Astonish Mould & Mildew Remover Spray 750ml
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Verdict
If you have a black-mould issue around the bath sealant or shower grout, this is the cheap UK answer that works.
Pros
- Genuinely shifts black mould from silicone sealant and grout
- Cheaper than HG equivalents
- Results visible within an hour
- UK-made
Cons
- Contains sodium hypochlorite, bleach smell, ventilate well
- Will stain coloured fabrics
- Not a daily product
Full review
Astonish Mould & Mildew Remover is the £3.50 fix for the bathroom problem most UK households learn to ignore, black mould around bath sealant, shower grout, window frames, and behind taps. The cheaper alternative to HG Mould Remover, and just as effective for the typical UK case.
The active ingredient is sodium hypochlorite (bleach), at a concentration that’s effective on visible mould without being strong enough to damage standard bathroom sealants. You spray on the affected area, leave for 30–60 minutes (depending on severity), then rinse. Black mould visibly recedes within the contact time and fully clears with a second application if the patch is older.
It’s the only product in this guide that we’d specifically warn about. Sodium hypochlorite + acid (i.e. spraying this and then immediately spraying Viakal nearby) produces chlorine gas, small amounts in a ventilated bathroom aren’t dangerous, but they’re avoidable. Use Astonish on its own, rinse thoroughly, ventilate, and only then move on to other products.
Don’t use on coloured fabric (shower curtains, bath mats), it bleaches. Don’t use without ventilation. Don’t use on clothing you’d like to keep.
The 750ml bottle is large for a specialist product and lasts most UK households 1–2 years. Subscribe & Save isn’t enabled, buy once, use as needed.
An alternative worth mentioning: HG Mould Remover Foam Spray. Slightly stronger formula at roughly twice the price. Worth the upgrade only if Astonish hasn’t shifted a particularly entrenched patch.
Why mould keeps coming back: ventilation. After you’ve removed it, improve airflow. Open windows after showering, run the extractor fan, leave the bathroom door open. Re-treating every 2–3 months is normal in a poorly-ventilated UK bathroom, even with regular cleaning.
Buy this if: you have visible black mould in the bathroom, and a working extractor fan or window.
Skip this if: you have no mould problems (don’t buy preventatively, it doesn’t work that way).
For the full ranking of how this product compares with the alternatives, see our guide to the best bathroom cleaner.
