Fascinated to read in New Scientist about a masonry paint developed by Rachel Armstrong of University College London (UCL) that could make limewashing obsolete and turn buildings into carbon sinks.

Apparently Rachel has dissolved salts and esters in oil to create a paint that, once applied, absorbs carbon dioxide from the atmosphere to transform the coating into calcium carbonate – limestone.

In spite of many limestones used in construction being millions of years old, new limestone is being created in shallow tropical seas all the time – some even contains CocaCola bottle 'fossils'. 'Growing' limestone on to ancient carvings is being used as a way of restoring them. And at least since the days of Henry VIII the petrifying properties of the well at Mother Shipton's cave in Yorkshire have been amusing visitors by turning pieces of clothing, twigs and even the remains of small dead animals into stone in a few hours or days. In hard water areas, where the hard water is caused by dissolved calcium carbonate in the water, kettles are 'furred' with it.

Rachel says the product she has developed, named 'biolime', will provide extra strength and insulation to buildings, as well as helping them to achieve carbon neutrality.

Her latest plan, being presented at UCL's Bartlett School of Architecture next month (February), is to use an underwater version of the material to create a limestone shelf under Venice to stop it sinking any further.