Silver soldering - Copper vs Brass

[rtropp]

Hi all,

I am running into some problems silver soldering.

 

I am trying to fabricate gudgeons using .016 thick copper sheet with copper tubing.

My set up and technique closely follow the lessons available on Youtube, Rio Grande supplier and Beadalon.  I have tried a number of variations, all with careful cleaning etc.

 

I cannot get the wire or paste solder to fuse the copper tube to the copper sheet.  I figured I was doing something wrong but then I tried the same with a brass sheet and brass tube.  No problem, the brass fused in under a minute with the paste or wire.

 

I am listing my set up in case that helps.

 

A Blaze torch (rated 2,500 Degrees Fahrenheit), 

 

Paste solder:

Paste Solder For Brass, Bronze, Copper and Yellow Gold-Filled

Item Number: 503053

Form: Paste

Metal type: Base metal

Liquidus temperature: 1,140°–1,500°F (616°–816°C)

Country of origin: United States

 

Wire solder:

Gold filled wire with solder inside

18 gauge wire, 0.4mm diameter, 18 inches long

Melt 1315 degrees F, flow 1500 degrees

Use for all gold filled jump rings and chain; not pure gold solder

Karat/purity: 14/20

 

Both solders have flux built in but I even tried adding flux in some attempts.

 

I cannot figure out what is going on. Brass works without a problem, copper does not. I suspect I am overlooking something simple but it would make more sense if neither worked.

 

I would appreciate any thoughts.

 

Richard.

[druxey]

Are all the surfaces clean of all dirt or grease?

Are the surfaces in close contact?

 

These are the two most common causes of joint failure.

[rtropp]

Yes and yes.

They were not only cleaned with an emery cloth but also dipped in pickle before and after.

To make sure it was not an isolated incident, I repeated the solder 6 times, 4 in copper (failed) 2 in brass (worked.)

 

Richard

Edited February 8, 2015 by rtropp

[druxey]

That seems strange, Richard. I assume that it really is copper that you have there. Perhaps someone else can suggest what is going wrong.

[capnharv2]

Hi Richard,

 

I'm no expert at this, but I have a couple thoughts. . .

 

-Is it possible that the copper has some protective coat on it that hasn't come off when cleaning? See if you can scratch up the surface more.

 

-Have you tried putting solder on the copper sheet and tube individually (not soldering them together)? If the solder won't adhere to one or the other you've found the culprit

 

-How long do you leave it in acetone or alcohol before trying to solder? I've found that it may work better leaving it in for 15-20 minutes, then let it air dry.

 

-I just looked up their melting temperatures. Brass-1700 deg F, Copper-1981 deg F. So, it may be that the copper isn't getting hot enough

 

-An old article I read on silver soldering said the parts have to be in direct contact with each other. With the paste or wire, it's possible that the brass is more forgiving on gaps than the copper. I've been silver soldering with silver sheet, and it will not flow to the joint unless the parts are touching.

 

Hope that helps.

 

Thanks,

 

Harvey

Edited February 8, 2015 by capnharv2

[rtropp]

The copper sheets are K&S copper sheet, 14 gauge.

Richard.

[rtropp]

Harvey,

 

I used emery paper in all trials and could see the shine come up before setting up for soldering.  I did the same with the brass.

 

I had dipped them in a warm pickle solution, Sparex #2.  Do I need to use acetone or alcohol instead?

Also, I did not soak it for very long so tomorrow I will leave it in longer.

 

The torch has an upper temperature of 2400 F.  With the brass it only took a minute for it to melt.  With the copper I kept extending the time.  Finally, probably our of frustration, I went about 10 minutes. 

 

As I think of it now, the solder wire was still a wire an not melted for these trials.  With the brass it melted as described. I will do as you suggest and coat the tube and the sheet separately and see what happens.

 

The parts were in direct contact.  The sheet was flat and the tube was straight.  In some of the trials I made sure to apply a fair amount of pressure to make sure they were in contact.

 

Thanks for the tips, I'll will let you know tomorrow how the trials went.

 

Richard

[mtaylor]

From the solder description, it's not silver-solder.   That's possibly the problem.

