Can someone explain this soldering phenomenon?

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Finch85

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I had to redo this particular fitting 4 times. A couple months back, my soldering went well especially given the fact it was my first time. Not so lucky this time. Here goes.

I was having trouble with a 1/2" x 1/2" female adapter (copper to pex). It doesn't leak now but the joint still looks iffy.. A small section of the fitting directly facing me doesn't appear to take solder. The copper pipe was cleaned and fluxed. The fitting was cleaned and fluxed. When it would leak, I'd have to de-solder to remove. Upon inspecting the 3 fittings that didn't take, I could see a section inside the fitting that didn't take any solder. You can also tell this on the front of the fitting too. The last one I just did looks the same in the front (no solder) but I have no leaks so I guess it took inside.

I don't know what to do. I even bought a new brush to clean inside the fitting better but my other one was pretty much new. Should I redo this fitting even though there are no leaks? I'm thinking yes but sometimes I don't leave well enough alone. Maybe its my technique...I heat the joint until it begins smoking, then I reach around the backside to solder first and then I bring it around to the front.
 
if it's smoking, there is burning flux. burning flux will make the solder not take very well. i, not being a plumber but an avid handyman of sorts watch for the flux to slightly bubble, then try to apply solder. if it won't take, play the flame around the fitting another little bit, then try again. smoke=burnt flux=not good from my experience.
 
You know...you might be onto something there. When I first soldered a couple months ago, I was inexperienced (still am obviously) but was trying the melt the solder too soon and then I'd finally hit it at the right time.

Today, I was waiting a good 15 seconds before even attempting touching the solder to the fitting.
 
if it's not leaking, i personally would leave it alone. it holds all the pressure in the line. if it was going to leak, i think it already would have. i have had one line where it was a slow drip, one or two a day. hard to catch. i eventually redid that one. keep an eye on it for a day or so, if no leaks, leave it alone. :)
 
Chad Schloss said:
if it's not leaking, i personally would leave it alone. it holds all the pressure in the line. if it was going to leak, i think it already would have. i have had one line where it was a slow drip, one or two a day. hard to catch. i eventually redid that one. keep an eye on it for a day or so, if no leaks, leave it alone. :)
Click to expand...

I don't know if I'll be able to do that. :) Especially since my technique may have been off. I'll sleep on it. I'd hate to cover that wall up and something happen down the road.
 
Don't use smoking as a guideline to begin soldering. It can be ready way sooner than that. You also need to move the flame around and not just heat one side of the fitting.

Soldering is not rocket science. Solder not taking usually means contamination (not clean enough), joint not evenly heated or oxidation (lack of flux, overheating).

There's almost always a bit of smoke when soldering. Almost every plumber I have used will set off the smoke alarm if it isn't shut of when they are doing the finishing. You guys know what I am talking about. :)
 
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Heat rises, you don't need to go crazy moving the torch around, just apply the solder to the opposite side of the pipe.
 
As others have mentioned, move the heat around the fitting, but how do you know when the joint is hot enough. Touch the solder to the joint on the side away from the flame. If the solder does not flow, heat a bit more and try again. When the joint is hot enough, the solder will flow. It's pretty certain you are overheating, but a clean joint and ample flux is vital as well.
 
Thanks for the replies. I'm confident the fitting and pipe were clean. I really was ocd about that....plenty of flux too. Its a pretty tight spot with a wall a few inches away and a stud even closer. I'll give it another go today.
 
Finch85 said:
I had to redo this particular fitting 4 times. A couple months back, my soldering went well especially given the fact it was my first time. Not so lucky this time. Here goes.

I was having trouble with a 1/2" x 1/2" female adapter (copper to pex). It doesn't leak now but the joint still looks iffy.. A small section of the fitting directly facing me doesn't appear to take solder. The copper pipe was cleaned and fluxed. The fitting was cleaned and fluxed. When it would leak, I'd have to de-solder to remove. Upon inspecting the 3 fittings that didn't take, I could see a section inside the fitting that didn't take any solder. You can also tell this on the front of the fitting too. The last one I just did looks the same in the front (no solder) but I have no leaks so I guess it took inside.

I don't know what to do. I even bought a new brush to clean inside the fitting better but my other one was pretty much new. Should I redo this fitting even though there are no leaks? I'm thinking yes but sometimes I don't leave well enough alone. Maybe its my technique...I heat the joint until it begins smoking, then I reach around the backside to solder first and then I bring it around to the front.
Click to expand...


Why would you be soldering Copper to Pex ?

It could be the material that your adapter is made of, as too why solder does not stick to it.

I am not a plumper, but though the benefit of using Pex was because no soldering was required ?
 
I am sure that you are using a water based flux, and if so, it is VERY susceptable to overheating, which is indicated by it smoking. Once it is overheated and "burns", IT contaminates the joint as if you had not used any flux, which prevents the solder from flowing completely into, and around, the joint. The only cure is to take the joint apart and reclean, flux, and solder it. I have had a joint which was 25 years old "fell apart" when a can of vegetables was dropped on it, so you cannot go by the lack of a leak to determine the joint's integrity.
 
Soldering/ sweating

Finch85 said:
Thanks for the replies. I'm confident the fitting and pipe were clean. I really was ocd about that....plenty of flux too. Its a pretty tight spot with a wall a few inches away and a stud even closer. I'll give it another go today.
Click to expand...

This has been a popular thread and good advice has been given by all. I have been soldering since being a pre-teen; Now I'm an old fart. :p

About 10 years ago, I had installed some new baseboard heating in a room, and man, did I have trouble getting one stinking joint not to leak! I did not realize that the elbow I sweated on to the baseboard element tubing was slightly out of round and there was an area where capillary attraction did not work because of too big a gap. It was my oversight, for sure, but I had to replace that defective (brand new too) fitting. Was cleaned and fluxed "beautifully".

That never happened before to me, nor has it since, but now I am much more careful to make sure that the joint at least "looks right" before heating it.
:D
 
I can see where a lot of the cheap fittings will not take soldering properly, and the sizing differences could be a problem with getting a perfect fit.

The types of Environmental safe Fluxes today do not work near as good as the old school stuff.

Same with the Environmental safe Solder.

I thought it was normal for a Joint to smoke ? lol
 
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DonL said:
I can see where a lot of the cheap fittings will not take soldering properly, and the sizing differences could be a problem with getting a perfect fit.

The types of Environmental safe Fluxes today do not work near as good as the old school stuff.

Same with the Environmental safe Solder.

I thought it was normal for a Joint to smoke ? lol
Click to expand...
yeah, but a joint that is only a few minutes old it too young to smoke;)
 
I hate the waterbased stuff, but find the tinning flux (flux with powdered solder in it) works pretty well. You still need to add solder, but it tins (coats) the surface as soon as it gets hot enough, helping the added solder to flow as well.
 
I redid the joint today ensuring not to overheat it. The solder "sucked in" as it normally should. It didn't look the same when I was doing it last night.

Yes, water soluble flux. This is a copper to pex transition for my double vanity. Maybe I should have stuck with copper but after the trouble I had last night...I'm afraid to try. :)
 
bluebinky said:
Just curious, how long does it take for flux to go bad? I recently had trouble with some that was about 1 1/2 years old.
Click to expand...

I guess that depends on the type of Flux.

I have used flux that was 20 years old with no trouble.

When it drys out then most likely it is to old.
 
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