I have been making jewelry for a long time and I’ve had bad soldering days, but lately it’s happening way too often in my home studio. My metal and solder are clean and I’ve cleaned them again and again. I’ve tried switching fluxes, using different batches of solders, and the problem persists. What are some other factors that can affect solder flow? Are there environmental factors that can have an effect?
More information needed. What gas? What torch? What metal? Use a barrier flux? What’s your flow flux?
Acetylene air. I don’t know the brand of the torch but it’s the regular kind, not a mini torch. The metal is silver at the moment. I have a few different fluxes. I started with Battern’s and switched to a Rio liquid flux. I’m out of paste flux but was wondering if that would have made a difference.
I would definitely use a barrier flux. Boric acid and denatured alcohol. I prefer paste flux. It melts at around 1200F so you know that the solder is approaching melting temperature.
There’s a short video I made but even compressed it was too big to send. Just under 2 minutes. I’ll ask my son how to send it. I just realized that I can send it on FB Messenger. So PM me and I’ll send it to you!
More information? What is happening specifically? Does the solder just sit there, does it melt and not flow, does it partly flow? Is it ALL grades of silver solder? Wire or sheet or paste? What kinds of surfaces are your parts sitting on, how do you hold them together? And on and on. Lots of things affect soldering and I have run across seemingly “bad” batches of solder and fluxes both.
We have an air/Acetylene torch here in our employee studio and after coming across issues, I’ve written this article about the problems that we’ve faced. I wish I knew more about your set-up, mainly torch tips and soldering surfaces, but here’s a link to the article and hopefully it will help resolve your issues:
Top 5 Reasons Silver Solder Doesn’t Flow
Here’s something that I’ve seen happen frequently with students- the solder doesn’t flow, but everything appears to be correct. The parts fit, they are clean, there is flux, the solder touches both surfaces- but there they would be torch in hand for 10 minutes, 15 minutes, far longer than solder normally takes on most jewelry pieces. Why?
It’s all about heat control. Not enough heat in the right place. If they heated the piece up over annealing temperature, but below soldering temperature, it was a lost cause after a certain amount of time. In frustration they would finally crank up the torch or have a friend add another torch. They didn’t know it, but the solder would probably never melt and flow. Holding things at annealing temperature for a long time depleted the zinc from the solder, this changed the melting point by raising it.
The way around this was to get enough heat into a piece from the beginning and quickly. Add the punch of heat to get the solder to melt and flow and then get out. Know where the hottest part of the flame is and what type of flame you are using. (And yeah, there are days you can’t do anything right, much less solder or set a stone.)
I do think flux gets old. Solder can oxidize, but unless you’ve cut it into pieces, you should be able to clean it with an abrasive pad. I’ve used solder that was 20 years old without problems, so I don’t believe it can go “bad”.
My brother Rob and I have been building sterling jewelry for I would guess more than75 years between us. Rob longer than I. There is some similarity in our work but a lot of difference. One of the things we both notice is that about two or three times a year we find we have to earn how to solder all over again.
In my case I go through the inventory of ills.
Is the work clean?
Are joints tight and clean?
Is the flux fresh?
Is the solder clean?
Is the torch clean?
In my case it almost always comes back to the torch and heat. I am recent to the Smith Little Torch, propane/Oxy. When I used a Prestolite (Acetylene/Air) torch I relied on the sound of the torch as much as anything to know what the heat was. I can’t do that with the Smith Torch. Still it is heat. How it is applied, how big the tip is, and what I am using for flux. The Little Torch has a different learning curve because of the size of the flame and how it develops heat.
I am more likely to be too hot. The thickness of the metal, especially 10 ga. wire will heat up on the outside to the point the solder will flow around the perimeter of the wire but the interior will be cooler and the solder won’t flow through. It will look picture perfect until you try and shape that metal and it will break at the joint as it bends.
I have a three failure rule in the shop. If the same problem fails three times in a row. I clean the shop, have a cup of coffee, and I take a nap. Then I start over with some scrap, learn the sound of the torch as it burns through the tip I am using.
Eventually the planets realign and I am producing work again. I my case once I have eliminated the possibility dirt or contamination it is almost always heat.
Hi Don & Ruthannie-
Thank you both for the very good advice. I posted this issue a long time ago and haven’t had the problem again. For the particular case that was frustrating me, it turned out the problem was that the torch tip was too small. Soldering has been going just fine since (mostly).
Don, I can so relate to issues of moving to dual fuel. I too, used a Prestolite air/acetylene, and I too, relied on the sound! still dealing with my learning curve now that I do nat gas and oxy with a Meco.
Great advice. I certainly can relate to soldering issues.
I just wanted to say, I adore you for posting this. I’ve been smithing for two years. Long enough to feel comfortable and like I know what I’m doing at least on the basics, but short enough that when I have one of those bad days it still makes me question whether I know anything at all! Knowing it happens to everybody makes it a lot easier to take a moment, shake it off, and start over.