Anyone here experienced in silver soldering?

[Hannibal]

Doing some practice since this is new to me. I have no trouble with brazing steel or soldering copper, even soldering electrical components but I'm apparently doing something wrong now.

I'm wondering if there's an issue with the solder itself. I'd appreciate any advice someone with hands - on experience can provide.

Thanks for looking.

[Hossfly]

What are you trying to solder?

[Recycled bullet]

Clean the the connecting joint you intend to solder with sandpaper then apply flux to the parts and put some flux on the solder wire heat up the base pieces with the torch and the metal will flow into the joint. You can use water to freeze the joint. I use an old brick as an insulator. Was making little robot men out of cut up coat hangers, 6.5 Creedmoor brass, pieces of copper wire and 10 mm bolts.

[Hannibal]

What are you trying to solder?

I have a couple of projects in the works. In both cases I'm attempting to solder fairly large pieces of steel.
I've cleaned everything well, scuffed the surfaces with scotchbrite and cleaned again. Applied Flux. Plenty of heat but the solder continues to ball up and roll off as if the surfaces are dirty.

Pretty frustrating.

Solder is about 10 years old but has been stored in a clean, dry cabinet in a temperature controlled environment.

First time I used it it worked beautifully. Second time not nearly as well but I thought perhaps I wasn't holding my mouth right or something. This time it won't flow at all.

[Hossfly]

Mtrl has to be clean, you can use sandpaper for smooth surfaces but wire brush works to get into small areas to clean real good. And as said must flux well and watch for color change to apply either 45% or %55% silver. You can buy prefluxed solder also blue or orange color.

[Hossfly]

What % silver is the solder?

[country gent]

You dont state the problem your having.
electrical and copper pipe are soft soldering process at around 500* with a flux. Brazing and silver solder are hard soldering at higher temps 1500* and a stronger flux.
Silver solder with black flux needs to get hot to melt and flow. I clean the parts then clean again and flux, lay a piece of solder in the flux and lay the top piece on depending on part I clamp with a third hand jig or clamp with a clamp. I then heat with oxy acetylene and watch for the part to settle and solder to flow. Then allow to cool on its own.

the soft solder flux stays soft and can be wiped off the hard solder flux becomes hard and glass like when it cools.

Like brazing or other heat in the direction you want the solder to flow it will follow the heat. Just like when soldering a copper pipe when its clean well fluxed and up to heat you touch the solder to the joint and its zip all around and to depth. When you get to temp with the silver solder the parts sits down and theres flow all around under the flux.

[M-Tecs]

What silver solder are you using and what's your heat source?

[Hossfly]

Sounds like your solder is melting before the steel is getting hot.

[Recycled bullet]

Yeah if the solder is not wetting to the base material then the base material is still cold.

[Hannibal]

Yeah if the solder is not wetting to the base material then the base material is still cold.

It's glowing medium orange before applying solder. Balls up and rolls off. No flow at all.

[country gent]

If the solder is balling up then your material is to cold. It takes a lot to get big pieces hot enough the mass pulls the heat way.

I normally use 45% silver to attack carbide to cutter shanks. A 1/2" or 5/8 shank 3-4" long takes a lot of heat before the solder flows.

On big jobs I have seen 2 guiys working the joint one preheating along the joint and the second following with the torch and doing the soldering.

WIth the solder balling it sounds like improper flux or to cool

[country gent]

Also avoid an oxidizing flame

[Hannibal]

What silver solder are you using and what's your heat source?

Prest-O-Lite torch. Large tip. BenzOmatic silver bearing acid core flux solder. Solder worked perfectly in the past but it's been 10 years since I bought it.

[Hossfly]

If you’re using flux you may be burning it away before solder is melting. It’s a fine art to some soldering.

[Hannibal]

Also avoid an oxidizing flame

Tried that too.

[Hannibal]

If you’re using flux you may be burning it away before solder is melting. It’s a fine art to some soldering.

Agreed but something has changed. I used this same roll of solder before and it never acted like this.

