New coating should be rust-free for 25 years, bringing to a close Scotland’s never-ending paint job

For years it’s been a metaphor for a never-ending task but by Christmas the painters of the Forth Railway Bridge should be able to hang up their brushes for at least 25 years.

The bridge was the first in the world to be built entirely of steel, however it has needed constant maintenance since it was completed in 1890. So much so that the phrase ’like painting the Forth Bridge’ entered into common use.

However, since 2002 Balfour Beatty has been restoring the structure, shot blasting the 230,000m2 of steelwork back to bare metal before applying a new coating developed by Leigh Paints which is guaranteed to keep it rust free for 25 years.

The coating contains glass flakes, which for years has been used as protection for structural steelwork in aggressive environments but was considered uneconomic for bridges. However, the firm developed a lower cost system which has a lower dry film thickness. This overcame concerns that a thick film of epoxy glass flake may be unable to cope with the movement of the structure - it flexes as trains cross over it - and that it would crack, particularly around rivet heads.