Lining
GCL brands compared: NAUE, CETCO, Solmax, Geosyn and Wrekin
Bentofix, Bentomat, BentoLiner — the names on a GCL specification vary more than the products do. Here's who makes what, and what actually matters when you choose one.
A geosynthetic clay liner — GCL — is a layer of sodium bentonite clay held between two geotextiles. When the bentonite hydrates under a cover layer it swells into a barrier of very low permeability, and it seals small punctures on its own. The principle is the same whoever makes it, but the products differ in how the clay is held, how much of it there is, and what they're built to resist.
We install GCLs from all of the manufacturers below, to the specification or on our recommendation. This is a contractor's view of the field, not a buying guide from any one of them.
The main manufacturers
- NAUE (Bentofix) — the German manufacturer's needle-punched GCL range, with variants for ponds and nature reserves, for landfill and mining, and with a bonded coating for slope sealing.
- CETCO (Bentomat) — one of the longest-established GCL names, with a range that includes products for chemically aggressive contents as well as standard water containment.
- Solmax (GSE BentoLiner) — Solmax took on GSE's geosynthetics range, and BentoLiner is its GCL line, often specified alongside its geomembranes.
- Geosyn — a UK geosynthetics supplier whose range includes GCL alongside HDPE and LLDPE membranes and protection geotextiles.
- Wrekin (GCL 4500) — a UK-supplied needle-punched GCL with granular bentonite between a woven and a non-woven geotextile, sold for SuDS ponds, lagoons and containment.
What actually separates them
| Question | Why it matters |
|---|---|
| How much bentonite per m²? | More clay generally means a more forgiving barrier and better self-sealing. |
| Powder or granular bentonite? | It affects how evenly the clay sits and how the laps are sealed. |
| Needle-punched or stitched? | Needle-punching locks the layers together, so the GCL resists peeling and holds on slopes. |
| What will it hold? | Clean water is easy. Slurry, leachate or salty water can stop bentonite swelling, so chemistry decides the product. |
| Coated or uncoated? | A bonded membrane coating adds a barrier and helps where hydration or slopes are a concern. |
What matters more than the badge
A GCL fails for the same reasons whoever made it: it's laid on a poor formation, the overlaps aren't sealed, or it hydrates before it's confined. The formation has to be smooth and free of sharp stone; every lap and detail needs bentonite paste or granules; and the cover layer has to go on promptly after the GCL is laid, because bentonite that swells without confinement just washes away.
On our jobs we check the formation, deploy and seal the panels, detail the pipes and edges, and hand over with the records and the cover depth needed. The contractor then places the cover and hydrates the GCL. Get those steps right and any of these products will do the job it was specified for.
GCL or membrane?
A GCL gives a natural clay bed and simple detailing, but it needs confinement and the right water chemistry. Steep slopes, exposed edges or aggressive contents usually point to a welded membrane instead — or to a GCL used underneath one as a secondary barrier. Our pond liner guide covers that choice in more detail.
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