[country gent]

Bring the material up to a dull red then touch the solder to the material just ahead of the torch flame right at the forward edge of the flame

[Hannibal]

Bring the material up to a dull red then touch the solder to the material just ahead of the torch flame right at the forward edge of the flame

That's when it balls up and rolls off like butter on a hot skillet.

[M-Tecs]

Again, what silver solder are you using and what's your heat source? If it's an oxy acetylene flame you want neutral or slightly carburizing. An oxidizing flame will prevent proper wicking.

[country gent]

Did you try cleaning the solder pull a length thru a clean scratch pad a few times.

[Hannibal]

Again, what silver solder are you using and what's your heat source? If it's an oxy acetylene flame you want neutral or slightly carburizing. An oxidizing flame will prevent proper wicking.

Look at post #14. I answered your questions.

[Hannibal]

Did you try cleaning the solder pull a length thru a clean scratch pad a few times.

No, I did not try that. I did cut about 2" off the end before I started.

[country gent]

any oxidation in the process is dooming. it over time the solder may have oxidized it should be bright and shiny not a dull grey. All materials needs to be clean.Best is new solder flux and fresh cut materials sanding or grinding is next then come wire brushes.
When I have to solder copper tubing its 60 grit emery to clean not the wire brushes. brighten the end and inside flux heat and apply solder its a quick zip as the solder flows and fills.

Another is you have to have "room" in the joint for the solder. like glue you can have to tight of a joint for it

[Hannibal]

any oxidation in the process is dooming. it over time the solder may have oxidized it should be bright and shiny not a dull grey. All materials needs to be clean.Best is new solder flux and fresh cut materials sanding or grinding is next then come wire brushes.
When I have to solder copper tubing its 60 grit emery to clean not the wire brushes. brighten the end and inside flux heat and apply solder its a quick zip as the solder flows and fills.

Another is you have to have "room" in the joint for the solder. like glue you can have to tight of a joint for it

I appreciate your advice. I'm a bit aggravated right now so I'll think about it and try again tomorrow. So far as appearance the solder looks very clean, not gray. Usually I have no trouble at all so I'm considering causes that I normally wouldn't. Perhaps the flux and the solder aren't compatible? IDK.

[Martin Luber]

Same problems here. The original flux dried up to a hard crust. I cant redisolve it with anything

What should I use for flux…even tried boraxo soap

[Hannibal]

Same problems here. The original flux dried up to a hard crust. I cant redisolve it with anything

What should I use for flux…even tried boraxo soap

Hopefully someone has a good suggestion. Right now I've no good ideas. Appears we are in the same boat.

[Hossfly]

I use the white flux in plastic bottle and reconstitute it with water. Think it’s called sta silv.

[Hannibal]

I use the white flux in plastic bottle and reconstitute it with water. Think it’s called sta silv.

Found that on line. Any particular solder you like? I think for starters I'm just going to try a new combination and avoid acid core this time. I presume things like acid core solder have a shelf life but right now that's just a guess.

[Winger Ed.]

I've had good luck with the American made Sil-Fos brand.
The sticks imported from China always gave me fits.

They make it in different amounts of Silver content.
The more Silver content, the easier it is to work with..... and a little more expensive.
I think it was either 15 or 20 that I used in years past.

It comes in a stick that looks like a coat hanger wire hammered out flat and about 18 inches or so long.
A good hardware store should have it on the shelf.

[DougGuy]

I silver solder torch heads on tubes, stainless tubes and stainless torch head. Metal is very clean, sanded shiny, I am using either Harris stay silv or Sua white flux No.1

Solder is 56% silver, it has a high melting point which makes it perfect for soldering cutting torch heads on tubes. Brush the flux in the holes and on the tubes then stick the parts together, clamp them for no movement this is critical. I get the metal a good cherry red/orange pull the flame off and stick the solder on where I want the solder to flow, give it a few seconds for the solder to heat up and if it doesn't break and wet the joint, pull it off and heat some more, when it's hot enough it will melt and flow like butter. It is a silvery bronze color on the spool and finishes really pretty like gold.

