I am trying to use up my small pieces of stained glass. I am in the process of doing a 6 panel window using small stained glass pieces using a mosaic method. The glue I bought said you need to let it set for 2 min. before you apply it to the surface. Some of my pieces are very small and this is very time consuming. I am using Carpenter's Goop [glue says it is waterproof and glues to glass]. Do you think I could spread the whole glass panel with glue and then put down pieces? That would mean some areas would spaces with no glass. Would this give me problems when I go to grout the window? Do you know of a glue to use for outside use that is waterproof and will work on glass and not yellow? I'd appreciate any guidance from you in this matter.Thank you.