PMC Presents: Soldering Metal Clay Part 1- Torches by Lora Hart

Metal clay is a marvelous material. It’s been around for about 20 years and we’re still discovering new ways of working with it. It’s so good that sometimes artists think it’s all they need to use when creating and finishing their designs. Sometimes that may be true, but I learned a long time ago that it’s smart to use the tool that’s best for the job at hand. In the jewelry world, that may mean that a solder join is more durable than one made with clay, or that a attaching sterling earring post would be stronger and more appropriate than just firing a piece of fine silver wire in place.Soldering isn’t difficult. It’s like anything else that has a learning curve, you need to practice, make mistakes, have successes, devise your way of doing things, and then do it all again – as many times as is necessary. “Practice Makes Proficient” is a phrase I like to repeat, not only to my students but to myself as well.In terms of the longevity of your work, joins are usually the first to fail. Un-soldered jump rings actually move a bit as they are worn, so that the combination of friction and movement may cause them to open so the jewelry piece will be lost. Fine silver used as earring wire is very soft and will deform and potentially break if bent and straightened too many times (this is called ‘metal fatigue’). Sterling wire fired higher than about 1250ºF becomes brittle and breaks. Learning how to solder earring posts to the back of a stud, or closing the jump rings that attach a chain to the pendant or clasp will be invaluable. In no time at all you’ll move on to soldering a bezel closed, and then soldering that bezel to a backing plate.  All of which can be accomplished with a butane torch (depending on how large you’re working). This article will describe the basic tenets of soldering and some processes that I’ve developed which I hope will help your learning curve to straighten out a bit.

NOTE: All safety precautions presume that soldering is intermittent and of short duration. If you solder more than a few minutes at a time, you’ll need to do more research into proper safety and health guidelines.

THE SOLDER

There are basically two kinds of solder

  • Soft solder flows at temperatures under 850ºF. An alloy primarily made of copper, tin and lead, soft solder is best left to plumbing, circuit boards, and stained glass windows. Soft solders are not much better than epoxy because they only join the very surface of the material. I even found one article online that proudly described it as “metal glue”! In jewelry making, the color and consistency is also an issue. The lava-like flow of polished soft solder is unattractive and will never be a good color match to silver.
  • Hard solders flow at temperatures above 1200ºF. The specific alloy of silver solder varies between manufacturers, but is primarily a combination of silver and zinc. The ‘harder’ the solder, the more silver it contains, the better the color match. Hard solders work by capillary action, which means that little ‘roots’ flow into the ‘arteries’ in metal that are formed as it is heated. When the metal sections cool, the solder has created an internal bond and two sections of metal become one.

Hard solders come in their own hardness continuum. Extra easy flows at around 1200ºF, easy flows at 1325ºF, medium at 1360ºF and hard flows at 1450ºF. There’s also something called IT solder that flows at 1490º and is primarily used in enameling (enamel flows between 1300ºF and 1450ºF)

  • The liquidus (the temperature when solid metals become liquid) of fine silver is 1760ºF. Sterling’s is 1640ºF. But each metal starts to melt much earlier, and the core structure is compromised sooner than you might expect. Some metal clay artists have been thought to successfully fire sterling wire in place because it “still looks like wire” But the inner crystalline structure has started to change, has been weakened, and makers find that their sterling wire element snaps sooner or later. This happened to me once upon a long time ago, when a charm bracelet with sterling, fired-in-place, jump ring elements starting dropping all it’s baubles.

The general rule is that you want to use the hardest solder you can, depending how many soldering operations are going to be done on a single item. So for instance (in traditional metalsmithing) if you were going to solder a bezel to a backing piece, and attach a bail, you’re performing 3 operations. Use hard to close the bezel, medium to solder the bezel to the backing plate, and attach the bail with easy. But what if you also wanted to set a pearl on a peg, or attach pin findings to the back of the piece? You’re out of solder variations, right?

