Why won't the black stain come out of my shower silicone?

If you've killed the mould, scrubbed the seal, tried every spray — and the silicone is still grey or black — you haven't done anything wrong. Once mould has grown into old silicone for long enough, the black pigment stains the material itself. At that point the mould can be dead and the seam can still look discoloured. Knowing that saves you a lot of pointless scrubbing.

Why does silicone stain when tiles don't?

Because silicone is soft, slightly porous, and permanently wet at the base of a shower. Glazed tile is hard and sealed, so mould sits on top and wipes away. Silicone is a flexible sealant that absorbs moisture and holds it against the wall — the perfect long-term home for mould. Given weeks or months, the mould's pigment (melanin) works its way into the silicone's surface layer, the way red wine stains a benchtop rather than beading on it. Kill the living mould and you've solved the health and recurrence problem, but the colour that's already soaked into the material doesn't lift, because it's no longer a surface deposit — it's part of the silicone now. This is normal, and it's why old shower seals look tired even after a deep clean.

Is the stain still dangerous if the mould is dead?

A dead, killed colony is far less of an issue than active, spore-producing mould — the concern with mould is the living, growing colony. Once the mould is killed at the root, it's no longer establishing new growth or shedding spores from that spot the way active mould does. What's left in stained silicone is discolouration, not a thriving colony. That's a genuinely better position to be in, even if it's not the spotless-white result the ads promise. Health authorities link exposure to active indoor mould with respiratory symptoms, so removing the living mould is the meaningful step; the cosmetic stain in the silicone is a separate, lesser matter. This isn't medical advice — if anyone has ongoing symptoms, see a GP.

Won't stronger bleach get the colour out?

Bleach can lighten the pigment temporarily, but it doesn't remove it and it doesn't solve the real problem. Chlorine bleach fades the black by attacking the colour, which is why a fresh bleach makes old silicone look better for a while — then the grey creeps back as the bleach's effect wears off and any surviving roots regrow. You're treating the symptom (colour) and skipping the cause (living mould in a wet, porous seal). We won't pretend our spray restores stained silicone to white either — that would be the same overpromise in a natural bottle. Clove oil's job is different and honest: eugenol, its main compound, is a documented natural antifungal that disrupts fungal cell membranes (Pinto et al., 2009, Journal of Medical Microbiology). It kills the mould so it stops coming back. The colour that's soaked in is cosmetic.

So what's actually worth doing?

Kill the mould, keep it from returning, and replace silicone only when the look genuinely bothers you. Spray the Clove & Eucalyptus Mould Spray lightly over the seal, leave it about 20 minutes, and wipe — its five ingredients are water, castile soap, methylated spirits to dry the surface, 100% pure eucalyptus oil and 100% pure clove oil, with no chlorine. Repeat weekly as light maintenance so new mould never establishes. If a seam is badly stained and you want it white again, the honest fix is to cut out the old silicone and re-caulk — a $15 job — then keep the fresh bead mould-free with a weekly spray so you never have to do it again. That's the difference between chasing colour and solving the problem.

We've been making cleaning products in Australia since 1895, five generations on. Part of a 130-year reputation is telling you when a product can't do something — stained old silicone is one of those times, and we'd rather say so than sell you a miracle. A verified reviewer in Melbourne valued exactly that honesty: "Very effective, easy to use. Follow the directions and to date the mould has not resurfaced."

Frequently asked questions

Why is my shower silicone still black after cleaning?

Mould pigment soaks into old, porous silicone over time. Once it's absorbed, killing the mould won't lift the colour — the stain is now part of the material.

Does the Clove & Eucalyptus Mould Spray remove silicone stains?

No. It kills the mould at the root so it stops returning, but it does not remove staining that has penetrated old silicone. For a white finish, re-caulk and then maintain.

Is stained silicone still a health risk once the mould is dead?

The concern is active, growing mould. Once it's killed, what remains is discolouration rather than a thriving colony. See a GP about any ongoing symptoms — this isn't medical advice.

Should I just replace the silicone?

If the look bothers you, cutting out and re-caulking is the only real way to get white back. Keep the new bead mould-free with a light weekly spray.

The stain isn't a sign you failed — it's a sign the mould was there a long time. Kill it, keep it gone, and re-caulk only if you want the cosmetics. Read next: why mould keeps coming back in shower silicone, does clove oil actually kill mould at the root, and how to get rid of black mould in grout and silicone for good. Or see the Clove & Eucalyptus Mould Spray.

Reference: Pinto, E. et al. (2009), Journal of Medical Microbiology, 58, 1454–1462.