1. AkzoNobel Performance Coatings, Color ResearchRijksstraatweg 31, Sassenheim AJ2171 The Netherlands
2. Movable Heritage Knowledge Sectorthe Netherlands Cultural Heritage Agency (RCE)Hobbemastraat 22, Amsterdam ZC1071 The Netherlands
3. Van Gogh MuseumPaulus Potterstraat 7, Amsterdam AJ1070 The Netherlands
4. Department of ChemistryUniversity of AntwerpUniversiteitsplein 1, WilrijkB‐2610 Belgium
5. National Gallery of Art4th and Constitution Avenue NW, Washington DC20565