The madder lake
The extraction procedure
Madder root (Rubia tinctorum) has been known and used for dyeing purposes since the 1st Century AD, and it is still one of the most appreciated natural dyes for violin making and in fine arts.
The lacquer is extracted by wasching the powdered root in cold water, and then the etching bath is prepared, consisting in boiling the root to extract the dyeing principle (alizarin). Thanks to the metal salts employed, the final colours obtained range between scarlet red (alum and zinc) to reddish-brown (iron) and purple brown (copper).
The precipitant solution usually comprises potassium hydroxide or carbonate and after adding the filtered etching water, it forms the lacquer, deposited on the bottom by decantation. After reiterated washes, the lacquered is ready to be filtered, dried and then ground.
In oil violin varnishing, madder pigments create nuances with a great intensity, brightness and transparency.