I use a No. 3 tip oxy/acetylene. Sounds like you don't have enough heat or enough in the right place and I have never used that solder, I have used 15% soldering copper nickel, 45% is a good strong solder and it's easy to work with, use oxy/acetylene it puts intense heat in small places near the weld, lesser torches have to heat too much of the surrounding area.

[M-Tecs]

The Harris Stay-Silv White Paste Brazing Flux doesn't go bad but it does need water to reconstitute if it dries out. I've silver solder hundreds possibly thousands of parts with silver solder. That has always been done with oxy/acetylene torch or a heat treat oven.

Never used an air/acetylene torch or acid core silver solder so I have no firsthand experience with most of what you are using.

[Hannibal]

I silver solder torch heads on tubes, stainless tubes and stainless torch head. Metal is very clean, sanded shiny, I am using either Harris stay silv or Sua white flux No.1

Solder is 56% silver, it has a high melting point which makes it perfect for soldering cutting torch heads on tubes. Brush the flux in the holes and on the tubes then stick the parts together, clamp them for no movement this is critical. I get the metal a good cherry red/orange pull the flame off and stick the solder on where I want the solder to flow, give it a few seconds for the solder to heat up and if it doesn't break and wet the joint, pull it off and heat some more, when it's hot enough it will melt and flow like butter. It is a silvery bronze color on the spool and finishes really pretty like gold.

I use a No. 3 tip oxy/acetylene. Sounds like you don't have enough heat or enough in the right place and I have never used that solder, I have used 15% soldering copper nickel, 45% is a good strong solder and it's easy to work with, use oxy/acetylene it puts intense heat in small places near the weld, lesser torches have to heat too much of the surrounding area.

Well I'm certain heat isn't the problem as it melts immediately when touched to the parts. I am trying to solder mild steels together and I'm not sure if I need a different alloy for that. Again, what confuses me is I've used this in the past and it worked great. So something has changed apparently but I've no idea what.

I'm in the process of trying to determine what alloy is the best fit for my use and what flux I need. I definitely want to avoid acid core going forward. May or may not be the problem, just trying to eliminate future problems.

Right now the solder I have is behaving as if the parts aren't clean or are oil contaminated. But I'm certain that isn't the case.

[country gent]

Both the sta silver white and the black can be reconstituted with water its a job takes awhile to soak in then break the chunks up and add water to a thick paste. I have ran a drill bit into the hardened mass to break it up then add the water.

Silver solder like braising rod has the flux in a dry coat on the out side. Flux core and acid rosin all denote a lead tin solder or low temp. On your roll of solder whats the designation? 30-70, 60-40, 45%, 55%. The last 45 silver solder I bought was almost $80.00 an ounce. Silver solder is almost like a spring wire very stiff. Lead tin is soft and easily bendable. Silver solder is a small dia 1/16" or so soft solder is a bigger dia. Silver solder also has a goldish tint.

[DougGuy]

Well I'm certain heat isn't the problem as it melts immediately when touched to the parts. I am trying to solder mild steels together and I'm not sure if I need a different alloy for that. Again, what confuses me is I've used this in the past and it worked great. So something has changed apparently but I've no idea what.

I'm in the process of trying to determine what alloy is the best fit for my use and what flux I need. I definitely want to avoid acid core going forward. May or may not be the problem, just trying to eliminate future problems.

Right now the solder I have is behaving as if the parts aren't clean or are oil contaminated. But I'm certain that isn't the case.

Get some stick solder no flux, use white flux in the jar. Alloy depends on how high a temp you want the steel to tolerate. Generally the lower the % of silver the lower the melting temp for the solder and the less strength it will have, but sounds like you have acid core soft solder which is ehh ho hum for what you are wanting to do with it. Not very strong up against hard solder.

[Hannibal]

Both the sta silver white and the black can be reconstituted with water its a job takes awhile to soak in then break the chunks up and add water to a thick paste. I have ran a drill bit into the hardened mass to break it up then add the water.

