Natural resin that is dark yellow in colour and smells like Vanilla. It has been occasionally used (melted in alcohol) as a plastifier for alcohol varnishes since the 16th Century.
note: De Mayerne Theodor Turquet, Pittura scultura e delle arti minori. 1620-1646, a cura di Simona Rinaldi, Anzio, De Rubeis 1995.