Patio & exterior
Jenolite Rust Remover Gel dupe
Why pay around £8.99 for Jenolite? The bulk active is Phosphoric acid 81% (food / technical) diluted to ~25% — 78% less per working litre than a typical shelf pack.
From the retail pack to the active and the mix
1 · Retail
Jenolite Rust Remover Gel
500 millilitres · £8.99 typical snapshot
Water and a thickener
2 · Active
Phosphoric acid
25% on the label
7664-38-2H3PO4
Bulk Phosphoric acid 81% (food / technical) diluted to ~25%
3 · Mix
1:2.2 (to ~25% w/w working, matching the gel)
£3.90 per working litre · 78% less than the shelf pack
- Active
- Phosphoric acid
- CAS
- 7664-38-2
- Dupe
- Phosphoric acid 81% (food / technical) diluted to ~25%
- Saving
- 78% / 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.
Label teardown
What the pack promises versus what the label chemistry actually is.
The marketing claim
“Converts rust to a paintable phosphate film”
The chemical reality
This is not oxalic (that is HG masonry rust) and it is not hydrochloric (Mortar Clen). Phosphoric acid etches rust to iron phosphate. Technical 81% phosphoric diluted to about 25% is the same attack without the gel tax. Keep it off limestone.
Active vs filler
25% Phosphoric acid · 75% carrier / filler — Water and a thickener
- Typical retail
- £8.99
- 500 millilitres
- Estimated active cost
- £1.93
- Scaled from bulk £12.50 / 1 litre
- Indicative markup
- 4.7×
- Snapshot maths, not a live shop price
The Marketing Claim & The Catch
A 500 millilitres pack of Jenolite Rust Remover Gel typically retails around £8.99 in patio & exterior. That is a UK shelf-price snapshot for the maths on this page — not a live shop quote or a manufacturer RRP. Listings, sizes and deals move. The marketing line is that you are buying a finished lifestyle product, not a weighed chemical.
On the pack: Converts rust to a paintable phosphate film; and No sanding on light surface rust.
The catch: This is not oxalic (that is HG masonry rust) and it is not hydrochloric (Mortar Clen). Phosphoric acid etches rust to iron phosphate. Technical 81% phosphoric diluted to about 25% is the same attack without the gel tax. Keep it off limestone.
- “Converts rust to a paintable phosphate film”
- “No sanding on light surface rust”
Proprietary Blend & Dosage Breakdown
The labelled active is Phosphoric acid at 25%. Everything else in the pack is water and a thickener.
At 25% 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 81% Phosphoric acid 81% (food / technical) diluted to ~25%, mixed to 1:2.2 (to ~25% w/w working, matching the gel).
- Labelled active
- Phosphoric acid
- 25%
- Carrier
- Water and a thickener
- Retail pack
- 500 millilitres · £8.99
The Active Chemical Alternative (Dupe Stack)
The dupe stack is Phosphoric acid 81% (food / technical) diluted to ~25% at 81% bulk. Indexed as CAS 7664-38-2, formula H3PO4. Buy it as 1 litre for around £12.50 from Amazon UK.
Working strength: 1:2.2 (to ~25% w/w working, matching the gel). Indicative cost £3.90 per diluted litre — 78% 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.
- Causes burns. Splash goggles, household gloves, ventilation. Always add acid to water. Never mix with bleach.
- About 1 part 81% phosphoric + 2.2 parts water lands near 25% — the same order of strength as the branded gel.
- Apply to dry rusted steel, dwell 15–30 minutes, rinse, dry, prime. Not for aluminium, zinc, or marble.
- 1 litre of 81% makes about 3.2 litres of 25% liquor. Store in a labelled HDPE bottle.
Dilution recipe
0.5 L working batch
Working strength 1:2.2 (to ~25% w/w working, matching the gel). Educational estimate from the listed ratio — check the SDS before you mix.
Chemical
156 millilitres
Phosphoric acid 81% (food / technical) diluted to ~25%
Water
0.34 litres
Carrier / diluent
32% concentrate · 68% water by working volume (solids are dissolved into the water share).
Required PPE
Loading calculator…
Side-by-Side Price & Potency Comparison
Head-to-head comparison
| Measure | Retail brandedJenolite | Raw active dupeDupeStack |
|---|---|---|
| Product | Rust Remover GelAmazon UK search — listing, not a confirmed seller | Phosphoric acid 81% (food / technical) diluted to ~25% |
| Pack / unit | 500 millilitres · £8.99 | 1 litre · £12.50 |
| Active | Phosphoric acid at 25%Carrier: Water and a thickener | 81% bulkH3PO4 |
| CAS number | Not disclosed on pack | 7664-38-2 |
| Working strength | Ready-to-use pack | Dilute 1:2.2 (to ~25% w/w working, matching the gel) |
| Cost per litre | £17.98 / L typical pack | £3.90 / L mixed from bulk |
| Headline saving | Baseline | 78% cheaper |
| COSHH / PPE | Follow the branded SDS | Gloves. Chemical-resistant gloves (nitrile or neoprene)Eye protection. Indirect-vent splash goggles — not ordinary spectaclesVentilation. Use outdoors or with mechanical extractionAcid-resistant PPE. Apron and gloves rated for corrosive liquids |
Active ingredient and cheaper alternative — FAQ
What is the active ingredient in Jenolite?
Jenolite Rust Remover Gel is labelled as Phosphoric acid at 25%. The carrier is Water and a thickener. Pack size: 500 millilitres. The bulk equivalent we index is Phosphoric acid 81% (food / technical) diluted to ~25% (CAS 7664-38-2).
Is Phosphoric acid 81% (food / technical) diluted to ~25% safe on paving?
Used at the listed working strength (1:2.2 (to ~25% w/w working, matching the gel)), 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 Jenolite Rust Remover Gel?
Yes. The bulk equivalent is Phosphoric acid 81% (food / technical) diluted to ~25% (CAS 7664-38-2). Indicative saving 78% per working litre versus a pack that typically retails around £8.99. Working strength: 1:2.2 (to ~25% w/w working, matching the gel). Live shop prices move.
How do you mix the Rust Remover Gel dupe stack?
Causes burns. Splash goggles, household gloves, ventilation. Always add acid to water. Never mix with bleach. About 1 part 81% phosphoric + 2.2 parts water lands near 25% — the same order of strength as the branded gel. Apply to dry rusted steel, dwell 15–30 minutes, rinse, dry, prime. Not for aluminium, zinc, or marble. 1 litre of 81% makes about 3.2 litres of 25% liquor. Store in a labelled HDPE bottle.
DupeStack provides chemical concentration data and educational mixing guides only. Wellness pages compare food supplements, not medicines or prescribed treatments. Always review the supplier Safety Data Sheet (SDS) and comply with UK Health and Safety Executive (HSE) and COSHH regulations when handling concentrated substances. Mixing and storage are at your own risk. Some links are affiliate advertisements (Amazon Associates, eBay Partner Network, and Awin when those programmes are live). Commissions do not change listed concentrations or calculator output.
Related guides
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Citric, sulfamic, lactic, acetic, formic, oxalic and phosphoric for descaling and rust; how they differ from brick acid and caustic drain gel — with DupeStack teardown links.
Patio guide
Patio cleaners decoded: BAC, DDAC, bleach, acid and degreasers
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Patio guide
How much patio chemical do you need? Measure first
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- Retail pack
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- Retail pack
- £8.50500 millilitres
- Raw active
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£22.50Save 78% / L
Indicative DIY stack