Consumer advocacy teardown
Hagesan Black Spot Remover alternative & active ingredient dupe
Stop paying £24.99 for HG. The bulk active is Sodium hypochlorite 14–15% (industrial / dairy grade) — 64% less per working litre than a typical pack.
- Active
- Sodium hypochlorite
- CAS
- 7681-52-9
- Dupe
- Sodium hypochlorite 14–15% (industrial / dairy grade)
- Saving
- 64% / L
Saving is per litre of working-strength mix versus a typical pack price, not versus the DIY kit total. Shop prices move — always check the listing.
The Marketing Claim & The Catch
A typical 5 litres pack of HG Hagesan Black Spot Remover is about £24.99 in patio & exterior. That is a snapshot, not a live Amazon price — listings, sizes and deals move. The marketing line is that you are buying a finished lifestyle product, not a weighed chemical.
On the pack: Dissolves deep-rooted black lichen dots; Restores natural sandstone, slate and granite; and Visible results in 2 hours.
The catch: Standard commercial bleach solution sold at five times agricultural merchant prices.
- “Dissolves deep-rooted black lichen dots”
- “Restores natural sandstone, slate and granite”
- “Visible results in 2 hours”
Proprietary Blend & Dosage Breakdown
The labelled active is Sodium hypochlorite at 9.5%. Everything else in the pack is water and surfactants.
At 9.5% active, most of what you pay for is carrier and packaging. The brand is selling convenience, fragrance and a label — not a uniquely potent molecule.
Branded working strength is whatever comes out of the bottle. The bulk alternative is 15% Sodium hypochlorite 14–15% (industrial / dairy grade), mixed to 1:1 with water (yields ~7.5% working solution) + 10 ml washing-up liquid.
- Labelled active
- Sodium hypochlorite
- 9.5%
- Carrier
- Water and surfactants
- Retail pack
- 5 litres · £24.99
The Active Chemical Alternative (Dupe Stack)
The dupe stack is Sodium hypochlorite 14–15% (industrial / dairy grade) at 15% bulk. Indexed as CAS 7681-52-9, formula NaOCl. Buy it as 5 litres for about £18.00 from Amazon UK.
Working strength: 1:1 with water (yields ~7.5% working solution) + 10 ml washing-up liquid. Indicative cost £1.80 per diluted litre — 64% below a typical branded pack on a per-litre basis, before you reuse leftover bulk.
Follow the mixing method and the supplier SDS. Wear the listed PPE. Do not mix incompatible oxidisers, acids or ammonia.
- Apply onto completely dry paving using a chemical-resistant pump sprayer or plastic watering can.
- Allow 30–60 minutes dwell time without letting the surface dry out entirely.
- Rinse thoroughly with copious fresh water. Keep run-off away from delicate grass edges.
- Never mix with acids, vinegar or ammonia.
Mixing desk
Dilution calculator
Switch between filling a sprayer and covering a measured surface. Figures are educational estimates from the listed ratio — always check the SDS.
Formula
Sodium hypochlorite 14–15% (industrial / dairy grade)
- Concentrate
- 2,500 ml
- millilitres of liquid
- Water
- 2.5 L
- carrier volume
- Batch cost
- £9.00
- 5 L working solution
- Saved vs retail
- £15.99
- 64% · retail £24.99
Estimated coverage at the listed rate: 25 m².
Side-by-Side Price & Potency Comparison
Head-to-head comparison
| Measure | Retail brandedHG | Raw active dupeDupeStack |
|---|---|---|
| Product | Hagesan Black Spot RemoverAmazon UK search — listing, not a confirmed seller | Sodium hypochlorite 14–15% (industrial / dairy grade) |
| Pack / unit | 5 litres · £24.99 | 5 litres · £18.00 |
| Active | Sodium hypochlorite at 9.5%Carrier: Water and surfactants | 15% bulkNaOCl |
| CAS number | Not disclosed on pack | 7681-52-9 |
| Working strength | Ready-to-use pack | Dilute 1:1 with water (yields ~7.5% working solution) + 10 ml washing-up liquid |
| Cost per litre | £5.00 / L typical pack | £1.80 / L mixed from bulk |
| Headline saving | Baseline | 64% cheaper |
| COSHH / PPE | Follow the branded SDS | Gloves. Chemical-resistant gloves (nitrile or neoprene)Eye protection. Indirect-vent splash goggles — not ordinary spectaclesRespirator. Rated respirator for dusts or vapours as specified on the SDSVentilation. Use outdoors or with mechanical extraction |
Active ingredient and cheaper alternative — FAQ
What is the active ingredient in HG?
HG Hagesan Black Spot Remover is labelled as Sodium hypochlorite at 9.5%. The carrier is Water and surfactants. Pack size: 5 litres. The bulk equivalent we index is Sodium hypochlorite 14–15% (industrial / dairy grade) (CAS 7681-52-9).
Is Sodium hypochlorite 14–15% (industrial / dairy grade) safe on paving?
Used at the listed working strength (1:1 with water (yields ~7.5% working solution) + 10 ml washing-up liquid), the dupe is the same chemistry as the branded pack for paving, porcelain and masonry. That is not a blanket all-clear: read the supplier SDS, wear the listed PPE, keep acids away from hypochlorite, and follow UK HSE/COSHH rules. Wellness teardowns are supplements, not medicines.
Is there a cheaper alternative to HG Hagesan Black Spot Remover?
Yes. The bulk equivalent is Sodium hypochlorite 14–15% (industrial / dairy grade) (CAS 7681-52-9). Indicative saving 64% per working litre versus a typical £24.99 pack. Working strength: 1:1 with water (yields ~7.5% working solution) + 10 ml washing-up liquid. Live shop prices move.
How do you mix the Hagesan Black Spot Remover dupe stack?
Apply onto completely dry paving using a chemical-resistant pump sprayer or plastic watering can. Allow 30–60 minutes dwell time without letting the surface dry out entirely. Rinse thoroughly with copious fresh water. Keep run-off away from delicate grass edges. Never mix with acids, vinegar or ammonia.
DupeStack provides chemical concentration data and educational mixing guides. Always review official manufacturer Safety Data Sheets (SDS) and comply with UK Health and Safety Executive (HSE) and COSHH regulations when handling concentrated substances. Some links on this site are affiliate links.
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DIY stack · 64% / L vs branded
£38.50indicative kit · Amazon cannot add a mixed search kit as one basket