Will this neon yellow show up on dark or unbleached hair?

This balm works by depositing direct pigment onto the hair instead of using ammonia to open and change the hair structure. Because the colour sits on and around the outer layer, the starting shade of your hair matters a lot. On very light or bleached hair the result can be bright and fluorescent. On darker hair the same pigment has less contrast to show against, so the tone often looks soft, muted, or may be barely noticeable except as a slight sheen.

For a true neon yellow, the most predictable base is a light or pre-lightened one. If your hair is medium brown or darker, you may need to lighten it first or accept a subtle tint. Porosity also affects the result: porous, previously processed hair can absorb pigment unevenly and may hold it longer than expected, which is why a small strand test is useful before applying the balm all over.

If you are not sure whether your base is light enough, take a small section underneath, apply a small amount, rinse it, and see what shade actually appears before committing to a full application.