Chandelier arms are the center of a good chandelier. They are what adds the diameter and scale to the central body of the fixture. There can be many or just a few. We sell arms from 6-inches wide to a massive 24-inches wide. Occasionally these arms break and cause significant problems to the chandelier owner. We get asked from time to time about how to get the metal piece off the end of an arm.
First, the metal piece on the end of an arm is called a "ferrule". They come in brass (gold) or chrome (silver) colors. One end has a lip which is used to hold the bobesche in place. The bottom end does not have a lip which is the end that connects to the chandelier. For the most part chandelier arms have a "wireway" for the electrical wire to run thru them. (Occasionally on older fixtures wires can be placed on top or below the arms).
IMPORTANT: Make sure power is off to the fixture prior to doing any work on a chandelier.
There are a variety of reasons you might need to get the ferrule off an arm. So here's a sure fire way. There may be easier ways that involve stronger chemicals, but I'd used this method and it works without harsh chemicals or acid. I use regular baking soda and water to soften the plaster of paris that holds the crystal arm in the ferrule. Use lots of baking soda and soak, soak, soak. I use a mixture of about 3 to 1, water to baking soda or 3 cups water to one cup baking soda. Then I let the arm soak for a good 4 hours. Over time the plaster softens and you can chisel it out with a file or very thin screwdriver. I will warn you the paster of paris does not "dissolve" but it "softens" to almost a hard toothpaste.
The trick seems to be to take the loosest plaster off the top then resoak. Usually there is one side that is quite a bit thicker than the other and easier to get a tool in to take the plaster out. So you take some out, resoak and try again to get more out. Depending on the age of the plaster and the amount will determine how many times you need to repeat. The goal is to get enough plaster of paris out of one side the arm will loosen and fairly easily come out of the ferrule. You'll then need to clean out the residual plaster in the ferrule if your going to reuse the ferrule. Because ferrules are so cheap most of the time it's not the ferrule you are trying to save but rather the arm. You need to exercise caution when using the tool in chipping out the old plaster and even more caution when handling long arms. Don't apply pressure or try to force the arm out. The baking soda method works, but you need to be patient to allow it to work and soften the plaster.
I've seen people on-line try to give advise by using different kinds of acids and a host of other crazy things. I don't like harsh chemicals and the baking soda is something I always have on hand. It works.
I had a client who bought a long arm chandelier on-line. There were 30 arms that were 18-inches long. The fixture was about 42-inches in diameter and 5-feet tall. The weight of the arms with all the prisms eventually caused the ferrule to have some metal fatigue and start to bend down because of the weight of the prism side of the arm. It actually created a "fulcrum" effect with the outside weight pushing down on the edge of the ferrule. This caused the inside edge of the ferrule to raise up, lowering the prism side of the arm. Eventually several of the arms pulled out and hung by the electrical wire. In this case the arms were black glass and the only way to save the fixture would be to replace the dented ferrules and perhaps use stronger and longer threaded rod to hold the arms in. It appeared the original builder use lighter weight aluminum ferrules. A contributing factor was the owner replaced some small prisms with 40-mm balls which were considerably heavier than the original prisms.