The Saturday Morning Home Repair Blog (SMHRB) is where we gather to discuss the many and varied aspects of home repair. Some here are trained professionals. Some, talented DIYers. Some, hopeless thumb-hammerers. All are welcome. Please feel encouraged to ask questions, share successes, lament sags, drips and cracks and, as always, share any advice that you have for the rest of us.
Soldering is something most any homeowner can do. Today I will provide you with the basic knowledge to accomplish a solder joint that will out live you.
First, let’s talk some safety…
Safety glasses and gloves are a must for me, it is not much fun to get a drop of hot molten solder in your eye, trust me.
Fire extinguisher… well, duh, normally when soldering the water will be shut-off, not a good time to start a fire.
Spray bottle… when soldering near wood, especially old wood I spray the wood with water and allow it to soak in and spray again. If soldering against construction paper or something like plastic covered ducting, stick a piece of scrap sheetrock between it and the pipe. You can burn against a piece of sheetrock and it barely gets warm on the other side.
Always clean the pipe with sand cloth (made for cleaning copper pipes and found at all hardware stores) until it’s shiny. If the fittings are new I might not bother cleaning them, but it’s not a bad idea to give yourself the best chance at a successful solder joint. I’ve never seen a leak caused by a pipe or fitting being too clean. Fittings can be cleaned with a fitting brush or sand cloth.
Now that the joint is fit-up and fluxed it is time to solder. But first remember these important rules: don’t burn yourself and don’t place yourself under the joint to be soldered unless you want hot flux and solder dripping on you. Pipe and torch tips will remain hot for a while after removing the heat.
Before I let you light up the torch, I’m going to tell you about solder and the basics of how it works. Many people will tell you that the heat draws the solder, but that’s not true. Capillary action is what makes it work, the physical attraction of the two materials and the closeness of the two surfaces just draws it right up. Of course the solder has to be in the right state or phase. The most important part of soldering is getting it there, after that nature takes over. Solder has three phases: solidest, pasty and liquidest. The pasty range is where we want to be; it has become liquid, but not watery. Different solders have different pasty ranges. While I was an apprentice, the move to lead-free solders started and there was a lot of fear because the only option at the time was 95-5 (95% tin-5% antimony) with a very narrow pasty range at a high temperature. It was much more difficult to use than 50-50 (50% lead-50% tin). The solder I use now is Silvabrite 100; lead-free, a wide pasty range for easier use and 0.4% silver which adheres well to copper. Can’t help but see it as analogous to where we are in our push to stop climate change, when needed humans came up with a solder; stronger, easier to use and safer. Progress…not as scary as some people think.
Almost ready to squeeze the striker, but first we should discuss what kind of torch and fuel to use. For most jobs I use a hand-held MAPP tank with a “Turbo” tip. Some torches come with an integral igniter, but the igniters are prone to failure and they lack the swivel tip that is easier to use in tight areas. Propane can be used in lieu of MAPP, it does not burn as hot but still provides more than enough heat. If I have large amounts of joints to solder I pull out the acetylene tank or “B” tank, not something most homeowners have or need. Oxy-Acetylene torches are not used for soft-solder joints, too hot.
Finally…lets get soldering. We learned above that heat does not draw the solder, what we want is a nice even heat. You want to use the area approximately 2 or 3 inches from the tip of the blue cone. Heat rises so always start on the bottom with the torch and solder. Always keep the torch moving, either back and forth while heating or drawing back the flame while feeding the solder. Warm the pipe first; then move to the fitting and check occasionally with the solder until it starts to melt into the joint. Draw back the torch and begin feeding the solder working from the bottom to the top on each side. Once full it will start dripping off. Remove all heat and feed a little more solder until it stops taking it. After it solidifies you can wipe with a moist rag to clean off excessive flux.
Last couple tips: turn the water on slowly to avoid disturbing any sediment, after pressurizing the line remove the aerators from the faucets and flush out debris.