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Firescale preventative and flux


I was just wondering what everyone’s preferred flux for silver is and do you use firescale preventative like cupronil? I’ve been using borax and water with inconsistent, unreliable results. I’m guessing because I’m inexperienced. I’m looking for a flux with a reasonable price point and fairly reliable results even for a beginner with a reasonably fair understanding of ideal conditions for a perfect join. Like clean components, completely flush joints and heating the piece evenly. My preferred supplier is Rio Grande. A firescale preventative and flux in 1 would be even better. But if the preventative isn’t entirely necessary, I can wait on that.

Thanks in advanced!


Search the Orchid archives for Prips flux. A mix of 3 parts boric acid, and two parts each of borax and trisodium phosphate (TSP), MIXED IN water. I use 120 grams boric and 80 grams of the two others in a quart of tap water, then add additional water till it all dissolves. You can make it more dilute. Be sure your TSP actually is trisodium phosphate rather than a substitute cleaning agent. To use, preheat the clean metal until you can spray the Prips on and have it instantly dry, forming a thin white film. Cover all surfaces. Additional flux may help solder flow, but isn’t absolutely needed if the metal was clean. I typically flux the solder pieces as I apply them. Used right, Prips will prevent firestain and firescale on standard sterling. The slight extra effort to apply it is more than made up my less cleanup, and making it yourself makes it cheap. If you can’t find YEP use Calgon dish washing powder. Be sure it’s the green box that specifies a phosphorus content.


I started out using Handy Flux, but wasn’t really happy with it; I found it difficult to use, though I concede now that my skill level may have been to blame.

I started using Jel-Flux, and love its clear, easy to apply body. I use fine watercolor brushes to paint it onto my work pieces, both for joints and as a surface protection. Most of my soldering is done with silver pallions, and they position easily, and stick right where I want them with this stuff.



Hi Rachael,
Ted here in Dorset UK, the odd one out as im a jewellery maker amongst many other metal processing techniques whos w/shop and techniques are on an industrial scale.
So, I approach problems like yours from the industrial perspective and use industrial fluxes, instead of medieval alchemy ways to flux work. thats not to say borax etc dont work, they do, but you need to be taught how to use them.
In the absence of mentor, Peter Rowe’s recepie is the first to try, he is probably the most experienced precious metal worker here on this forum.
Have a go and let us all know how you get on, that way, we can help you better.
Now I never need to use borax or Pripp’s formula, as there are much better fluxes out there for the silver and gold work I do.
I use just one, its the reactive flux for s/steel made by Johnson Matthey here in the UK, and available world wide from all welding supply businesses.
Why use an inferior product? when a much better one is out there we live in the 21st C. Not the middle ages!
This flux actually dissolves out fire scale from silver, but I never get that even with repeated heating.
hope this helps.


Ted, you flatter me. And yes, I’ve been doing thus for much if my life. But I assure you I am neither the most experienced nor the most knowledgeable of the jeweler and metalsmiths on this forum. I just tend to get wordy. But there are any number of people here who’s skills as artists, craftspeople, goldsmiths, and more, dwarf me by quite a margin, including yourself, for the work you specialize in.Peter Rowe


I use Cupronil for all my soldering.It is easy to apply with the spray bottle and is relatively inexpensive. I have tried Fire Scoff but it is very expensive and trickier to apply and work with.


I have used Batterns and other liquid fluxes as well as a borax cone and water. Right now I like Handi Flux the best, usually mixed with a little water. I spoon it out of the Handi Flux container into a small storage container with a tightly sealed hinged top. You can buy them at arts and craft stores. Use it liberally and keep it wetted with water as it will dry out fast. I also keep Pripps on my bench in a sealed bottle and apply it with a mouth powered glaze spray atomizer ($1 each on Amazon). They don’t clog up like a pump sprayer. I also have used a mixture of alcohol and boric acid for small pieces. You have to burn off the alcohol, so be careful that you don’t set the entire pot on fire. If you are soldering a big piece with a long joint, you may have to pickle and reapply flux several times as it burns off. There is a lot of information in the archives and other sources so take the time to do some research. Don’t be afraid to experiment. Flux is important, but so too it a clean bench, clean material and clean solder. If you have trouble soldering, stop clean your work area and materials, make sure your torch is adjusted correctly, take a break and then try again. You will know when it is all working when you see your solder flow evenly in a small fluid flash of light along the joint. For silver especially, you need to be sure to heat the entire area away from the joint as well as the joint. Don’t point the flame directly at the solder but keep it moving until the solder flows. I use solder pallions a lot for my flat surfaces, but when my joint is curved like when you are soldering two pieces of round wire together over their length, use small pieces of round wire solder. It fits the joint better and flows more evenly and predictably. Good luck…Rob


Ted, does the flux have a product name or a parts number?


Sent from my Verizon 4G LTE Droid


Hi Don,
I have the white pvc container in front of me.
it contains 500gms of powder.
Its called Johnson Matthey Easyflo
Stainless steel grade. Majenta coloured label.