In reality, solder gets a little bit harder each time it is flowed. So you can safely use each level of hard solder at least three times (and sometimes more) before you need to move to the next level. I’d probably just use medium solder for every join in my previous example. You may never have to use hard solder on a project with only 4 solder joins. But you might WANT to. Why? Because hard solder has more silver in it and is a better color match. If you’re using patina, it may not be an issue.  If there’s a lot of texture in the piece, it’s probably not an issue either. But hard solder also creates the best solder join possible.

There are also a variety of solder types/shapes you can use.

  • Metal solder is sold as wire, sheet, and pre-cut pallions. Note: Metal solder looks like…metal! Be sure to mark it with Sharpie to differentiate it from sheet metal, and mark each grade to tell them apart. Something like black for hard, red for medium, and green for easy. Bend the ends of wire solder to mark them. One bend for easy, two bends for medium, three bends for hard.
  • I prefer paste solder, which is powdered solder blended with flux. Paste solder also comes in easy, medium, and hard. Loaded into a syringe (that’s familiar!), it’s designed to be used with a tiny, metal, syringe tip. Instead of the tip, I just extrude from the syringe, and pick up a small amount of paste solder with a toothpick and place where I need it. Remember to mark paste solder as well! I don’t use hard very often at all, so I don’t do anything but write “hard” with a black Sharpie on the label. I use yellow tape for medium, and masking tape with pink Sharpie for easy. I write the words ‘medium’ and ‘easy’, but still like to color code.  You can use whatever markers you have handy, but be consistent throughout your career.

FLUX

To use solder you also need to use something called flux.  Flux is primarily used to keep metal from oxidizing during the soldering process. There are many types of flux, that we don’t have time to get into in this article – but a few popular paste flux’s are “Handy”, “Batterns”, or “Dandix”.  Popular liquid flux’s are “Pripps” and “Cupronil”. One of the reasons why soldering on fine silver is so much easier – no oxidation! But you still need flux because the solder can oxidize too. So if you’re using metal solder, brush a little bit of flux at the join and on the actual solder pieces. If you’re using paste solder – it’s built in! No need for additional flux.

PICKLE

Pickle is used for two reasons – to remove oxidation, and to remove excess flux. If you’ve only soldered an earring post, or closed a jump ring – that amount of oxidation can be sanded away. No need for pickle in my opinion. But if you also have glassy, hardened flux – pickling it is much easier than trying to grind, sand, or otherwise file it away. If you’re soldering to fine silver – the base piece will have no oxidation. If you’re soldering to sterling silver, copper or bronze clay, chances are good that you can just use your regular methods of finishing. But if you have stubborn oxidation that isn’t coming off easily you’ll need to pickle.

There are a variety of ‘professional’, chemical, pickle solutions you can buy like PH Down from the pool supply or Sparex from a jewelry supply. I choose not to store chemicals in my studio, so I use one of a number of natural, food grade options instead. Are they as good? Depends on what you mean by good. Do they do the job? Yes. Do they work as fast? No. Will they work better if heated? Often, yes.

  • Alum (my current favorite) is available in the spice aisle of the grocery store and is used to make pickles from cucumber!
  • Citric Acid is another cooking additive often used in middle-eastern cooking.
  • Vinegar and salt is another food grade solution that will dissolve oxidation.

All of these work faster when heated (Beware! Hot vinegar smells horrendous). Dissolve citric acid or alum in water until no more will dissolve. I usually heat a small bowl of water in the microwave with the alum in it, then carry that back to my bench and drop in the metal. You can keep it warm by setting the bowl of hot pickle on your coffee cup warmer. You might also want to invest in a mini crock-pot.

  • Because metal clay is porous, the pickle (and patina solutions) may get drawn into the body of the metal. To neutralize it, boil in baking soda and water. (I just soak mine in warm water and baking soda – I don’t boil it, but that’s advice I’ve heard before).
  • Be sure to use either copper or bamboo tweezers to remove work from pickle that you want to use again. Steel will contaminate it and next time you drop in a piece of silver, you’ll take out a copper coated silver piece.

