When finishing soldering on a suncatcher, coat the edges with flux, tin the upper edge with solder, repeat on the other side, then flux and tin the outer flat edges, with 60/40 solder. Then hold the suncatcher with a pair of pliers, in a vertical position, and begin to apply the solder in small amounts along the top edge, moving the piece around so the top edge that is level changes. Then go back and connect the little blobs with more solder.
Building up the edge of suncatchers helps the foil from being ripped off accidentally, or just peeling back on its own from being damaged during the cleaning process. This will also allow you to bury a length of fine wire (20 gauge or 22 gauge) around the outer edge of the suncatcher. This provides reinforcement, especially if the suncatcher has a design that has a part of it sticking out on its own, unsupported by the main body of the piece.