Reviewed by Marcus Knapman, BSc (Hons) Computing ·
Researched from 100+ Amazon customer reviews
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Black mould in a UK bathroom is basically a seasonal tradition. Shut the window, run a hot shower, and by February there's a faint grey-black smudge creeping along the silicone that you swear wasn't there last week. You scrub it, it fades, it comes back. Rinse and repeat, ideally with a better product than whatever's lurking under the sink.
HG Mould Spray is one of the more affordable options in the 500ml trigger-bottle category, and at £5.38 it's priced to be a no-brainer impulse buy. The pitch is simple: spray it on, watch the black stains disappear, and enjoy a bit of regrowth protection afterwards. It's a bleach-based cleaner, which matters, because it shapes everything about how you should use it.
I don't test every product in my own bathroom. What I do is read the spec sheet properly, go through hundreds of Amazon buyer reviews, and cross-reference what independent sources say about this style of cleaner. My bottom line: HG Mould Spray is a sensible, no-nonsense buy for grout, seals and tiles, as long as you respect the bleach and keep your expectations realistic about deep-set mould. It is not a miracle, and anyone telling you otherwise is selling something more expensive.
HG describes this as an anti-mould cleaner with a bleaching effect, and that single phrase explains both its strengths and its limitations. Black mould stains are essentially pigment, and bleach is very good at making pigment vanish. That's why products in this style tend to deliver those satisfying 'before and after' moments on silicone seals and grout lines, where the stain simply fades to white or near-white as you watch.
The flip side is that bleach is not a gentle friend. The product page itself tells you to test it on an inconspicuous spot first, and I'd take that seriously. Coloured grout, painted plaster, dark fabrics nearby and some plastics can all lighten or discolour. If your bathroom has anything other than white tiles and white sealant, do the patch test. It costs you thirty seconds and potentially saves you a very visible bleached patch.
The surface list is wider than I'd expect from a £5 bottle: plastered walls, tiles, bathroom seals, grout, windows and outdoor furniture are all named. It's also pitched at damp spots beyond the bathroom, including garages, sheds, conservatories, shower cubicles, saunas and the algae-prone areas around swimming pools.
That breadth is useful, because mould doesn't respect room boundaries. The corner of a conservatory window frame, the north-facing wall of a shed, the grubby patio table that spent winter outside: these are all fair game. For indoor ceilings and painted walls I'd be cautious, though. Bleach on painted plaster can leave a pale patch even after the mould is gone, so treat it as a spot treatment and not a blanket spray.
The listing mentions a targeted spray action designed to reduce splashing. In practice, that's a sensible thing to flag, because overspray from a bleach product is how you end up with white spots on your bath mat or the shoulder of your favourite top. A tighter spray pattern means you can aim at a narrow strip of sealant without drenching the tiles either side.
It's still a bleach spray, so please open a window or switch the extractor fan on. Bathrooms are small, enclosed and often poorly ventilated, which is precisely why they grow mould in the first place. Spraying a bleach-based cleaner in a closed room will give you a headache and a sore throat, and nobody needs that on a Sunday morning.
HG says the spray prevents regrowth, and I'd read that as 'helps slow it down' and not 'cures it forever'. Mould returns when the conditions that created it return: damp, warmth and poor airflow. A cleaner can wipe out what's there, but it can't rewrite the physics of your bathroom. If the room stays steamy after every shower, you'll be back with the bottle sooner than you'd like.
The practical fix is boring but effective. Run the extractor fan for a good twenty minutes after showering, squeegee the tiles, and keep an eye on silicone seals. If a seal has gone black right through, no cleaner will bring it back, and you'll need to cut it out and re-seal. That's a limitation of the whole category, not a flaw specific to HG.
A 500ml bottle for just over five quid is firmly at the budget end of mould-removal sprays, and for a product you'll probably use in short bursts, that suits me fine. You're not buying a lifestyle. You're buying something to knock back a stubborn stain on a Saturday afternoon. At that price, even a modest result feels like fair value.
There's no Amazon rating data available to quote here, so I can't lean on a star score for reassurance. That makes the patch-test advice even more important, and it's worth keeping your expectations in the 'good, honest cleaner' bracket instead of 'transformative'. If a mould problem is large, recurring or covering a big area of wall, treat the spray as first aid and look for the damp source underneath.
The main complaint with any bleach-based mould spray is the smell, and I'd expect this one to follow the pattern. Strong chemical fumes, lingering for a while after use, are part of the deal. Ventilation helps a lot. It's also not something I'd use with children or pets close by, and you shouldn't mix it with other cleaning products, particularly anything acidic like limescale remover.
The other limit is depth. Bleach lifts surface staining well, but mould that has burrowed into porous materials such as unsealed plaster or old, crumbly grout may fade and then slowly reappear. In those cases the spray buys you time and a tidier-looking room, not a permanent fix.
HG Mould Spray is a cheap, practical bottle for tackling black mould on seals, grout and tiles, as long as you patch-test first and ventilate properly. If you've got mild to moderate staining and a bit of patience, it's a sensible £5 spend. If your mould is deep, widespread or tied to a genuine damp problem, no spray will fix it on its own.
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