Silver soldering or “Hard Soldering” is an art form but it’s an art form that anyone can learn with a little practice. With silver soldering, practice really does make perfect. I perfected the art of silver soldering many years ago while working for a company that remanufactured refrigerators, deep freezers and air conditioners. I hadn’t really thought about the steps involved in the process for years. Silver soldering had become a reflex action for me. At least I hadn’t thought about them until my neighbor’s thirteen year old son started hanging out in my shop, watching my every move, eager to learn everything that I could teach him. Which brings me to the point that I want to make here, any knowledge that isn’t shared is wasted knowledge?
In order to silver solder you will need the following tools and supplies.
1) A BernzOmatic torch with a self ignition torch head
2) BenzOmatic 4 in 1 tubing brush
3) Stay Clean paste flux
4) Safety Silv 40 Flux Coated 1/6” O.D. X 18” Silver solder rods
5) Tube deburring tool
6) Tubing cutter, 1/8” to 1 1/8”
7) ¼” to 5/8” swaging tool set
8) Mini, close quarter tubing cutter, 1/8” to 5/8”
9) Emery cloth plumbers tape
All these tools and supplies are available from RSD Refrigeration Supplies Distributor online or from a local air conditioning and refrigeration parts and supplies outlet.
You will also need to pick up a few pieces of copper pipe of assorted sizes with a few fittings for each size pipe for practice. The following is a good choice
1) One 8 foot length of ½” rigid copper pipe
2) One 8 foot length of ¾” rigid copper pipe
3) One ½” coupling. and two ½” tees
4) One ¾” coupling and two ¾” tees
Plumber’s grade pipe and fittings will suffice for practice because it’s a great deal cheaper then A/C grade copper tubing.
Learning to silver solder isn’t difficult but it does take a little practice to become proficient at it.
How to silver solder like a pro
1) Begin by cutting each length of copper pipe into eight pieces of approximate equal lengths. It’s important to use a tubing cutter when cutting copper tubing because the slight compression made by the tubing cutter makes getting a proper fit much easier. Don’t force the cutter. Hand tighten the cutter until the cutting wheel digs firmly into the cutter. Then rotate the cutter completely around the tubing several times until the tubing is well scored. After that tighten the cutter’s feed know one turn with each revolution of the cutter until you have cut all the way through the tubing.
2) Using the deburring tool, carefully remove any burs from the inside of the pipe/tubing. This is very important when working with refrigeration because the slightest bur will disrupt the flow of refrigerants causing the system to become noisy and inefficient.
3) Now, using the 4 in 1 BenzOmatic brush, clean the inside of each of the copper fittings and the outside of each piece of copper tubing that you are about to join with silver solder. Clean the pipe back far enough so the cleaned areas extend a good ¾” to 1” beyond the end of the fittings.
4) Dry fit all the pieces to make sure they fit properly. The pipe should fit snugly within the fittings.
5) One fitting at a time, coat the inside of the fitting and the outside of the pipe with Stay Clean paste flux.
6) To begin soldering place the blue inner flame of the torch against the fitting. Move the flame evenly over and around the fitting. Watching the inner flame on the side of the fitting away from the torch you will be ready to silver solder when this inner flame turns green.
7) With the flame concentrated on the central part of the fitting apply the silver solder rod to the pipe where it meets the fitting. The silver solder should flow easily into the joint and around the pipe. If it doesn’t the pipe isn’t hot enough yet.
8) Once the silver solder has flowed inside the joint and around the pipe, remove the torch and wrap the pipe in a wet rag. This not only cools the joint quickly, it will provide you with a shiny, professional appearing joint.
9) Keep practicing until you have used all the fitting and lengths of pipe that you have prepared for practice. Remember practice makes perfect.
You may have noticed that we didn’t use some of the tools I listed. Not to worry, you will if you when you apply your new skills to real life projects.
