HXTAL is a museum-quality epoxy adhesive intended for laminating, bonding, and repairing glass. This clear adhesive hardens when dry to produce the same index of refraction as glass, making it an ideal material for replacement pieces. HXTAL’s extreme versatility allows the substance to be thinned down to a clear coating or, in this case, thickened in molds to recreate missing glass elements. Window conservator Joannie Bottkol first made plaster casts of the spaces left behind from lost glass pieces in each window, before producing molds based off of them using a silicone putty. These silicone molds were then used to cast replacement panels out of HXTAL NYL-1. The conservator carefully colored each piece with Orasol dyes (transparent, lightfast, solvent-soluble dyes used in epoxy coatings and repairs) until she achieved the closest approximate color match for each piece. Can you spot the replacement glass in this window?