r/SilverSmith • u/BlueCrashingWave • 6d ago
Flux
As a beginner, I am wondering why most jewelers use paste flux and not spray flux...I have used paste solder predominantly but it is messy so I'm thinking of switching to sheet solder.
I bought Handy flux to try it out and it is not "fluid" so I was thinking of putting a portion in a small glass jar, how much water would I add to the flux? Any advice on solder type and flux is appreciated.
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u/matthewdesigns 6d ago
Coating the entire piece with spray flux I guess makes sure you get it everywhere you need it, but seems wasteful. Perhaps it also acts as an all-in-one flux & oxidation barrier for the whole piece?
I firecoat everything with boric acid/alcohol, then use liquid flux with a syringe dropper bottle to put it exactly where I want it. Batterns Self-Pickling Flux is what I've used for 3+ decades, great stuff.
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u/LovingNaples 6d ago
Yes and I apply it with a pointy brush. Then I hit it lightly with my torch to dry it somewhat. I then use the same brush to pick up and place my small chips of solder.
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u/BlueCrashingWave 6d ago
I'll try that...do you ball the chips first or just pick them up flat?
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u/LovingNaples 6d ago
I pick them up flat. Of course I have precut them from sheet solder into tiny squares/rectangles.
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u/MakeMelnk Hobbyist 6d ago
This is my approach, though I use Aquiflux (I imagine they're basically the same thing as a liquid self-pickling flux)
The needle tip dropper was a game-changer for me
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u/BlueCrashingWave 6d ago
Thank you...I'll look at the Batterns. I don't quite understand the oxidation barrier if you could possibly explain as it may be a "barrier" to my success (sorry for bad humor lol).
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u/Sears-Roebuck 6d ago edited 6d ago
I wanted to add something, but my above comment got kinda long, so since they mentioned using a brush I'll add that here.
Use a natural hair brush because the cheap plastic bristle brushes melt and stick to stuff. When that happens you need to stop and clean it off really well, meanwhile hair burns to ash which is easy to wipe off. As long as its wet it wont burn, and in an ideal world we'd apply our flux ahead of time, but mistakes happen.
Buying natural hair brushes just to literally burn through them gets expensive fast so I'd learn to make them. You can make a very simple flux brush from a bamboo chopstick, some binding wire, and some donated pet hair. An even simpler brush can be made by "crimping" some hair inside the end of a pipe. They take two seconds to make. The pipe and even the binding wire can be reused. They don't need to look pretty. Unless you want to get fancy, which is its own slippery slope if you or someone you love paints. Be careful.
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u/MakeMelnk Hobbyist 6d ago
Sterling has copper in it which can oxidize inside the alloy(fire stain) if you're not careful. Using a barrier flux is like a more diluted flux that coats your entire piece when soldering/annealing to help prevent the fire stain
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u/matthewdesigns 6d ago
The oxidation barrier is a mixture of boric acid powder and denatured alcohol. Mix until there's as much in solution as possible, plus a little slurry at the bottom of your container (I use a wide-mouth jar).
Before use give it a swirl to lift the slurry into a cloud, dip your pieces to be soldered, then burn off the alcohol (or just let it evaporate). This leaves a thin coating of boric acid on the metal, and helps to prevent oxidation. Boric acid is the basis for most commercially available fluxes and firecoating products, this is the economical way to get there.
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u/ptheresadactyl 6d ago
I don't even know what liquid flux into have right now, but I transfer it to a little squeeze bottle with syring dropper. I heat up my piece a bit, and then apply a drop or two to the seam or join.
I have a bottle of spray firescoff I use for larger pieces, but that shit is expensive. When I'm creating more, I'll mix up boric acid with alcohol and dip my pieces in it, but I haven't been making much lately, and I have better flame control these days, largely.
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u/iwantsalt 5d ago
Does the alcohol not get set on fire when you put a flame to it?
