Here's a photo of the almost disconnected cap ..
A view of the lamp. As you can see, the small cap is being asked to support quite a bit of weight.
My first step was to remove the cap entirely. Then I melted out the old beads of solder around the edge.
Next I melted off as much of the old solder as I could. This is a good quality brass cap, which is a "heat sink", meaning that it draws a lot of heat out of the iron.
I asked my husband Eric to use his sanding drill bit to remove more of the old solder. Here the brass is clean and shiny, so it will adhere much better to the solder and the dome.
Many older lamps have un-grinded edges on the glass. This lamp was no exception. I took the time to use a hand file to smooth down the sharp glass. This makes the glass easier to handle and allows copper foil to bond more securely.
To give this cap added staying power, and to distribute the weight of the dome more evenly, I decided to add in three segments of flat braided reinforcement wire, shown here. To prepare it, I applied liquid flux to the flat wire, then added a thin film of solder to both sides. This process is called "tinning."
Then I attached the three strips of tinned reinforcement wire as shown. When I applied the soldering iron to the strips, they bonded with the fresh solder beads that I added earlier. Note that I also added new copper foil to the interior of the dome's opening.
Eric assisted me on this one, by soldering the outer edge of the cap to the dome. The solder dots fused with the brass and the copper foil for a good bond.
As seen from inside the dome, he melted the flat reinforcement wire into the solder lines of the dome, then extended them onto the interior of the brass cap. Then he melted on a generous amount of solder to assure that the three contact points will be firmly attached. This creates a very strong bond between the cap and the dome.
After the soldering was complete, I applied black patina to all of the solder, inside and outside the dome. After it dried, I applied stained glass finishing compound. This is a light wax which protects the patina.
And here is the repaired lamp. Thank you Geri, for entrusting your dad's lamp to my care. I hope you and your family will enjoy it for many years to come!