Bath Bomb Colorant FAQ

Most bath bomb color comes from mica, dyes, lakes, or glitter, either mixed straight into the dry bath bomb mixture or dispersed into the oil portion of the recipe first. Since bath bombs dissolve into water, the colorant also needs to disperse evenly in water rather than just sit on the surface or clump, which is where an emulsifier like polysorbate 80 usually comes in. For how much mica to use, see the bath bomb section of How To Use Our Micas.

No. Bath bombs sit in bathwater that comes into contact with mucous membranes, so a mica's coloring agent has to be FDA-approved for general use, not just external use, the same approval level required for lipstick. Several common soap-safe micas, including most chromium-oxide-green and ultramarine-blue shades, aren't approved for this and shouldn't be used in bath bombs even though they're perfectly fine in soap. See Colors for Bath Bombs on our blog for the full breakdown of which colors are and aren't approved.

Polysorbate 80 is an emulsifier that helps oil-based ingredients, like mica or fragrance oil, disperse evenly into water instead of floating on top or clumping together. Without it, a mica-colored bath bomb tends to leave color and oil floating on the surface or streaked in the tub rather than dispersed through the water. Mixing your mica or oil-soluble colorant with polysorbate 80 before adding it to your bath bomb mixture, sometimes called "blooming" the color, helps it disperse smoothly and rinse away cleanly.

A common starting ratio is roughly equal parts polysorbate 80 to your mica or oil-soluble colorant, mixed into a smooth paste before adding it to your dry ingredients, though the right amount can vary depending on how concentrated the color is and how strong you want the tint. Start on the lighter side and adjust up in small increments, since it's easier to add more than to fix an overly saturated batch. For a full visual walkthrough of the blooming process, see our How to Bloom Dyes for Bath Bombs guide.

You can, but it comes with the same drawbacks as using it in soap, and then some. Food coloring is a water-based dye, so in a bath bomb it dissolves quickly and fully into the bathwater, which means it's more likely to noticeably tint skin and stain the tub than a colorant made specifically for bath products. It also isn't tested or approved for this kind of use. Colorants made for bath bombs are chosen and dosed specifically to minimize staining while still giving good color.

They can, especially with strongly saturated dyes and lakes, or with any water-based dye like food coloring. Using a lighter hand with colorant, choosing colors specifically labeled for bath bomb use, and rinsing the tub soon after your bath all help minimize staining. If you do end up with a stain, a paste of baking soda and a little water, or a standard bathroom cleaner, usually lifts it without much trouble.

Yes. Mica is a mineral-based option that adds color without synthetic dye, and some makers use approved natural colorants or very light mica dustings for a softer, more subtle tint. Keep in mind "natural" doesn't automatically mean "approved for bath bomb use," the same FDA approval rules apply regardless of whether a colorant is mineral-based or synthetic, so still check that any color you choose is rated for general use before adding it.

Both are FDA-certified colorants, but dyes are water-soluble and dissolve directly into the bathwater for a fully colored, translucent tint, while lakes are the same dye precipitated onto an insoluble base, which makes them oil-dispersible and better suited for solid-color streaks, swirls, or speckled effects that don't fully dissolve into the water. Our Bath Bomb Dyes and Bath Bomb Lakes sets are chosen and tested specifically for bath bomb use.