THE SOLDERING STATION

Setting up your first soldering station doesn’t need to be time consuming or expensive.

  • You already have a fire-proof surface in your home! Know what it is? Your stove of course. Hopefully, your stove has a hood that will vent any smoke and fumes to the outside of the house. If it just blows smoke around instead, don’t use it. Just make sure all the windows are open and you’re wearing a mask. Other types of fire-proof surfaces might be a cookie sheet, ceramic tile, fire bricks, cement board or even a pizza stone.
  • Ventilation is very important. Breathing fumes of any kind is not healthy – even the fumes from cooking steak on a grill. As stated above, if your stove hood has a fume extractor, you can use that. Open windows may be adequate, but are better if you can insert a box fan to draw fumes outside. If you aren’t able to use either of these methods, you can buy a small, tabletop fume extractor for around $60.00.
  • Don’t solder directly on the fire-proof surface we were talking about. You also want a soldering board. There are many different kinds of soldering surfaces which have different attributes that aid the soldering process in different ways, but I’m only going talk about a few.
  • My favorite is a soft Solderite board. Solderite is soft enough that you can stick T-pins into it to hold your work, dig small indentations to accommodate something like a bail so the work lays flat, and it doesn’t fall apart or crack with wear like some fiber firing boards do. (I also use a Solderite board inside the kiln)
  • Honeycomb is a hard, ceramic material covered with little holes. The holes help to dispel heat, but are also helpful when stabilizing work with T-pins. I’ve only used these in a class long ago, so have no real opinion on them.
  • Charcoal reflects heat the best, eats up the oxygen and provides a “reducing’ atmosphere for melting metal, granulation, and soldering. I don’t like these because they’re dirty (or maybe they just make my fingers dirty), and break with use. And I just don’t do the kind of work where a charcoal block would come in handy.

My soldering station consists of my Ikea table, a cookie sheet, on top of which I have a rotating pumice pan (I like the Lazy Susan aspect of the pan, and I bought it years ago because I thought it ‘looked professional’), and a couple of Solderite boards that I can stack if I need to for some reason. I also have a table-top fume extractor from Rio (which is great when I remember to turn it on).

I like to sit as I solder, other people prefer to stand. The kind of table you’ll use is dependant on your position. Try both ways to see which you prefer.

Beaducation video – Setting up a home soldering station https://www.youtube.com/watch?v=OyhVQkVUqHA

My Pinterest board on Creative Studios
https://www.pinterest.com/lorahart/creative-studios/?eq=studio&etslf=5116

THE FUEL

  • When soldering silver the entire piece needs to be up to temperature in order for the solder to flow. You can’t ‘heat the north’ and then try to ‘heat the south’. So you will be limited in size and weight depending on what you’re trying to solder and what torch you’re using. The beauty of doing simple soldering is that you don’t need an expensive, ‘professional’ torch. Any torch you can buy at the hardware store will do the job perfectly.
  • Butane which burns at around 2500ºF is not only handy for torch firing metal clay, it’s perfectly serviceable when soldering smallish metal elements. The largest item I have soldered without using any other kind of aid was about 2” x 2”. Butane gas canisters can be more expensive to buy than propane or MAPP, especially at the hardware store, and I prefer to buy larger canisters online than I have been able to find at a ‘brick and mortar’ store. ‘Triple Filtered” butane seems to burn cleaner and last longer. I always make sure the torch is full every time I use it. Filtered Butane
  • Propane/atmosphere (air) burns hotter at about 3596ºF and the disposable canisters are easy to find at any hardware or camping store. The olive green camping canisters are shorter and larger around and seemed more physically stable to me than the taller, narrower, blue ones from the hardware store. Same gas, similar cost – just a different profile.
  • MAPP (in a yellow canister) is actually a blend of propane plus propylene and burns the hottest at around 3650ºF.
  • Secure the tall, narrow, bottles of propane or MAPP gas to your table leg with a bungee cord so it doesn’t fall over.

