Golden Acrylic Iridescent Acrylics - 2 oz tubes

• General Product Description
• Using Iridescents and Interference in Artwork
• Health and Safety

General Product Description

What are Iridescent and Interference Pigments

Iridescents are most familiar for their luster quality. All GOLDEN Iridescent Colors produce a luster quality by themselves, with other colors, or mixed with mediums. The GOLDEN line of Iridescents can be separated into 3 groups based on chemical composition.

Group I: All Interference Colors, Iridescent Pearl and Silver are in the first group. These colors are derived from mica platelets (the mica consists of an aluminum silicate, which has a crystalline structure that permits easy cleavage into very thin platelets). They are then coated with an extremely thin layer of titanium dioxide. Refraction (the change in direction of a light ray passing from one medium to another of different density) and reflection of light at the titanium dioxide layers, produce various colors and pearlescent effects.

Group II: Iridescent Gold, Copper and Copper Light make up the second group. These colors are derived from mica platelets, but an iron oxide coating is present either in place of, or in combination with, a titanium dioxide coating. The iron oxide coating results in pigments which possess hues as well as pearlescent qualities.

Group III: A third group consists of reflective colorants that do not fit the above descriptions.

• Highly reflective metallic pigments include: Stainless Steel (Coarse & Fine)
• Micaceous Iron Oxide: an oxidized form of iron, that is reflective as a result of the lamellar particle shape
• Mica Flakes: naturally-occurring mica particles mined from veins in the earth, in which the color is determined by mineral differences only nature can control.

GOLDEN "Coarse" Iridescent/Interference colors are simply larger particle size versions of our "Fine" Iridescent/Interference products. Colors available in the Coarse Iridescent line include Copper, Copper Light, Gold and Pearl. The Interference colors available are Blue, Gold, Green and Red.

Luster Arises from Layers of Pigments.

The pigments in the first two groups (non-metallics) are composed of very thin, highly reflective and transparent platelets. The plate-like shape allows the pigments to be easily oriented into parallel layers within the transparent medium. When viewed, a portion of the incident light will be reflected by the uppermost layer of pigments, while the remainder of the light will be transmitted and subsequently reflected by lower layers. It is this multiple reflection of light from many microscopic layers that produces the observed shimmering luster or pearlescent effect.

Light Interference.

A second property is at work in the Interference mediums. The phenomenon is light interference, which is most familiar to us in the rainbow effect created by a thin layer of oil on the surface of water. This phenomenon was identified by Thomas Young in 1801 in a series of investigations that were eventually instrumental in advancing the theory for the wave-like nature of light.

Whenever light strikes a boundary between two materials of different densities, the light will be either reflected or refracted (hence, transmitted). If the refracted light encounters another boundary between materials of different densities, this light will again either be reflected or refracted. This process continues every time a new phase is encountered.

Light interference results from these concurrent multiple reflections and refractions of light. If the interference is constructive in nature, the light waves reflected from the different layers will be "in phase" and a strong color stimulus results. With Interference colors, a specific thickness of the titanium dioxide layer (TiO2) layer allows only a narrow band of wavelengths of light (representing a certain color) to be reflected in phase, while all other reflected wavelengths of light (colors) undergo destructive interference and are not observed. As these pigments are transparent, a portion of the light will be transmitted and the resulting color will appear as the compliment to the reflected color.

Excellent Weathering Resistance.

In general, mica is quite insoluble in fairly strong acids or bases, and is not affected by water. The micas are also inherently lightfast, and when combined with a 100% acrylic medium, yields paints that are very stable, offering excellent permanency.

These chemical and UV resistance properties distinguish the Iridescent Mediums from most metal pigments, such as coppers, bronzes and even aluminum flakes. Metals are well known for their ability to rust or corrode, as they continually oxidize over time. With the Iridescent colors, all components are already in the most stable state of oxidation, and there is NO possibility for change resulting from further oxidizing reactions.

The metals that GOLDEN has chose to offer are known to demonstrate remarkable durability. Our Stainless Steel (Coarse & Fine), which consists of extremely durable 316L grade stainless, are very resistant to salt spray and acid spotting, as well as alkaline cleaners or detergents. The Micaceous Iron Oxide, while being highly reflective, is actually not in a metallic state, but is already oxidized.

Using Iridescents and Interference in Artwork

Maintaining Bright Surfaces: The Options.

The highly reflective surfaces of the flake pigments used to produce Iridescent Mediums are extremely thin. These platelet pigments range from 1 to 2 microns in thickness, and up to 90 microns in diameter for the Fine and 180 microns for the Coarse. Consider that the surface of an average flake of Iridescent Pearl could carry over 50,000 Carbon Black pigment particles placed side by side. This larger particle size, coupled with the transparent nature of mica, yields a certain weakness in color strength.

Although no rule is absolute, some procedures for maintaining bright surfaces have proven their effectiveness. What follows is a brief review of some of the more successful approaches.

• To maintain the brightest possible effects with Iridescent Colors, avoid mixing them with opaque colors. Similarly, matte mediums and matte gels will also reduce iridescent qualities by scattering the light that hits the surface.
• With Interference Mediums it's helpful to keep in mind that the phenomenon of light interference produces a unique color "flip" in these paints. An Interference paint reflects one color and transmits its complement. For example, in intense direct light, Interference Blue will reflect a lustrous bright blue color, while indirect light results in the appearance of the complement - in this case, a buff. This color "flip" is unique and varies according to the surface on which it's applied. On a darker surface, Interference Colors tend to have a much stronger primary color, while not showing the complement. To produce the brightest colors with the Interference line, add a small amount of black - 1:100 or less. The black will strengthen the reflected color. Add more black if darker colors are required.
• Be aware that blends made with matte materials tend to reduce the luster of Interference mediums, adding gloss materials, such as GOLDEN Gloss Gel, increase interference qualities by increasing reflectivity. The addition of the Gloss Gels/Mediums also provides better spacing between pigment particles, thus maximizing the effectiveness of each reflective pigment.
• Overall, thicker applications will cloud the paint and weaken the intensity of the Interference Colors. Thinner applications increase the interference qualities. As the level of dilution increases, the pasty look disappears. Applying thin layers, whether by wash or glaze, effectively forces particles to lay flat with the large broad side facing the viewer. As more particle surfaces are exposed, the shimmer or luster increases.

  As the Iridescent and Interference colors are relatively transparent, it is important to consider the impact of the base coat. By effectively varying the color of the base coat, the overall color effect can be varied dramatically, especially when the Iridescent or Interference layer is applied to maximize its transparency. For example, Interference Blue can be applied in glaze form over a light yellow or a dark red to yield some unique color effects.

  Similarly, other relatively transparent colors can be wet blended into the Iridescent or Interference colors to achieve some interesting effects. Combining both additional colors and Gloss Gels/Mediums can create some exciting effects for glazes, in thin or thick films.

  This information should provide initial understanding of Iridescent and Interference Mediums. The important point is not to stop at face value. They can be as useful to a palette as white and can provide a range of colors and effects never before available.

Health and Safety

This product carries the Art & Craft Materials Institute, Inc. AP Seal. This indicates that the product was certified in a program of toxicological evaluation by a medical expert to contain no material in sufficient quantities to be toxic or injurious to humans or to cause acute or chronic health problems. Product conforms to ASTM D4236. All Golden products should be used in accordance with safe handling practices.