of diluted mixed paint are poured on watercolor paper, the Iridescent or Interference can separate out from other pigments. The examples in Image 5 show a mix of Iridescent Gold with Quinacridone Magenta and with Ultramarine Blue. Perhaps because the Ultramarine granulates, its gold partner appears in scales and wisps rather than as a mostly solid mass.

Image 6: Left and center, a mix of Iridescent Pearl and Ultramarine Blue on black and white paper. Right, a mix of Iridescent Silver and Ultramarine Blue on white paper. Paint ratio in each mix is about 1:1. There is an opalescent rainbow of tiny sparkles and a dappled blue granulation texture over all three surfaces. These two qualities show most clearly on the black paper. Due to the addition of black in the Iridescent Silver formula, the Silver mix looks a little cooler and grayer in comparison with the Pearl mixture.

Adding Iridescent Pearl to a transparent watercolor will endow that color with a pearlescent quality (Image 6). This opalescent quality may be striking or very subtle, depending on the mixing ratio, dilution, and surface over which the mix is placed. When a very small amount is used, Iridescents and Interference paints can be subtle enough to only be noticed under certain lighting or in specific viewpoints. Using them this way is like including a lovely surprise for the viewer to discover.

Glazing

Image 7: Iridescent and Interference colors glazed over vertical columns of other colors. Columns left to right: Payne’s Gray, Burnt Umber (Natural), Benzimidazolone Yellow, Phthalo Turquoise, Ultramarine Blue, Dioxazine Purple, Quinacridone Red Light, Quinacridone Magenta. Rows top to bottom: Interference Green, Interference Blue, Interference Violet, Iridescent Pearl, Iridescent Silver, Iridescent Gold

Interference and Iridescent QoR paints may also be layered in washes over other colors (Image 7). Due to the mica, great care should be taken when glazing over these reflective watercolors as they may lift with the application of a wet brush.

Drawing with a dip pen

*Image 8: Drawing made with Iridescent Silver, Pearl, and Gold and Interference Green, Blue, and Violet applied with a dip pen to black watercolor paper.*
*Paints were diluted to be liquid enough to flow but also retain a pleasingly intense color.*

A simple dip pen with a replaceable nib works as a calligraphic tool to draw and write with these paints (Image 8). We favor a pointed nib with a bowl, shaped like an upside-down water drop. We mixed the paint with water to the desired consistency and dilution, forming a puddle on the palette. We loaded the nib with a brush before applying practice lines to a scrap of the paper being used. When the paint is not flowing from the nib as desired, a tiny bit of Synthetic Ox Gall can be added to the mixture. The additive may be mixed into the water used to dilute the paint, or a drop of the additive can be placed on the palette and a brush used to lift a tiny bit of it to add to the diluted paint.

Wet-in-wet applications:

Image 9: Water was brushed onto the black paper, then diluted paint was brushed on the wet paper. The first stroke created the central vertical line, then a horizontal brush stroke moved along the top and bottom edges of the rectangle and was joined by short vertical brush strokes on the sides at the corners. Paper was kept flat and not moved until the paint dried. Paints shown: top row, Interference Violet, Interference Blue, Interference Green; bottom row, Iridescent Gold, Iridescent Pearl, Iridescent Silver.

When diluted and applied to wet paper, these paints will move in the active and intriguing ways shown by many other QoR watercolors. Slightly damp paper, shiny wet paper, and puddles of water on paper will all call forth different behaviors. This can be seen in Image 9. The paper was placed on a flat surface and a rectangular area brushed over with water. As the paper bowed slightly up in the center from the water, water moved to the edges. The differences in wetness on the paper created different levels and types of paint movement. There is greater paint movement and color diffusion where puddles formed.

These special paints offer new and exciting possibilities, and shout or whisper in your paintings depending on how they are used. We encourage you to experiment with the one you find most interesting, and see where the adventures in shimmers might take your artwork.

Information about GOLDEN and Williamsburg Interference and Iridescent paints may be found through the reference links below: