If you only remember one thing, remember this: the three resin colorants are not competitors, they are tools for three different jobs. Mica powder is a dry mineral shimmer pigment you stir into the batch for pearlescent depth. Alcohol ink is a transparent dye you drip onto the surface to trigger cellular and lacing “petri” effects. Resin dye is a concentrated liquid pigment that tints an entire pour evenly in either transparent or fully opaque color. Pick the one whose effect matches your project, dose it conservatively, and you will get a clean cure. The comparison table below lays the three side by side; the sections that follow explain why each behaves the way it does and which one to reach for per project.
How each colorant actually works
The reason these three look and behave so differently comes down to what is in the bottle and where it ends up in the resin.
Mica powder is finely milled mineral pigment, usually a synthetic mica platelet coated with metal oxides. Those flat platelets are what reflect light and create the shimmer or pearl sheen — no liquid colorant can fake that optical effect. Because mica is a solid you are suspending in the resin (not dissolving), it adds semi-opaque color and sparkle at the same time. The Let’s Resin 50-color set ships roughly 5 g per color and is cosmetic grade, so the same jars work for resin, soap, candles, and nail art.
Alcohol ink is a dye dissolved in alcohol. When you drip it onto freshly poured epoxy, the alcohol fights the resin’s surface tension and the dye migrates outward, drawing the open cells and lacy borders that define “petri” art. It is fundamentally a reactive surface colorant, not a batch tint. Jacquard Pinata inks ship in 0.5 fl oz (14.79 ml) bottles and conform to ASTM D4236 (the art-material safety labeling standard). One important nuance: the metallic Pinata colors are opaque and lightfast because they use real metal and mica pigment, while the regular dye colors do not.
Resin dye (liquid pigment) is a highly concentrated colorant formulated specifically for casting resins. Alumilite’s liquid dye comes in 1 fl oz (29.6 ml) bottles in both transparent and fully opaque variants — the opaque ones contain fillers that block light for a solid color. Because it disperses uniformly through the mixed resin, it is the only one of the three that reliably gives you the same color top to bottom in a deep pour.
Opacity and visual effect compared
This is where the choice usually gets made. Look at the comparison table above and you will see three distinct visual signatures:
- Mica lands in the middle — semi-opaque color with shimmer. It is what you want for a geode that catches the light or an ocean scene where the “water” needs depth and movement.
- Alcohol ink is transparent and luminous (except the metallics), which is exactly why it produces glowing, layered cells. It is the worst choice if you want a flat solid color, and the best choice if you want translucency and reaction.
- Resin dye gives you the cleanest control: dial in a transparent stained-glass look or a fully opaque solid, with no texture or sparkle muddying the color.
A practical consequence the specs do not show: mica’s shimmer can slightly mute raw color saturation, because the reflective platelets scatter light. If you need a punchy, fully saturated single hue, a transparent resin dye will read more vivid than the same color in mica.
Blending behavior and deep pours
How a colorant moves through the resin matters most when you are casting thick. Resin dye mixes into a uniform tint and stays put, which is why it is the default for deep pour river tables where you need consistent color through inches of resin. Mica is heavier than the resin and can slowly settle toward the bottom of a deep pour, leaving a gradient or a darker base — sometimes a happy accident for ocean art, sometimes a defect. For deep work, either keep the pour shallow per layer or accept (and design around) the settle. Alcohol ink is the opposite problem: it does not want to stay anywhere, it wants to spread and react, so it is a surface technique, not a body tint.
One handling note that trips up beginners: never dump mica in dry. It clumps. Disperse it into the resin (or pre-mix a small slurry) and stir thoroughly, scraping the cup walls, or you will find unmixed specks in the cured piece.
Dosage and cure safety — the numbers that matter
Every colorant has a ceiling, and crossing it is the single most common reason a “colored” pour stays soft or tacky. The hard limits, conservatively stated:
- Resin dye: stay under 6% of the total mixed resin + hardener by weight. Past that the curing chemistry is disrupted. Many makers cap themselves at 3% for safety. Because the dye is so concentrated, often less than one drop colors a small batch and roughly 1 oz can tint about 32 oz of resin — you almost never approach the ceiling by accident.
- Mica powder: dose 0.5-3% by weight; about 1/8 tsp (0.5 g) per 1 oz of resin gives near-opaque coverage. Above roughly 4% the resin can cloud and the cure can suffer.
- Alcohol ink: there is no clean percentage because it is applied to the surface, but the alcohol carrier itself can create soft spots if you flood too much in. Use it sparingly and let it react.
The reliable rule across all three: start with the smallest amount, mix, and build up. You can always add more pigment; you cannot un-tint a batch, and you cannot rescue a pour you over-pigmented past its cure limit.
A short safety note: resin colorants do not change the fact that uncured epoxy and its fumes warrant ventilation and a properly rated respirator during mixing and pouring — that is a resin-system concern, not a pigment one, and is covered in our broader equipment guidance. Mica is fine on skin once mixed, but as a fine dry powder it should not be inhaled — keep it out of the air when measuring.
Lightfastness and longevity
If the finished piece will sit in sunlight or near a window, this section decides for you. Mica is a mineral pigment and resin dye is engineered for casting, so both resist UV fading well. Alcohol ink is the weak link — its dye colors are fugitive, meaning they fade and can even visibly disappear under UV, with light shades like yellow and pink going first. This is not a small caveat: a vivid petri piece can lose its lightest colors within months on a sunny shelf. If you love the alcohol-ink look, pour it in a UV-stabilized resin and keep the piece out of direct sun, or lean on the opaque metallic inks, which hold up because they are pigment-based rather than dye-based.
Cost per pour
For budget, resin dye wins outright. Its extreme concentration means the per-pour cost is the lowest of the three even though a single bottle is not cheap. Mica is close behind on value because a large multi-color set spreads across dozens of projects. Alcohol ink is the priciest per pour — you use more of it, and as a surface effect it is not stretching across the whole batch the way a dye does. If you are pricing out a production run of coasters or jewelry, dye is the economical base coat and you spend ink only where the effect earns its keep.
Which colorant for which project
- Geodes and ocean/beach art: mica powder, for the shimmer and the believable depth of “water” and crystal.
- Petri art, cellular and lacing effects: alcohol ink — nothing else makes those cells.
- River tables and large casts: resin dye for an even, consistent tint through the depth; reach for transparent dye for a tinted-glass river or opaque for a solid color.
- Jewelry and small castings: dye for clean solids, mica for shimmer pieces, ink for tiny petri pendants (sealed against UV).
For thick river-table work specifically, pair your dye choice with a true casting resin and proper depth-per-layer limits — see our working, cure, and demold times reference so the color choice does not get blamed for a cure problem that was really a depth or temperature issue.
Mixing colorants together
The professional move is to layer them. Tint the base batch with resin dye or mica for an even background color, then drip alcohol ink on top for cellular accents. This gives you the best of both worlds: a controlled, lightfast field with reactive highlights. Two cautions only — keep your total colorant load under the 6% ceiling so the resin still cures, and remember that too much alcohol can leave soft spots. Used in moderation, the dye-base-plus-ink-accent combination is the most versatile technique in resin art.
The three recommended products compared
The three products in the comparison table above are chosen as the clean representative of each category, not as rivals: the Jacquard Pinata 36-color set for alcohol-ink effects, the Let’s Resin 50-color mica set for shimmer and broad palette, and the Alumilite liquid dye for even, cost-effective batch tinting. Their full pros, cons, and specs are laid out above. If you are building a first kit, the most useful starting trio is one opaque resin dye, one or two mica colors that match your aesthetic, and a small alcohol-ink set you treat as a special-effects tool rather than a daily tint.