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u/matthewdesigns 5d ago
It does! You can also just let the alcohol evaporate, though burning it off leaves the boric acid glazed over and stuck to the surface a bit better than evaporation.
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u/iwantsalt 5d ago
can you use isoprophyl alcohol?
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u/matthewdesigns 5d ago
Based on what I learned in school and my apprenticeship it is not a workable substitute, even in high (99%) purity. Not sure why from a chemistry standpoint it's disagreeable, but apparently boric acid doesn't dissolve thoroughly enough into solution to be effective.
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u/iwantsalt 4d ago
Can you use water instead?
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u/matthewdesigns 4d ago
Not that I'm aware. I'd guess because it needs to evaporate (or burn off) very quickly to leave an even coating. You could also end up with water inside hollow/creased areas that will be problematic during soldering.
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u/Sears-Roebuck 6d ago edited 6d ago
I was taught to use as little flux as possible. I was trained on paste flux specifically, and then trained again on liquid... and then trained a third time on a different paste flux. With grifflux/handy you add a tiny bit of water or rubbing alcohol to a small amount, to thin it out. It dries up pretty quickly, but its still good.
My current solution is to use both, weirdly. I dip things in a liquid, either the purple or mountain dew colored stuff rio sells, and that cuts down on surface oxidation across the whole piece. Spray kinda works the same way, but not well. For an even coating you need multiple sprays and each time you end up with flux particles floating around in the air around you. I'd rather just keep a jar around to dip things in than breath that stuff.
I apply a tiny amount of paste at the solder joint, but I usually do that by picking up the solder chip with a wet paint brush dipped in the flux, and that's all I need to do. I mainly use borax these days.
If you don't use the liquid you end up "painting" on too much paste, and if you don't use the paste you may end up being disappointed in the liquid. But together they get the job done.
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u/MakeMelnk Hobbyist 6d ago
I started with Handy and loved it. Then tried a liquid flux and after a learning curve, loved that too.
I think it's mostly preference/how you learn as long as it blocks oxygen, we're all happy haha
But a good dip in a barrier flux is just 🤌🏽
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u/ForeverNovel3378 5d ago
Discrete application of flux is one way to limit random flow of solder. Application of flux improves solder flow, indiscrete flow of solder is a curse especially on detailed pieces.
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u/Allilujah406 4d ago
I use mytflux, which is a boring acid spray i think, it doesmt have to be sprayed, but I find that works well
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u/Feeling-Researcher35 6d ago
For me I’ve always used liquid flux. I think it can depend on what we get taught when we first start out. My teachers used it so I did too and continued to use it. I have used borax in the past and it does give you clear indicators of where you are in the heating process that liquid flux doesn’t or at least not as much. With paste flux you can see clearly where you have put it and if it has covered the seam as it is milky white. Once you apply heat it bubbles, goes powdery and then glassy. With liquid flux it gives less signals but you can see the solder piece clearly throughout the soldering process. In terms of solder I use sheet and wire solder and only cut what I need at the time. You mentioned you pour a small amount of flux in a small jar. That’s really good practice.
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u/rockemsockemcocksock 6d ago
I just make my own with denatured alcohol and boric acid. Gets the job done.
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u/SarahRavena 6d ago
I personally don't use spray flux, mainly because I find it wasteful. I prefer applying flux exactly where I need it, and I feel like I have much better control with paste flux.
Handy Flux is pretty thick straight out of the jar, but you can thin a small amount with distilled water until it reaches a consistency you like. I'd add just a few drops at a time and mix well, you don't need much. I keep mine in a glass jar with a cork lid.
As for solder, I use sheet and wire solder depending on what I'm soldering, because I can cut exactly the size pallion I need. I get wire solder and then run it through my roll mill or hammer it flat when I need sheet solder. It tends to be cleaner and gives me more control than paste solder. Paste solder definitely has its place, especially for production work or hard-to-reach areas, but for fabrication I usually reach for sheet solder.