Canal lock keepers still seal leaky gates with steam-railway coal ash

BBC Yorkshire reported in April 2026 that 'ashing up', a sealing method dating to the 19th century, lives on across West Yorkshire: when heavy boat traffic made water scarce, lock keepers floated coal ash from nearby steam railways on the water's surface overnight, and it was drawn into gaps in the oak lock gates, forming a bung.

The Canal & River Trust now collects ash from heritage steam railways — the Keighley & Worth Valley Railway, the Embsay & Bolton Abbey Railway and, most recently, the Middleton Railway in Leeds — storing it at Dobson Locks in Apperley Bridge. Team leader Darren Trolley, who has decades of experience with the technique on the Leeds & Liverpool Canal, calls it a simple, cost-effective solution: 'We pour a small amount of ash into the canal just above a lock, and the flow of water draws it into the gaps in the gates, forming a completely watertight seal.'

The trust tested rubber and polymer sealants, soaked sawdust, wood chips and natural clay over the years, and says none matched railway ash's reliability. The technique protected the canal's water supply during the previous summer's drought. Middleton Railway vice-president Ian Smith called it a win-win: the railway disposes of its ash responsibly while the trust keeps the locks working.

Ash is a byproduct the heritage railways must dispose of responsibly anyway — the sealing material costs nothing.

The seal self-targets: only the leaks draw ash in, so it packs exactly where water escapes.

Modern alternatives never matched it in testing, so a 19th-century trick beat engineered sealants on reliability.

The best fix can be another system's waste — a byproduct whose physical properties do the work no engineered product matched.

The partnership continues across West Yorkshire's heritage railways and the Leeds & Liverpool Canal, with the ash stored at Dobson Locks; the technique protected canal water supplies during the 2025 drought.