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  • Eric_Byctt

Veggie-based Coating Used for Pond Liner


Many waterfront homes on the west coast of British Columbia enjoy creating beautiful gardens. This particular home has placed a concrete pond for ornamental fish or Japanese koi.

This case study concerns a small residential pond where the concrete needed a liner coating that wouldn’t kill the fish or leak. Most coatings are petroleum-based and need several layers like a primer. Base-coat and topcoat that off-gases and can affect aquatic life.


The client wanted a lining product that was as natural as possible with zero potential toxicity over the lifetime of the pond. They also wanted zero VOCs and low maintenance. Some pond liners and coatings deteriorate from UV at exposed areas. Some also become brittle and crack over time leading to leakage.


Castagra Ecodur is made from sustainably grown castor oil and naturally occurring soft rock gypsum. It is essentially a mineral hybrid vegetable oil urethane. This is permanently flexible, highly durable and chemically neutral. This is rated ANSI/NSF-61 by CSA for potable drinking water.

If by chance, the pond liner is damaged by a sharp object, Ecodur can be repaired throughout the lifetime as brand new Ecodur will bond onto its original Ecodur coating. It is also extremely durable against the effects of UV and saltwater tests have shown no measurable deterioration after over 20 years.


The new concrete pond was allowed to cure over a month. The surface was clean and dry. Ecodur has exceptional bonding and doesn’t require a primer. It has no maximum thickness and can be applied with one coating.

The coating was manually applied to a thickness averaging 30-40 mil, and the surfaces were tacky around 30 minutes. Full cure is achieved within 24 hours, allowing for the pond to be used. The pond’s integrity is reported to be 100% with no detectable leaks.

This coating application was performed by Rob Humphries at Blue Frog Spray Foam based in Gibsons, BC.

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