Brass and different types of flames?

Hello everybody, I am working with brass to make mixed metal pieces. Curious if anybody has any tips or pointers that they have learned along the way. I find that the jewelers brass I am getting from Rio has a beautiful color that looks a lot like 14 karat gold, but at a fraction of the cost of silver.

For some of our customers who would like to keep the cost down this is a choice they choose to make.

When I’m working with the brass, I am noticing that it responds differently to an oxygen, propane flame then to appear acetylene flame. When I’m making little balls, the oxygen acetylene flame often times causes the brass to get balled up in a crunchy lobby way but the acetylene flame caused it to ball up nice and tidy. Any ideas why that is?

Any other clues or hints or tricks would be appreciated!

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I don’t really know why that would happen?

With the oxy/acetylene flame, you can make a reducing flame (too little oxygen), neutral flame (the right balance of oxygen and acetylene) and an oxidizing flame (too much oxygen) With the air/acetylene flame, it’s essentially a cooler, non-adjustable neutral flame. If I was to guess, I’d guess that you’re not melting the brass with a neutral flame when using oxy/acetylene. That’s just a guess.

The other factor is too little flux. Brass has such a high copper content that it doesn’t melt easily without flux. Also, it’s pretty easy to over heat it and burn up the flux and the tin and zinc in the alloy.

That’s the best that I’ve got!

Jeff

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Is there any place to read up on working with brass that you recommend?

I think I overheated those balls.

Jewelers brass, which is what it sounds like you are using, is an alloy of 85% copper and 15% zinc. Zinc boils at a temperature lower than that at which brass melts. So the little balls that you have melted are more copper than brass. It’s possible that the zinc boiling off may have an impact on the physical characteristics of the new alloy that you have produced in the process. Try melting a small amount of pure copper and jewelers brass side by side with the same torch and see how they behave. Let us know what you find out…Rob

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My guess is that the oxy-acetylene flame is creating more of a reducing atmosphere locally, so the zinc in the alloy isn’t oxidizing as much.

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I find that very often my Little Torch’s flame is too forceful, too narrow, and way too hot for brass depending on the cross section of the metal. I find that I have a better outcome with a wider, less powerful, flame. I will break out the old Prestolite plumbers touch for some projects.

Depending on the project I tin the two surfaces separately, boric acid and alcohol for sterling and Battern’s for the brass. Then a scrub with a brass brush and they can be joined. Now you are joining two soldered surfaces instead of dissimilar metals. I usually use boric and alcohol for this step but green flux will work well too. I use this method applying decorative sterling to wide heavier pieces of brass. More plumber like I suppose but it gets the job done.

Don.

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Some brasses have copper, tin and zinc, but Rob is correct, jeweler’s brass doesn’t have tin. It’s just copper and zinc with a little bit of lead. I forgot that. As everyone is mentioning it’s really easy to burn off the zinc.

I’d definitely use flux (paste flux is fine) and heat jeweler’s brass to as low of a temp as possible to create your balls.

I don’t know if the jeweler’s brass SDS is helpful, but it might be good to know specifics.

Also, if it’s not jeweler’s brass, there are a zillion brass alloys, that all may melt differently.

I’m not a fan of melting any metal with zinc in it. I’ve had way too many zinc fume headaches in my life.

Two of my favorite alloys are a pure bronze alloy of just 90% copper and 10% tin. Rio Grande sells it as Ancient Bronze in casting shot form (meaning little balls that are already made!) It might be worth buying a little bit to see if that solves your issues.

Another of my favorite alloys is Shibuichi, a Japanese copper and silver alloy. Shibuichi is basically bronze that switches out silver for tin. You can make it with a variety of silver/copper proportions for different colors and hardnesses. 75% copper & 25% silver, 85% copper & 15% silver, etc. The one trick is to melt the higher melting temp metal first (the copper). I don’t think anyone sells Shibuichi these days, so you have to make it, but it’s really easy.

Best of luck!!

Jeff

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I make several of my standard bracelet designs in jewelers brass. It is a lot of fun to work with, but a bit tricky to solder. I have tried different brass solders, but find that silver solder works the best for me. I would be interested in hearing how others solder jewelers brass. I haven’t been able to melt it because my torch just doesn’t produce enough heat. My new furnace will, but I haven’t tried it yet…Rob

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Thank you everyone, going to do some study and incorporate your wisdom.

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I’ve worked with mixed metals including copper and brass. Brass is very difficult to solder in a controlled manner as the zinc content in it makes its own solder upon contact with silver… Jeweler’s brass is technically C226 brass which is 85 to 90% copper with the remainder zinc. Just googling jeweler’s brass gives a wide range of compositions from 1/3 zinc to 2/3’s copper and on up with more copper. Brass and sterling melting points are overlapping. The more zinc in the brass there is, the lower the melting temperature and the more self soldering happens… I did some metal inlay work by embedding brass and copper wire into silver by melting… it’s nearly impossible to control. Doing applique work with brass and copper decoration is also very difficult to control… use only the lowest melting point solder…

A hot flame is definitely NOT what you want to use… Gas/oxygen torches are too hot… I used a propane air disposible cannister torch… even so, working with mixed metals at a lower flame temperature was extermely tricky…just slight overheating would melt everything down. Jeff’s point about using a lot of flux is well taken. Flux prevents zinc oxidation, zinc fumes, and changing thecomposition of the brass as the zinc burns off…

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Interesting topic about solder. During a visit to Buenos Aires I roamed the jewellery district that remind me of NYC. The tool shops only carry the classic silver Hard/medium/easy solder and a solder called 730 with 30% silver for alpaca/brass/copper.
Far from there I visited a base metal supplier catering to craftsmen working with Alpaca/brass/copper, to my surprise the solder available was not Hard/medium/easy but rather rated by % silver from 60 to 20%, my guess is that users are looking for color match, the lowest silver content recommended for copper. I believe these solders are standard DIN/ASM formulations with high melting points.

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Would you say that the 30% and 20% solders were a good color match for brass and copper respectively? I’ve been looking for something to use with these metals that didn’t contrast with them as much as regular silver solders do.

silver/copper alloys have a eutectic point of about 78 weight % silver and 22% copper… the lowest melting temperature for a silver/copper alloy at 780 degrees C. The atom percent silver is lower, as silver atoms are heavier than copper atoms… that would make the eutectic point closer to 60 atom% silver and 40 atom% copper… more copper will raise the melting point, as would more silver. Silver brazing rods are at the eutectic composition. The alloy color goes from silvery to greyish with more copper… to achieve a gold colored or brass colored, the copper content has to be high- 30 weight% silver or less. From the table above, you can see that the melting point rises steadily with a lower silver content. The higher melting points are still relatively low…750 C is around 1,380 F…amarillento is yellowish in Spanish…Plateado is silvery…

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certainly agree that a low temperature flame is desireable. tining first is an igenious solution… thanks for the input.

the presence of zinc lowers the melting point of everything it touches. I don’t like it either, as zinc alloys are difficult to control. they can have very low melting points, as low as soft solder, depending on how much zinc is in it.

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