Silver soldering.......a newbe to boilers

[Rocket Man]

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[Rocket Man]

Now I remember why I upload this picture. My cooling system is 88 ft of 1/4" copper tubing 42 turns it can turn 3800 volumes on stream to 1 quart of water in 1 hour. Boiler will boil away 1 quart of water in 1 hour. This is a good way to test your boiler to see how much steam it makes. I can use this cooling system to test any boiler that will boil 1 quart of less water per hr. The goal is to collect all the steam the boiler makes turn it to water and measure it. If you know how many volumes of steam your boiler makes do the math to determine RPMs your engine will run. You may already know this I just figured it out on my own. To be 100% accurate you need to save engine exhaust steam and turn it to water so you know how much steam an engine needs to run and how much steam boiler needs to make.

 

[Rocket Man]

How do I delete a loaded picture? I clicked email message to get here why is this not the thread I started.

 

[awake]

Rocket Man, the thumbnails can be clicked to see the larger picture.

By the way, this is what we, here in rural North Carolina, call a "still life" picture.

 

[goldstar31]

Do old UK Silver florins( 92.5% pure silver) work as silver solder?

Last time that I asked about such interesting things was that I have a small quantity of used scrap silver amalgam.

Waste not, want not

 

[awake]

Norman, it can be done, but it does require some special processing. I happen to be able to do that processing, but it does take a considerable amount of time to complete. All that to say, if you send me the silver, I will get the solder back to you in, say, 15-20 years. No thanks necessary; I am happy to do this.

 

[goldstar31]

I also have some dental gold which, as awake will know, will not assay because it contains platinum

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[I make chips]

In business I've designed and sold many brazing systems for production. One of the vendors I used for alloy selection is in this link. Click on the videos for some good education. https://www.icscuttingtools.com/catalog/page_316.pdf

For general silver brazing I'd go with a 45% silver. It flows nicely and can be used in tight fitting joints. IIRC the melt temp is 1280F. 693C. Yes, remelt temperatures are much higher. I could rattle on for hours on tech details but by bringing up the alloy supplier websites will shorten the learning curve. In the states, Bellman Melcor, Lucas Millhaupt and others have good data that's easily accessible.

 

[jwills8606]

I had been soldering with silver-solder substitutes for years, and then by chance ordered some high-percentage real silver solder online. It is amazing. One of the first things I did was solder an electrical lead to a piece of chrome-plated steel. I've never seen anything stick to chrome, but it flowed like lead solder on copper. I'm sold.

 

[john futter]

I'm probably telling people how to suck eggs But!!.
I had to teach our mechanical workshop guys how to silver solder. They said silver solder didn't work.
They had things clean enough
They had plenty of the correct flux
they had plenty of heat (oxy Acetylene)
But joints didn't run and leaked.
I observed how they soldered and it was obvious to me what was wrong.
1./ they overheated the joint by applying direct flame to the solder area -- the flame should be near but not direct
2./ The flame on the oxy Actylene was set at neutral not carburising ie long feathers , long cone, this is the most important factor. One must keep oxygen away from the joint so that it tins properly and the silver solder components are not themselves oxidised

 

[I make chips]

Yup, it's a waiting game type of process. You have to go slowly and let the flux melt and coat the alloy. Then the molten flux will melt the alloy and it'll flow nicely.

 

[harborfreight8x12]

I'm probably telling people how to suck eggs But!!.
I had to teach our mechanical workshop guys how to silver solder. They said silver solder didn't work.
They had things clean enough
They had plenty of the correct flux
they had plenty of heat (oxy Acetylene)
But joints didn't run and leaked.
I observed how they soldered and it was obvious to me what was wrong.
1./ they overheated the joint by applying direct flame to the solder area -- the flame should be near but not direct
2./ The flame on the oxy Actylene was set at neutral not carburising ie long feathers , long cone, this is the most important factor. One must keep oxygen away from the joint so that it tins properly and the silver solder components are not themselves oxidised

Hello John. I'm glad you posted this, back many years ago when I was driving 18 wheel transports, I was assigned a truck without a working heater (in the middle of winter). So I drove the truck to the maintenance shop and asked one of the mechanics to re-solder the leaking heater core. He told me he didn't know how to solder. I used to repair auto and truck radiators (back before they were plastic), so I showed him how to clean, tin, and allow solder to flow into the joints. He was speechless. Kind regards, Al

 

[peterl95124]

to the gentleman who suggested that cadmium in silver-solder was safe, please look up the boiling temperature of cadmium, you'll be surprised.

 

[goldstar31]

Dangerous cadmium oxide fumes affecting lungs and liver

 

[John Antliff]

I did emphasise that it should be used with good ventilation (but not draughty) and that our occasional use would not put our bodies in jeopardy.