[jud]

You must be holding the parts together somehow, perhaps you have a heat sink effect that prevents the copper from heating enough but will allow the brass to heat to the lower tempurture needed for it.

jud

[rtropp]

Mark,

You are correct.  They are not silver but they are sold as a high temperature solders along with the actual silver solder and supposed to act the same.  When used with the brass both performed as expected. That's what is confusing me. 

 

When I used soft solder (low temperature paste) the joint held. But, I had been advised to hard solder to reduce risk of it coming loose later.  Also there are "yellow" high temperature solders that would better match the copper.  

 

Hmm... I realize after reading your comment that I have not tried the same thing with actual silver solder.  I have some in flake form and will test it today.

 

Jud,

I am using a silquar board which reflects heat back to the piece.  I am not clamping the pieces since both are flat and stay in contact without pressure.

But, I will recheck my set up just in case.

 

I appreciate all your tips and am working through them.  I may go ahead and make the gudgeons using soft solder just to move ahead with my build, but I will continue working with hard soldering to master it.  It has become a challenge.

 

Richard

Edited February 8, 2015 by rtropp

[bear]

This might be your problem. Heating up the metal too fast,before the flux can melt and create the covering to protect the copper from oxidizing.

 

You might have better luck with 50% silver solder-cad free,wire 1/16" dia.-no flux. Use water based white silver soldering flux paste. Sand the surfaces to be soldered clean.

 

Hold them together in the possition to be soldered. Coat liberaly with the flux paste. With a low flame-heat up the parts slowly. The flux paste water will boil off,leaving a white layer. Continue heating up-adding flux to cover the parts,when the flux is clear,you are near soldering temp.

 

Try this out on prctice parts until you can heat up the copper with flux,and getting it up to heat without causing oxidation on the copper,only clear flux is what you are working to have all over the parts to be soldered.

 

Then when up to temp,just touch the patrs with the silver solder wire,that has been dipped in flux,and the parts should melt the solder.

 

Be sure to use gas welding glasses,so that you can see what you are doing in the intence light of the torch. Practise ,practice,practice-you will only get the right combination from doing it until it is natural for you. Try to get someone who knows just how to do it,to teach you and show you wnat is right and wrong.

 

Keith

[Modeler12]

I agree with Mark. It could be the solder. 

I have used 'Solder-it' for lots of brass and copper joints and after some practice had no problems like you describe.

For more details go to http://modelshipworld.com/index.php/topic/1888-silver-soldering-tools/page-2

 

Edited February 8, 2015 by Modeler12

[jud]

I have done some brazing using flux, brazing rod with my oxy-acetoline torch and have been wondering if brazing might be an option for modlers who use the small high heat torchs. Heck you can even weld steel and iron using a torch and wire, don't need flux, the flame will keep the surface from oxidizing if at the right heat.

jud

[captainbob]

If as you say the wire is not melting on the copper it sounds as though the copper is wicking away the heat too fast.

 

Bob

[figuerres]

could it be as simple as the torch is at a good temp to solder brass but just not high enough temp to solder copper ? if it was say 100 or 200 degrees low then it fails to work.

 

I saw the poster say the torch has a possible range that is hot enough but *IS* it actually getting to the right temp ?

[VinceMcCullough]

I suspect that you have two problems. First, I've tried the type of solder that you are using, and also had problems with it. It seems to have a much higher melting point than the silver solders (ranging from "extra easy" to "medium"). That in itself is probably only part of the problem. The other is that copper is a VERY good conductor of heat, which is why ReverWare pans have copper bottoms. They distribute heat evenly over the pan. So I suspect that the copper is wicking the hear away too quickly for the solder to melt.

 

Personally I would stick with silver solder. If you use the paste, you can put minute amoumts of paste on the tube, so that it does not spread out much.

 

Vince McCullough

[rtropp]

I tried to use silver solder with flux (wire) and it did not melt.  I thought that the copper might  be the problem so I just held the wire solder in a tweezer and put flame to it.  It did not melt. 

Just to be sure before I continue my efforts, I sent the torch to Blaze to have it's operation checked. I probably is skill rather than equipment, but before I use up more supplies I thought I should make sure.

 

If the copper is wicking the heat away, how would I work around that.  Most of my work will be with copper.

 

Thanks for the help,

Richard 

[grsjax]

If you can find some fire brick or silica tiles, the kind that are used for very high temp insulation, you can make a small heat trap for your soldering  operations.  Puting the brick or tile around the piece being soldered helps to both keep the heat from wicking away and reflects the heat back on to the work piece.  A base and 3 sides works very well, no need to make a cover.

