Soldering stained glass can sometimes be frustrating for a beginner. Do not be discouraged; it may take a little while to get really good, but with a little practice and patience, anyone can be an expert. This article describes the best practices for soldering when using the copper foil method.
If you have never soldered stained glass before, it is going to be well worth the effort to practice on some scrap pieces of glass first. I recommend taking four square pieces, wrapping copper foil around the edges and assembling them into one large square. This type of arrangement has the two main types of joints, a single joint where two pieces of glass meet and an intersection joint, where multiple pieces of glass meet. The intersection joint is in the center of the large square where all four pieces of glass meet. This kind of joint can be the trickiest to get looking good. Keep reading, I will explain how to get that pesky joint looking great every time.
Once your soldering iron is hot and the glass assembled, the first step is to tack all the pieces together. Apply soldering flux on all the joints. I have found the easiest way to tack together stained glass is to hold the soldering iron with the flat part of the tip horizontal just above the glass, touch the solder to the iron tip until a small bead forms and lightly touch the copper foil. It does not take much sold to tack the glass pieces together. Start at the edges and work in towards the center making sure to tack every piece. You do not want them moving when doing the final soldering.
With all the glass tacked together, the second step is to solder all the joints. This is typically the hardest thing for a beginner to master. This is mainly because two things must be done at the same time, keeping the soldering iron moving and feeding the solder onto the iron. The key to an even solder line is to feed a consistent amount of solder as the iron is moved across the joint. Feeding too much solder creates large bulging solder joints and not feeding enough solder leads to flat uneven joints. Apply flux to all the joints. Start at the edge of a joint; hold the iron so the flat part of the tip is vertical to the work piece.
As you touch the solder to the iron tip, place it on the joint and begin dragging or pushing (while it is more comfortable) while maintaining a constant solder bead. When you come to an intersection where multiple joints meet, make sure to apply welded about one half inch into each incoming joint. If you do this correctly, all the solder at the intersection will be melted and cool at the same time. This makes that joint look very smooth. Start at another joint and work your way towards the intersection again. This time, when you reach the solder that is sticking out from the intersection, simply melt a little ways into it to join the new solder line with the old one. You should not have to re-sold the intersection again. Do not forget to wipe the tip of the iron frequently on a damp sponge to keep it clean.
One mistake that many beginners make is to pick the soldering iron straight up a joint. This will leave an imperfection in the solder which will have to be fixed later. Instead, move the iron back and forth on the joint so there is melted solder on either side of the tip. Pull the iron off to the side making sure to keep it touching the glass. Once free from the melted solder, you can pick up the iron. The flux will keep the solder from sticking to the glass and make for a very professional looking joint.
Do not get discouraged if, at first, the solder lines are not perfect. Simply drag the iron across the joint again until you get the results you were looking for. After a little practice, you will be soldering stained glass like a professional.