Dyeing Seashells with Blackberry Juice

Seashells can be dyed by soaking in blackberry juice. The shells below were soaked in crushed blackberries for about a half hour. Shells that have abraded surfaces tend to turn bluish. I interpret this as the exposed aragonite (calcium carbonate) having a surface with a basic pH and turning the anthocyanins in the juice blue. Some shell surfaces that are not abraded and still have a sort of a "skin" can turn reddish. I interpret this as the anthocyanins remaining at a more acidic pH as they soak into this "skin".

LEFT: Undyed shells. RIGHT: Dyed shells.