Some 37 years ago, Mario Modestini, Chief Restorer of the Samuel H. Kress Collection, set out to adapt modern synthetic resins for use in retouching. In collaboration with the National Gallery of Art in Washington, DC, a testing project was carried out and polyvinyl acetate (AYAB) was chosen, because its low glass transition temperature promised longevity of the restorations. In addition, PVA could be dissolved in alcohol or acetone, some of the least harmful solvents for the health of conservators. A description of the technique is documented by photographs from the studios of both Mario Modestini and the present author.