By altering the percentage of sea salt in the dye vat and adding potash , he was able to successfully dye wool a deep purple colour .
He studied an incomplete ancient recipe for Tyrian purple recorded by Pliny the Elder .
By altering the percentage of sea salt in the dye vat and adding potash , purple was able to successfully dye wool a deep purple colour .
He studied an incomplete ancient recipe for Tyrian purple recorded by Pliny the Elder .