Gilding on glass: New evidence from a 17th century flask found in Portugal

Lead was detected in the gilded areas suggesting that a lead based mordant was used in the gilding process to promote the adhesion of the gold leaf to the glass during the low temperature reheating of the object. The gold leaf composition was determined by LA-ICP-MS, and it was possible to ascertain its purity: between 22 and 23 gold carats.