Copper pipe soldering: Flux burns the moment I apply heat

[James Henry]

You should hit all the way around the joint with the solder. When you get a drip, then it's full. You don't have to have a pretty joint it's not a beauty contest.

 

[JohnCT]

Alright, but when I apply solder to the front of the joint, do I need to apply to the back too? Or does it find its way all around?

It will find its way around if everything is done correctly. Your joint might be a bit "dry". Go to that video I linked and watch from 1:18.

With proper pipe prep (sanding/wire brush/emery cloth - *don't* skip! This cannot be emphasized enough!), quality flux, quality solder, and the right amount of heat, the solder will suddenly liquify and get pulled into the joint, even if the joint is upside down. As long as the fitting/pipe is evenly heated all around, you don't technically need to solder 360 like you would do with brazing.

Try a few more joints before committing to that manifold.

John

 

[Sponsor]

 

[John Gayewski]

You need to touch the full circumference of the pipe with the wire. Fill the cup completely.

 

[FreeLander]

Turn your flame down, it's way to high, then go back and forth over the pipe and fitting with the flame and every few seconds touch the joint with the solder, when it melts to the touch remove the flame and only apply the flame to the pipe when the solder stops melting. after the joint is soldered wait for the solder joint to go from shiny to dull then wipe it down rigorously with a cotton cloth.
Wear cotton gloves when soldering so you don't burn your hands on the hot pipe.

Clean pipe and fitting by sanding or brushing.
Flux on inside of fitting and outside of pipe.
Apply heat to fitting and pipe, touching every so often to see if the fitting is hot enough to take solder.

Let set until cool, then wipe the fitting with a rag.
I like to have a spray bottle handy, and gloves. Hot copper will give you a nasty burn if you touch it too soon.

This shouldn't be that difficult. Being where you are, I'm not familiar with your solder and flux brands, so there may be an issue with your supplies. Perhaps you're doing this correctly and your flux is just burning at a temperature lower than your solder needs to flow. Asking a local plumbing supply where you are may clear up any issue with your material.

Regarding cleaning, do not skimp on this stage. Everything you have read about cleaning pipe is not an exaggeration. Your pipe must be thoroughly abraded with sandpaper, a stiff wire brush, or steel wool so the copper shines like gold - inside and out before applying flux.

Here in the States, most amateurs use a typical propane torch which works fine for 1/2" and 3/4" pipes. For larger pipes, MAPP gas is an option as well, but no matter what heat source you are using, it's very important not to scorch the pipe and flux, or the joints will need to be disassembled and *re-cleaned* with abrasives.

This is a very short video that shows what properly heated pipes and solder flow looks like. You don't need to wipe after you make your joint - that's pretty much for show.

Good luck!

John

Brazing requires a lot more heat than soldering.

I DID IT.

Thanks from the bottom of my heart for all your tips and help. I finally did what I kept watching on YouTube. Beautiful shinny abundant melted solder all around.

I desoldered the joint just to see how far the solder went and lo and behold:

It took me four days to grasp the idea of copper soldering. It was fun. It's kind of satisfying looking at my profile pic and the picture above. Started from the bottom now we here !!!

 

[Reach4]

I suggest a little more heat. You would like the solder to climb the coupling a bit and form a very small fillet.