Restoring an old church window or for that matter restoring old windows can be a challenge. One of the important things that we try to do is use the existing glass instead of replacing broken glass with new glass, unless the glass is missing large pieces. Below is a couple of pictures showing the first part of using existing glass. Its a large puzzle that has no picture to look at and somehow you have to figure out where it all goes. After its all together the steps we follow are clean the glass, tape the glass together, glue the glass or I guess because its two parts we epoxy the glass together. The cure time on this epoxy is several days to a week. During that time it sits off to the side taped together as we take care of the rest of the window.