Silicone sealant
The flexible bead round a bath or a worktop, and the most common place a household meets mould it cannot remove — because the growth is inside the material.
In detail
Silicone sealant is a flexible cured polymer used to close the joint between two surfaces that move relative to each other. It is chemically robust — unaffected by ordinary detergents, acids and alkalis at domestic strength — and its practical problem is biological rather than chemical. Sealant in a shower or around a bath is permanently damp, slightly textured, and often carries a film of soap and skin oils, which is an ideal growth surface. Once mould has established, the visible black marking is the surface expression of growth that has penetrated the bead, so a bleach-based product removes the colour and leaves the organism, and the marks return within weeks in the same places. The environmental regulator's guidance is consistent about the general principle: correct the moisture problem or growth returns, and porous materials that have been colonised may need to be discarded rather than cleaned. For sealant that translates directly: a bead that keeps regrowing is a bead to cut out and replace, which is cheaper and more permanent than repeated treatment. Sealant also fails mechanically, and a joint that has parted from one face is admitting water behind it.
Properties
Sensitivity
- Acids
- Not known
- Alkalis
- Not known
- Chlorine bleach
- Not known
- Heat
- Not applicable
- Abrasion
- Recorded
- Porous
- Recorded
“Not known” means CleaningHQ has not established this, not that the material is unaffected.
Why
- Silicone sealant is explained by Moisture control and recurrence
- Silicone sealant is explained by Biofilm
- Silicone sealant is explained by Cleanability is designed in
A sealant bead is the junction two surfaces could not make cleanable, filled in.
Related
- Silicone sealant is commonly affected by Mould
- Silicone sealant is commonly affected by Mildew
- Silicone sealant is commonly affected by Soap scum
- Silicone sealant is commonly affected by Mould fungi
- Silicone sealant is commonly affected by Fungal spores
Hacks and claims involving this
- Borax for mould Unresolved
- Killing the mould solves the problem Does not work
Sources for this page
Sources
United States Environmental Protection Agency (EPA) · Government or regulator
Relied on for: That the moisture problem must be corrected or mould returns, and that porous materials which have been colonised may need to be discarded rather than cleaned. (states this directly)
Verification: a person has read the passage relied on.
Read on — The 'Mold Cleanup' section and the 'Tips and Techniques' list. Supports a narrower statement — our claim was reduced. CleaningHQ had been prepared to attribute a bleach position to the EPA in either direction, which the page does not support. The catalogue now states only what the agency states — detergent and water, dry completely, fix the moisture — and the widespread belief that mould requires bleach is handled as an assessed claim resting on the absence of any authority recommending it, not as an EPA prohibition.
Last reviewed by a person on .