Silver solder like braising rod has the flux in a dry coat on the out side. Flux core and acid rosin all denote a lead tin solder or low temp. On your roll of solder whats the designation? 30-70, 60-40, 45%, 55%. The last 45 silver solder I bought was almost $80.00 an ounce. Silver solder is almost like a spring wire very stiff. Lead tin is soft and easily bendable. Silver solder is a small dia 1/16" or so soft solder is a bigger dia. Silver solder also has a goldish tint.

Well this stuff is on a small roll and unfortunately does not list the content on the label. It's pretty soft/malleable and is .062" in diameter. Bernzommatic SAC300. Checked online and can't find any information on content there, either. I think I'll just toss this and start over.

[Hannibal]

So. I'm unable to determine the content of the solder I have so I'm going to dispose of it and start over.

For those of you who understand silver soldering, what would you choose to solder 1/4" mild steel together? There are a pair of pins internal to aid locations and it's a tight joint. Also would appreciate a flux recommendation.

[farmbif]

if you wanting to join large pieces of steel why do you want to silver solder it? ive always believed that the 5 and 15 silver solder rods like are used in HVAC are for bronze, brass and copper joints or joining any of those materials together and when joining steel, like hydraulic joints or gun sights 45-55% silver solder is needed. the silver solder is very expensive. but I went to welding/metal fab school almost 50 years ago and maybe things have changed with new materials and such.
why not braze or weld the large pieces of steel together?

[Rockindaddy]

There is no such thing as acid core silver solder or silver braze. You must be using a lead/ tin base acid core solder that melts around 650* Silver braze requires an oxygen-acetylene torch and melts at 1500* The flux is white and looks like dry wall compound. Been silver brazing since I was a kid 60 years ago. Its easy! Silver braze solder wire is just shy of $95 per small roll. Only tiny parts can be silver brazed with a propane torch. Go see your local welding supply shop They will know what you are doing wrong.

[country gent]

what is the physical size of the joint length and width in inches

[M-Tecs]

Prest-O-Lite torch. Large tip. BenzOmatic silver bearing acid core flux solder. Solder worked perfectly in the past but it's been 10 years since I bought it.

That is less than 1% silver. https://db1736767dbd5e7094bb-d61bbc5d0b342a54145a236e2d5d1ebf.ssl.cf4.rackcdn.c om/Product/0314bb65-7bfe-41dc-af67-78c56171125c.pdf

[farmbif]

there are eutectic, or there used to be, solders available for joining steel and stainless steel. I still have a couple large spools of the stuff that will join stainless. it works great for putting stuff like commercial kitchen hoods and such together but not as strong a joint as mig, big or stick.

[Hannibal]

There is no such thing as acid core silver solder or silver braze. You must be using a lead/ tin base acid core solder that melts around 650* Silver braze requires an oxygen-acetylene torch and melts at 1500* The flux is white and looks like dry wall compound. Been silver brazing since I was a kid 60 years ago. Its easy! Silver braze solder wire is just shy of $95 per small roll. Only tiny parts can be silver brazed with a propane torch. Go see your local welding supply shop They will know what you are doing wrong.

Can't argue. Just reading the label and I've not used silver solder before buying this product.

[JustinP]

It's either joint contamination or not enough flux.
My guess is it's a flux issue.
But I did wonder if your scotch-brite pad was contaminated with oil or something which in turn would contaminate your joint.

[Hannibal]

That is less than 1% silver. https://db1736767dbd5e7094bb-d61bbc5d0b342a54145a236e2d5d1ebf.ssl.cf4.rackcdn.c om/Product/0314bb65-7bfe-41dc-af67-78c56171125c.pdf

Very well might be. I can't find any content listed on the spool and I can't find anything listed online regarding content.

[Hannibal]

New pad and I cleaned it with acetone before applying heat so I can't fathom how. I agree it sure acts like it though.