Product Nr. 814179
After use hot or boiling water soluable, as well as dilute h2so4 hot or cold. This is needed because brazing bronze to 316 stainless needs acid to remove stainless steel oxides.
their email address is
Primarily designed for silver brazing of s/steel. Contains active flourides and needs to be used in a well ventilated w/shop.
hope this helps.
working range 550 to 775 deg C.
I do need this quality grade as the joints after brazing have to be ductile and strong enough to be forged into curves.
nothing else does the job. some bends are 90deg . and dont break!!.
Its not just sticking 2 bits of metal together!.
Hope this helps, and please let us know how you get on
with it.
Instructions in use on label, either mix to a runny paste or apply dry off the brazing rod.



I use an anti fire scale formula for both Gold and Silver that I learned from old farts who learned before WWII. 1/2 powdered boric acid and 1/2 denatured alcohol for a fire coat. Easy to make and the alcohol just burns off in a flash leaving a fine coating of boric acid. If I am soldering a fine chain or something small like a jump ring no flux is needed. Just the fire coat.
For both Gold and silver I prefer a good white paste flux like Handy Flux. Liquid flux doesn’t hold up very well on silver. It burns away by the time you’ve got your silver hot enough.
Have fun and make lots of jewelry.


Thank you Ted. I appreciate your time as always.


Sent from my Verizon 4G LTE Droid


Thank you all so much for your replies! :slight_smile: I may try the handy flux for ease of use first. I’d like to hone my skills and get my soldering skills to the point where I don’t run into this problem continuously.

Your help has been invaluable to me, so thank you so much! :slight_smile:


Good, evening Peter, touche!
I omitted to mention that your prepared to give a formula that will work for and by an inexperienced beginner.
Many superb craftsmen/ women dont.
Nuff said.


Ted, yes, i share things I know. It’s only fair, since I only know them because someone shared with me. Prips flux was the method used and taught when I was an undergrad at the University of Wisconsin, first taught to us by Fred Fenster, who of course was mostly passing on what he’s learned from Jack Prip…


I was taught to work in silver by an accomplished amateur, Will Smith, who taught at the Middle Tennessee Gem and Mineral workshop in Nashville. He had beginners use only medium, easy and extra easy solder. The temperature chart he gave me shows that fire scale formation begins at 1400F, and that medium solder melts below that temperature. His thinking was that if you were careful your piece never reached 1400F and you didn’t have to deal with firescale. I only made a few pieces under his direction, but I didn’t have any perceived problem with firescale. Of course, this will only work if you are careful and don’t overheat your work. I’m interested in whether the pros have any comments on this approach, since there is another prominent on line teacher who states he never uses anything but hard solder. Since there really isn’t any difference in strength between the grades of solder, I don’t see why the late Mr. Smith’s approach won’t work…


Hi Royjohn,

Hard silver solder has greater diffusion and thus gives a stronger join. It is also closest to the color of sterling. I usually use only hard silver solder, but of course there are special cases that sometimes require medium or soft.

Janet in Jerusalem


So how would you prevent subsequent joins from melting?


Hello Kawaiidragon,
Although you don’t specify, it sounds like you are using standard Sterling. I was taught metalsmithing with standard Sterling decades ago, so used it for years.

However, may I suggest that you try working with Argentiuum Sterling (AS), especially the AS solders. There is much in the archives about the differences between AS and standard Sterling. In a nutshell, AS is tarnish RESISTANT, does not fire scale, is a whiter color, work-hardens more slowly (and can be hardened in a toaster oven), and solders very much like gold. On the downside, it is brittle when hot and large pieces will slump if unsupported. Price is slightly higher than standard Sterling. I get it at Rio Grande. Check their website for technical info. Stuller carries two other tarnish resistant silver alloys, each with different benefits. The website also has technical info.

I only use AS solders, even on the regular Sterling that I still have in my stock. It is a better color match and in general flows at lower temps than the other silver solders. What’s not to like. It least try the AS solders to see if you have more success.

Judy in Kansas, who sees a lovely day and would like to get out and put some time into cleaning up the garden, but will stay at the bench preparing some pieces.


So how would you prevent subsequent joins from melting?

I often do dozens of solderings on a single piece. I’ve never had previous seams come apart. Every time you heat the piece, the solder diffuses a bit more in the previous seams and thus raises the melting point of those older seams. So the amount of heat needed to make your newest seam (i.e., the melting point of the solder) is always less than what is needed to open the older seams. So older seams should not come apart unless you overheat. If you’re into the science of metalworking, this is a basic area to study.

In theory it’s very easy, and it should be in practice, but it would probably help a great deal if you could see an experienced jeweler at work. If you get an only propane torch (no oxygen or air tubes) like the one I suggested a day or two ago (perhaps on a different thread?), you will get a nice big bushy flame which is perfect for doing multiple solderings on silver. The high-heat torches (e.g.,mini-torches) with a hot, concentrated flame are much more likely to cause melting of old seams. Sounds like you need a few soldering lessons from a master. When looking for a teacher, perhaps you should choose one who is used to doing many solderings on a single piece with fine wires/bits…:-)… I could be wrong but I believe highly skilled soldering is much rarer now than it was when I was starting out (about 40 years ago)…

Janet in Jerusalem


Thank you! Yes, i use standard sterling and 999 bezel wire. That might be another experiment I’ll try. I’m starting with my flux. I got some handy flux to see if my borax and water is the culprit. If I still have problems, I’m going to try a different torch. I may just pick up a ft or 2 of AS solder. Is the density the same as sterling?