Intro to Soldering

This is essentially a class handout, but the information is a good overview and introduction to basic modern soldering. My tool list is a little tongue in cheek. Essentially, you will absolutely definitely want some of the tools in the "More Tools..." list. Your actual project and interests will dictate which ones. Also, I'm positive that I'm missing tools and chemicals that you may want. These are just the ones that are most common. This guide is meant to be the starting point, not the be-all end-all. Finally, I want to note that this is heavily, heavily skewed toward soldering silver, and soldering jewelry.

Tool List:

Basic necessities for soldering:

Clean metal pieces to be soldered together
Solder
Flux
Pickle solution (in a container)
Neutralizer (in a container)
Copper tweezers
Stainless steel tweezers
Torch
Soldering surface (charcoal, ceramic, etc.)
Small paintbrush for the flux

More tools you may want:
A jewelry saw and blades
Bench pin
Third hand with tweezers
Wire cutters
Round nose pliers
Stepped barrel pliers
Chain nose pliers
Steel ring mandrel
Steel bracelet mandrel
Tripod
Small steel anvil
Nylon, plastic, or rawhide hammer
Steel hammer (ball peen or chasing work nicely)
Solder pick
Files
Different grades of sandpaper (200, 400, 800, 1000, 2000, 3000)
Polishing compound
Rags
Nylon bristle brushes 

Brass brush
Dremel or flex shaft
Magnifier

You can find all tools necessary (and then some) at riogrande.com or ottofrei.com. Some of the above tools can be found at Harbor Freight, Lowe’s, Home Depot, or other hardware stores. Some tools may be found at hobby or specialty stores, but the average Joann’s, Michael’s, or Hobby Lobby is going to only be a good source for things like pliers and cutters.

What is SILVER SOLDER?

• Silver solder is silver that’s been alloyed with copper and zinc to lower its melting point. It comes in Hard, Medium, Easy, and Extra-Easy. Hard has the most silver content and the highest melting point, while Extra-Easy not only has the least silver content, it’s also got a bit of tin, and the lowest melting point. Professional jewelers do not use Extra-Easy. When performing multiple soldering operations, it can be helpful to use hard for the first step, medium for the second step, and easy for the third step. That makes it less likely that you will melt or disrupt an earlier joint when doing later work.

What is FLUX?

• Flux is a liquid or paste that keeps the metal surface from oxidizing during the heating process. If the metal oxidizes, the solder will not flow properly, and the joint will either not be made at all, or will be made badly. There are many different kinds of flux, as well as period recipes for flux. Personally, I use a borax cone and distilled water in an unglazed ceramic dish. Borax was known and used in metalwork in the medieval period. Because it’s more liquid than paste flux, it’s also easy to see if your surface is clean enough. The borax/water will bead up on the surface if it’s still dirty or oily.

What is PICKLE?

• Pickle is an acidic water solution that is used to clean the excess flux and oxidation from your piece after you’ve soldered it. Alum is a safe pickle (that’s made in using edible pickles, too!) that you can find in the grocery store, near the spices. Citric acid is another pickling agent that is environmentally friendly, and relatively safe to handle. I use sodium bisulfate. It’s a dry powder chemical I purchase from Rio Grande. Either way, your pickle solution will work better warmed. It can be in a glass jar on a candle warmer, or in a mini crockpot on low. It can also be used at room temperature, it may just take longer. If you are using sodium bisulfate, you MUST use copper tweezers, and do NOT touch the liquid with your hands. It can be irritating to the skin. Exercise caution when using chemicals and fire. There are other chemical pickling agents on the market, but these are commonly found.

What is a NEUTRALIZER?

• If you’re using sodium bisulfate, your piece must be neutralized before you can handle it. Simple baking soda will neutralize it. Create a separate solution of baking soda and distilled water and keep that near your soldering station. This liquid can also be used for quenching. Even if you’re using alum or citric acid, I would still recommend rinsing the piece in clean distilled water before moving on with it.

Soldering Basics:

Silver solder comes in several forms:

Wire - looks like regular metal wire, and should be labeled immediately. Can be cut to desired lengths with wire cutters. I find it helps to go over the end with some fine grit sandpaper just before cutting.

Sheet - looks like metal sheet and should be labeled immediately. The idea with sheet is to cut a little fringe at the end, and then cut pieces off the fringe as needed. You can also go over the end with some fine grit sandpaper before cutting the fringe.

Pallions - Pre-cut solder chips. These can be as small as .5mm x 1mm

Paste - Solder filings and paste flux pre-mixed together in a squeeze tube. You do not need to use a separate flux for this. Paste is favored by some who do filigree.

Metals being soldered must be CLEAN. Free of dirt, debris, and oil, including oils transferred from skin. A bit of fine sandpaper over the joint cleans it nicely. Alternately, dip it in your pickle solution for a minute, then neutralize, only touching it with tweezers.

Metals being soldered together must TOUCH each other. They must have good, contacting surface area. The solder won’t fill gaps. A lot of period examples of open filigree from the Byzantines feature granules at joints. My theory is that these granules provide surface area and contact between elements, ensuring a good join is made.

Silver solder will join brass, copper, mild steel, and stainless steel, as well as silver. It will also join any of these metals to each other. Gold solder should be used for working on gold, though easy silver solder can be used to join silver and gold together.

The pieces you’re joining together must both be at the same temperature, the temperature required to melt and flow the solder, in order for the solder to flow. The heat doesn’t directly melt the solder, the metal does. And the solder gets pulled toward the hottest thing. Joining a tiny piece of metal to a more massive piece of metal, therefore, is a bit tricky. It takes longer to heat up the bigger piece, and you risk melting the smaller piece. Sweat soldering can be a useful technique for this kind of task, and is something I’ll go more in depth about in a separate post. However, it's also what the tripod is for. When soldering a bezel to a back plate, or sometimes filigree or granulation to a back plate, where the pieces on top are smaller and lighter than your base, you elevate the piece and apply heat to the bottom. You heat the back plate first, and the heat transfers up to the smaller, more delicate pieces, so they heat more evenly.