 

[peterl95124]

The boiling point of Cadmium is 1412-F, the melting point of the most commonly used silver solders are 45-% silver is 1266-F, and 56-% silver is 1205-F. It takes skill and practice to not over heat what you are brazing, and the smaller the part the harder that is to do, I have accidentally melted some small copper and brass parts I was silver-soldering, whose melting points are more like 2000-F, and I was only using propane, not MAPP-gas and not oxy-acetelyne. If you are having trouble getting the solder to "wet" to the part then there's something wrong with your technique, which you should trouble-shoot and fix rather than resort to cadmium. I only have cadmium-free silver in my shop, and strongly urge people to only use cadmium-free. If you have any doubts about cadmium read the wikipedia page on cadmium poisoning.

 

[Cogsy]

The boiling point of Cadmium is 1412-F

This is true of the pure substance, but alloying can significantly change the boiling points of the constituents. I haven't been able to find any detail on whether the boiling point of cadmium increases or decreases when alloyed with silver. Weird things can happen when alloys are made, for instance you would think that a 50:50 alloy of two elements would have a melting point somewhere between the two elements original values, but there are many that have greatly reduced melting points even far below the melting point of any single component. Equally, the new alloy can have a much higher melting point than any of the components. Boiling points can equally be affected.

 

[goldstar31]

From what little I know- and I am a pretty confident and competent silver solderer, once the alloy has melted onto its chosen metal, the melting point of the residual solder 'increasers'. what happens when the temperature goes up sufficient for it to boil, i have never been sufficiently adventurous to find out. I do know that 'professionally', there was a chemist who was separating cadmium out of alloys and- then he wasn't there.
Further back in the history book, my maternal grandfather was a miner who according to demand or the lack of mined coal at one time but also dug out galena from the lead mines and reportedly boiled lead to extract the silver in the soot generated. Most of those employed didn't live long and the other side of my wife's family were connected with 'lead' manufacturing where there is a history of quite horrific damage to workers. It wasn't just Charles Dicken's novels which drew attention to what became known as 'Dickensian ' working conditions endured by children as well as adults.
My thoughts, therefore, make me wonder why on earth, people want to make an issue of practices which are known to kill or main. When I 'did' my City and Guilds in Motor Vehicle Restoration, we conducted things in 'fume cupboards'.
I hope that my thoughts and views reinforce the emphasis of plain simple common sense.
Thank you for reading

 

[peterl95124]

This is true of the pure substance, but alloying can significantly change the boiling points of the constituents.

You won't be able to find out if Cadmium's boiling point increases or decreases in Silver because that's not what happens. For example distilling alcohol from water happens at the boiling point of alcohol, has nothing to do with the boiling point of water, or the boiling point of anything else that you might have alcohol dissolved in. What you are confusing this with is the melting point, which for an alloy is typically, and somewhat counter-intuitively, lower than any of its constituents rather than the average of its constituents. The only way you can change the boiling point of a substance, be it alloyed dissolved or whatever, is to change the pressure, for example you can boil the alcohol out of water at room temperature with a vacuum, similarly you can boil the water out of coffee with a vacuum and that's how most instant coffee is made these days. Theoretically you can prevent Cadmium from boiling at 1412-F by raising the air pressure, for example in a hyperbaric chamber or in a diving bell at the bottom of the ocean, but there might be some technical problems with this !!!

 

[Cogsy]

You won't be able to find out if Cadmium's boiling point increases or decreases in Silver because that's not what happens. For example distilling alcohol from water happens at the boiling point of alcohol, has nothing to do with the boiling point of water, or the boiling point of anything else that you might have alcohol dissolved in.

It's actually a little more complex than what you've explained above. For instance, adding salt to water increases the boiling point of the water. It's all to do with the bonding between the elements in the solution and just like the melting point (which is affected by the same factors) boiling points can be lower or higher than the constituents.

Some alloys can also form azeotropes which means they can't be separated by distillation (even ethanol and water form an azeotrope at a certain mixture point and cannot be further separated by distillation). Interestingly, in your alcohol/water example, the ethanol (drinking alcohol) has a boiling point of about 78.4 C and water at 100C but a water/ethanol mix has a boiling point of about 78.2C. So when distilling spirits, the azeotrope (around 96% alcohol and 4% water) boils out at lower temperature than either constituent on its own could. The azeotropic behaviour can go in both directions depending on the constituents, which means the boiling point of some substances can be (sometimes significantly) higher than any of the components.

Again, I don't know what the effect is on the boiling point of cadmium in a silver alloy!