[Hannibal]

what is the physical size of the joint length and width in inches

The base piece is 1 7/8" x 5". The part I'm attempting to attach is 1 7/8" x 7/8". Along one end of the base piece is where I'm attaching it. So the joint is essentially 7/8" x 1 7/8".

[country gent]

being 1/4" mild steel and pins for alignment I think I would opt for a tig weld with pre heat of the material. A good brazed joint will work. silver solder would be way down on my list do to the amount of solder and cost.

A lot of our silver soldering on bigger tools we would pre heat on a piece of carbon or aluminum in the furnace clamped together to temp then pull them out and touch the solder to them. You got a beautiful joint good penetration/flow and little warpage.

On medium to big parts a plain propane or map gas torch is going to be wanting getting up to temps required.

1/4" can easily be veed out and welded With the right filler rod when cleaned up the weld will disappear. A good tig weld will have almost no splatter and the pattern or grain will polish out quickly.

I normally braze cast iron in bigger jobs, steels aluminums stainless tig or mig. I reserve silver solder for little jobs or attaching carbide cutters to shanks. soft solder is for electricals and plumbing.

[M-Tecs]

The base piece is 1 7/8" x 5". The part I'm attempting to attach is 1 7/8" x 7/8". Along one end of the base piece is where I'm attaching it. So the joint is essentially 7/8" x 1 7/8".

Regardless of silver braze you are using you want .002" to .005" clearance for maximum strength and wicking. For larger areas like you have light prick punch marks work well or silver braze foil/sheet. Never used this one but this is an example of the product. You would cut a 7/8" x 1 7/8" piece and sandwich it in between the pieces with flux.

https://www.amazon.com/Silver-Brazing-Soldering-Welding-Material/dp/B07S67TWKP?th=1

https://www.canadametal.com/wp-content/uploads/2016/08/brazing-silver-alloy.pdf

[Hannibal]

being 1/4" mild steel and pins for alignment I think I would opt for a tig weld with pre heat of the material. A good brazed joint will work. silver solder would be way down on my list do to the amount of solder and cost.

A lot of our silver soldering on bigger tools we would pre heat on a piece of carbon or aluminum in the furnace clamped together to temp then pull them out and touch the solder to them. You got a beautiful joint good penetration/flow and little warpage.

On medium to big parts a plain propane or map gas torch is going to be wanting getting up to temps required.

1/4" can easily be veed out and welded With the right filler rod when cleaned up the weld will disappear. A good tig weld will have almost no splatter and the pattern or grain will polish out quickly.

I normally braze cast iron in bigger jobs, steels aluminums stainless tig or mig. I reserve silver solder for little jobs or attaching carbide cutters to shanks. soft solder is for electricals and plumbing.

Going to send you a PM and disclose more details.

[country gent]

How about 2 or 3 flat head screws 1/4 20 drilled thru one and tapped into the other. with the pins that will be as strong or stronger than the solder joint. Easier too.
clamp on the pins lay out the holes center punch drill a #7 hole separate open one side to letter f or g countersink and bolt together.

[country gent]

Will be awaiting your PM

[elmacgyver0]

Soldering can be a bit of an art form.
I used some of that soft silver bearing solder to solder two stainless steel mixing bowls together to form a large spherical still.
I tried using a torch and the solder just balled up like you described.
I finally got it to work using a heavy antique coper soldering iron, who would have thought?
I did use a liquid flux and heated the iron with a torch, it does not take that much heat for the soft silver solder, it does take finesse.
You have to use the iron to smear the solder on the part kind of like frosting a cake, once you get both parts wetted with solder you can put them together and heat them to get them to join.
Of course, this won't work with the hard silver solder, that takes a lot of heat, like brass brazing.

[farmbif]

I would not call that "silver bearing lead free solder" silver solder. I believe that acid core stuff is made for plumbing and maybe stained glass windows, rosin core would be for electrical wires/electronics. silver solder is used for specialized stuff for the most part. HVAC, hydraulics, gun sights, carbide and tungsten joints, ect

[Hannibal]

Will be awaiting your PM

Forum says your inbox is full. Odd because I couldn't send anything yesterday because mine was supposedly too full. Forum issue perhaps.