THE TORCHES

  • There are any number of butane torch types. My preferences are the Max Flame for a full, bushy flame to solder larger projects and the Blazer GB2001 for a sharper, pointy flame that’s perfect when soldering jump rings and smaller projects.
  • I suggest a flexible shaft torch head for both MAPP and Propane. If you get a torch that connects directly to the threaded opening of the canisters – you’ll be holding the canister as you solder, which (for me) is awkward and causes hand/arm strain over longer periods. Unfortunately the exact Bernzomatic torch I started with has been discontinued but the Bernzomatic BZ8250HT looks like a good replacement and I’ve heard great things about the EZ/Orca torch.
  • When you’re ready to switch to a gas/oxygen torch (as opposed to the gas/air versions I’m referencing in this article), you’ll be able to look into even more torch options.

 

This video describes the process of setting up and using the EZ torch by Janet Alexander. “It is a nice compact torch that attaches to a small propane canister, like you use for a camping stove. The fuel lasts for quite a long time using it with this torch. Since I travel teaching metal smithing I use this torch for my classes. I can pack it in my checked luggage and then after landing buy my fuel. This torch is good for silver soldering, sintering metal clay, torch firing enamel, and melting small amounts of non-ferrous metals for casting.”

Also a good video by Kate Richbourg.

EXTRAS 

  • Third Hand – This gadget has a heavy base (so it won’t tip over) and a cross lock tweezer connected by ball bearings so you can position it in many ways. The tweezer can hold small items like earring posts, (which I love because my own hand tends to be unsteady and unable to hold a connection). I have two third hands. Couldn’t live without them.
  • Enameling trivet to hold work up in case I need to position the flame of the torch underneath the item. I don’t like the large soldering tripods. Too much metal, and too much of a heat sink for what I do. I just place the trivet on my Solderite board when I need to use it.
  • Titanium picks usually come in packs of three. Solder doesn’t stick to titanium so you can use it to pick up a tiny ball of solder and place it just so, or move a pallion back into place if boiling flux disturbed it, or just push ‘this thing’ closer to ‘that thing’.
  • Binding wire is another fabulous helper to stabilize and hold two or more parts together during the soldering process. You can buy powder coated steel wire at the hardware store to use as binding wire. First use sandpaper to sand all the powder coating off.
  • T-pins, coins, small sheets of titanium and other props all come in handy when trying to find the best way to position your work to make soldering easier.
  • Water based ‘Liquid Paper’ or jeweler’s yellow ochre can be used to stop the flow of previously soldered joins to prevent them unintentionally re-opening.
  • If you don’t have access to good ventilation in your soldering area, you might want to invest in a Fume Extractor. The inexpensive version sucks the smoke (from burning solder) in and sends it through a charcoal filter.
  • Water! Always have water nearby in case you get burned (don’t do that) or to quench your hot work. I use a ball jar, so I can lock it down when I’m not using it. Ask me how many bowls of water I’ve spilled in my career…
  • I keep real vanilla extract in my studio to put on slight burns. After running cool water over the burn, I just spread some extract on the area and let it soak in. The next day there are never blisters, and it doesn’t hurt!

**NOTE**  I was taught never to quench a piece of red hot metal for fear that it may shatter like shrapnel or fling droplets of boiling water onto my body. It just takes a few seconds for the color to fade – indicating that the metal has cooled to an appropriate temperature.

Next week we’ll share more soldering project tips and examples by Lora!  Stay tuned.

LORA HART was born and raised in Los Angeles, California, and moved to historic Richmond, Virginia in 2012. Lora is the Artistic Advisor and one of twenty Senior Instructors for PMC Connection. A metal clay artist inspired by historic imagery, Lora’s work has been featured in books, magazines, and calendars and her jewels are sold in galleries and online. As a designer, educator, and creativity coach, her passion for the art and business of jewelry making has taken her across the United States to help other makers explore their own passions, develop their craft and expand their skills.

www.lorahart.com @lorahart