Updated: Jun 2, 2020
It's not always easy to tell if a pigment will be ok to use in your resin artwork. However, when deciding what I'm going to use in a piece, there is just one thing that will tell me if it is ok to use or not. Is the pigment archival? I want all my pieces to look as good 20 years from now as they do the day I create them. So for me, there is really only one question. Will it stand the test of time?
So what is archival pigment and how can you tell if your pigment is?
What kind of color you use in a given application and its outcome will be determined by the basic structure of the epoxy polymer you are using. Even similar polymers, produced by different companies or in different regions of the world, can vary in composition and therefore respond to colorants differently. A particular color that works well in an epoxy produced in North America, for instance, may yield a totally different result if it is used in material sourced in Europe or Asia. The molecular structure of the polymer determines its processing characteristics, which in turn will influence color outcomes.
Inks/dyes vs Pigment: What's the difference?
Inks/dyes are soluble and disperse in resin polymers on a molecular level. (like sugar in hot water) Pigments on the other hand are insoluble solids that must be dispersed in the polymer by mixing.
Inks make it easier to achieve bright, clear, transparent colors and are the best solution for coloring transparent resins. Pigments being solids, are better for deep, saturated, opaque colors.
Archivability refers to the durability and longevity of an ink or pigment and is determined by three factors: water-resistance/waterproof, pH-neutral/acid-free, and lightfastness. Lightfastness refers to how well the ink or pigment holds up to light exposure. The light source does not make a difference. Fluorescent and halogen lights are very damaging to inks, but the most damaging is direct sunlight. Incandescent lights are less damaging to ink and artworks in general, which is why they are traditionally used in galleries. LED lights are the least damaging.
Acrylic ink, India ink, mica, and pigment powder is the most lightfast, and dyes are the most sensitive.
Acrylic ink is derived from liquid plastic, which allows for the pigments to layout flat when the solvents evaporate. One of the benefits of acrylic ink is that the color and the plastic are molecularly bonded, which makes its lightfastness rating the highest of all inks. Acrylic ink is waterproof, archival, pH-neutral/acid-free, and has the longest lifespan of all inks. It sticks to a wide range of surfaces, and with the exception of some whites, all colors are very opaque.
India ink was actually first created in China and is also known as China Ink. Originally available only in black, it now comes in other colors. India ink has historically been made with carbon and contains varnish or shellac, which gives it permanency and makes it waterproof. Most India ink has a sheen to it, which is amplified on a smooth surface
Mica and pigment powders-
Light, heat and weather resistant; acid and alkali resistant. Non-conductive. Stable chemical properties with easy dispersing performance.
For mica, the colorful effects depend on different metal oxides coated on the surface of the mica flake substrate. Benefits from strict tests in the production process usually ensure the quality and stability of products. Micas come in various particle sizes and one of the largest selections of colors.
Pigment Powder looks like ground-up colored chalk. Pigments are names that are usually based on their actual colors, for instance, ultramarine blue, turquoise, cadmium red, titanium white, etc.
Pigment powder products come in many forms once binders are added, and is what most resin pigment pastes are made from. Unlike mica powder, they do not shimmer. They are great for coloring things (that’s their job!).
Craft paint- contains too many water-based binders and will fade over time.
Alcohol ink- is dye-based – kinda like Kool-Aid cordial. Pigments are dissolved in Isopropyl (or Ethyl) alcohol and a binder; the granules become small and translucent. Very beautiful, but not always stable when exposed to light.
Dye-based ink - is created with water-soluble dyes combined with gum arabic or other vehicles to create wide color range and brilliance. Although this ink can be stunningly bright, it has a low lightfast rating, so it should stay away from prolonged light exposure and stay within sketchbooks and portfolios.
Other Pigment NOT suitable to resin work
Acrylic paint is usually mixed with water, color pigments and various binding agents. It is also mixed with additives such as preservatives, depending on the product variant and brand. The water and additives in these paints can lead to absolutely unpredictable and also undesirable results when combined with epoxy resin. In addition, when using acrylic paint, the surface of the castings is often matt and streaked.
Oil paints usually contain lipids, which make it impossible to mix the paint with the resin properly. Rather, the experiment would immediately lead to the formation of lumps which cannot be mixed.
Watercolors are also not really suitable for use in combination with epoxy resin. However, the reason here is not that the colors would not bond with the casting resin. Rather, they are simply much too weakly pigmented.
Find info and tips like this and more in my Beginners Resin course. a 35 page PDF with accompanying video guides! www.mermaidtrash.com