[Hannibal]

I would not call that "silver bearing lead free solder" silver solder. I believe that acid core stuff is made for plumbing and maybe stained glass windows, rosin core would be for electrical wires/electronics. silver solder is used for specialized stuff for the most part. HVAC, hydraulics, gun sights, carbide and tungsten joints, ect

Very possible. I bought it several years ago and thought I had the right stuff. Beginning to look like that was my first mistake which has compounded with time.

[country gent]

I should be opened up now. Did you receive my PM a little while ago?

[Hannibal]

I should be opened up now. Did you receive my PM a little while ago?
No Sir. I'll try to PM you again.

[country gent]

Ill see if I can find it and resend it.

[Hannibal]

Ill see if I can find it and resend it.

Just messaged you. Looks like it worked this time.

[ulav8r]

1% silver bearing solder has a much lower melting point than Sil-Phos or true silver solders. 430 degrees vs. 1200 degrees or more. The flux included with silver bearing solder will burn at much higher temps and will create a "dirty" surface that solder will not stick to.

[elmacgyver0]

I would not call that "silver bearing lead free solder" silver solder. I believe that acid core stuff is made for plumbing and maybe stained glass windows, rosin core would be for electrical wires/electronics. silver solder is used for specialized stuff for the most part. HVAC, hydraulics, gun sights, carbide and tungsten joints, ect

The silver solder I'm familiar with is a solid wire that is not very flexible, more like music wire.
The "silver bearing solder" is something else, it does have a small percentage of silver.
I have used the hard silver solder to attach extensions on short gun barrels to bring them to legal 16+ inch length when building semi-auto versions of sub guns to conform with ATF regulations.

[elmacgyver0]

1% silver bearing solder has a much lower melting point than Sil-Phos or true silver solders. 430 degrees vs. 1200 degrees or more. The flux included with silver bearing solder will burn at much higher temps and will create a "dirty" surface that solder will not stick to.

This!

[country gent]

when I put together a cutter carbide on a steel shank I have freshly milled stoned surfaces. I then soak them in a 50 50 mix of white vinegar and hydrogen peroxide several hors or over night. this etches the surface to a nice surface. flux and lay silver solder in flux and assemble with a "third hand" holding them on the welding table. I normally use a #3 tip on the oxy acetylene torch When it hits temp I see the solder flow around the seam joint. the part then sits under the third hand until cooled down. Its then ready to soak and wire brush to remove the glass like flux grind and use.

[Hannibal]

when I put together a cutter carbide on a steel shank I have freshly milled stoned surfaces. I then soak them in a 50 50 mix of white vinegar and hydrogen peroxide several hors or over night. this etches the surface to a nice surface. flux and lay silver solder in flux and assemble with a "third hand" holding them on the welding table. I normally use a #3 tip on the oxy acetylene torch When it hits temp I see the solder flow around the seam joint. the part then sits under the third hand until cooled down. Its then ready to soak and wire brush to remove the glass like flux grind and use.

Thanks for the benefit of your experience. Good stuff!

[Hossfly]

Found that on line. Any particular solder you like? I think for starters I'm just going to try a new combination and avoid acid core this time. I presume things like acid core solder have a shelf life but right now that's just a guess.

Harris is what I’ve used.

[Hossfly]

You’re on the right track with what the guys are telling you about using the 45%-55% wire silver solder.
With the white flux, comes in plastic bottle and is a paste, it dont go bad, it will dry up but you just add a little water, comes with brush inside. Solder is sold 1 Troy oz. Plastic container rolled, not cheap. Joint has to be very clean, new wire brush clean flux and play torch appropriately to size of job. Oxy. Acct. works best with proper tip. Flux will turn amber color and start to flow then add small amt of your solder.
It is tricky but gets better with practice.

[Hannibal]

The flux included with silver bearing solder will burn at much higher temps and will create a "dirty" surface that solder will not stick to.