[dgbot]

If you are silver soldering you make flakes out of the wire and then add them and Flux to the joint this should work.

David B

[rtropp]

grsjax,

had not thought of that.  I will give it a try as soon as I get my torch back.

 

David,

I bought some flakes and tried them but they were really tiny and difficult to place.  I will try shaving some off a silver solder wire and using that.

 

Thanks,

Richard

[rtropp]

Hi all,

After the problems discussed above, I sent the Blazer butane torch back to the manufacturer for them to test.  They report melting 700 F degree solder but that is the highest temperature solder they had for testing. 

 

I had enclosed a sample of the f silver solder which has a melting point of 1300F.  They reported that the torch could not melt that solder.  They also do not have the tools to measure the actual output.    Given that the torch is rated to 2500F I was left puzzled. 

 

They could not refund since I bought it through amazon, and its over a month so I cannot return it.  Actually, the torch is probably less than the cost of materials I went through trying to make it work.

 

So, it does not matter what I do, the torch does not seem to be able to get even close to its rated temperature.

 

I am wondering if anyone has had a similar or different experience with the Blazer and whether anyone knows of a butane torch that will melt high temperature solder and has the fine flame used for small parts? I do not do enough soldering to justify the more expensive torches that use tanks so would appreciate any suggestions.

 

Thanks all for your help,

Richard

[jud]

Thanks for the follow up Richard, I was wondering what you would discover. Can't help you with a torch, I use an acetylene torch for cutting and brazing with large tanks. Have a small brazing tip but not small enough for your job. I have seen those hobby size torches that use bottled gas, expensive but look like useful torches, probably need different size tips for them, but you could braze if needed or heat small pieces of steel for forging or bending.

jud

Edited March 13, 2015 by jud

[bhermann]

Richard - I use this Berzomatic torch for silver soldering.  It runs on butane and is hot enough for the silver soldering I have done to date.  I use the silver soldering paste with flux premixed.  The torch has an adjustable flame.  I picked this up at Home Depot a couple or three years ago and it has been fine for me.  If I am not careful, it is capable of melting and evaporating the brass pieces I am working on.

 

 

Bob

[hornet]

I have a torch similar to Bob's. I have been using a product called Harris Staybrite Silver Solder - liquid flux and wire solder. I have successfully soldered copper strips, brass wire and tube together to make gudgeons and pintels and a variety of other brackets. I am not an experienced solderer by any means but I haven't had a failure yet. The whole lot came as a set at my local electronics store and was only around $50.

 

Edited March 13, 2015 by hornet

[dgbot]

I use a Smith's Little Torch which is a jewelers torch.  Bought it at the NRG conference in Chicago from SEP Tools.  

David B

[rtropp]

All,

Thanks for the information, it has given me a lot of options to look at.

 

Richard

[rtropp]

Bob,

what is the melting temperature of the solder you use?

 

Thanks,

Richard

[bhermann]

Bob,

what is the melting temperature of the solder you use?

 

Thanks,

Richard

Richard - the supplier (SRA) reports the melting point at 1205 degrees Fahrenheit.  The product is described as "Solder Paste with Flux Silver Easy"  There is a medium version that melts at 1325 and a hard that melts at 1435.

 

Bob

[rtropp]

those are approximately the temperatures of the solder I was trying.  I guess the blazer just doesn't reach the temperature it advertises.  One of the members of my ship club loaned by a torch that used oxygen and fuel. I am going to give it a try.  Then, I may just try the Bernzomatic which should be easily available from one of the hardware stores in town.

Bob, does yours still have a model number on it to help with the search?

 

Thanks all,

Richard

[figuerres]

Interesting to hear that my hunch was right, they sell it has 2500 but have no way to test it for that ?  sounds like I will not buy from them. if you have that data in writing I would ask them to send you some money.

they advertised / packaged the device with a claim that they could not test and failed to back up.

regardless of where you bought it they sold a defective device that they manufacture and you proved the defect in a very reasonable time.

 

did you get the info in writing ?  get it!

 

amazon or your CC company should get you the purchase cost at the least.

yeah it's not a lot but the point is they are full of bs and I would advise amazon of the false claim they make and they should pull the product.