After sleeping on it and now that I realize what I have I suspect this is exactly what is happening.

[.429&H110]

I learned refrigeration in trade school.
You have a community college that might let you audit a class and see all the ways and ways of magic.

Taught me to bend and swedge copper, all sizes, rarely use a fitting. Fittings cost money, look bad.
Drop a silver ring in the fitting first, heat until the silver shows. Quick and minimum silver.
If you see a someone soldering refrigeration without a nitrogen purge your job is doomed.
Copper oxidizes on the inside to sandpaper grit, water plumbing washes it out
but in a sealed system you will have grit lubricating the compressor.
Compressors don't die, techs kill them.

It's a big subject.

[Hannibal]

I learned refrigeration in trade school.
You have a community college that might let you audit a class and see all the ways and ways of magic.

Taught me to bend and swedge copper, all sizes, rarely use a fitting. Fittings cost money, look bad.
Drop a silver ring in the fitting first, heat until the silver shows. Quick and minimum silver.
If you see a someone soldering refrigeration without a nitrogen purge your job is doomed.
Copper oxidizes on the inside to sandpaper grit, water plumbing washes it out
but in a sealed system you will have grit lubricating the compressor.
Compressors don't die, techs kill them.

It's a big subject.

I appreciate your advice. I'm actually attempting to solder mild steels together. Same basic principles apply however given the solder I had on hand I think my mistake was actually too much heat. Causing the flux to burn and creating a contamination problem.

I appreciate everyone's posts and advice. I've ordered a 45% silver alloy solder and a different flux. Hopefully this will work well with my project.

[Hannibal]

So to follow up, I re-cleaned the pieces and tried again using a much smaller tip and it worked perfectly. Apparently when I'd used it before I wasn't applying nearly as much heat so that was the problem.

I still want a stronger joint so I'll be doing more testing in the future once the 45% solder and flux arrives but at least now I understand what was causing me problems this time.

Thanks for all the replies. Lots of good information in this thread. I've learned a lot and I'm always amazed at the knowledge of this forum's members.

[.429&H110]

From a copper to copper point of view I really don't like phos copper.
Phos works fine, once, but it's a one shot one try then the phos is gone.
Phos is certainly not for repair work. Phos is cheap the Chinese love it.
And the Chinese are apt to have lead in their brass faucets.
1% Lead fills a brass mold better, cheaper, will make a water sample flunk a lead test.

Another subject that will kill you is Cadmium.
Long ago we used Cadmium solder, and Cadmium is still out there.
That is why we keep the wind at our back, face shield and eye protection.
Eye doctor told me you can get UV from a gas flame, when I got my cataracts out.
Now you tell me.

[.429&H110]

Long ago in NH story?
I tended an old 120hp Cleaver-Brooks boiler, brushed it, talked to it, set up it's variable firing rate 10-30gph. It's flue efficiency was amazing 90-95%, would almost condense flue gas, too bad that it made NOx, firetube, hydronic ran 230F flooded, heated offices, a gym and locker rooms, made enough domestic hot water to shower two hockey teams at once, looked like a locomotive and about as noisy.

It went into alarm one cold Saturday, the air pump had destroyed itself.
Primary air pump is a block of cast iron with a five inch cylinder bored through, five vanes spin offset pumping air, with motor oil oozing in. Two of the vanes broke and went round and round digging big chunks out of the cast iron, good thing the flame failure worked.

Dismounted the thing got on the phone was not a replacement anywhere best idea was to use compressed air?
Only 20psi, but a lot of CFM. Need a solenoid. Doable.
Old Guido was on campus doing trash wanted to know "Don't they teach you kids nothin in trade school?"

So Guido let me hold the rosebud, once the cast iron was 1000F? not quite glowing Guido started laying in silver solder. It was an ugly gobbery mess, but a cylinder hone polished it bright and round. I had it rehung before it was cool to touch, oil heat back on sooner than boss expected. Why the casting did not crack, I do not know. Heated slowly? Guido is long gone, and I miss the Guidos we have lost.