How to solder correctly

[southernnaturelover]

I am remodeling a bathroom in my house (not the house mentioned in my other thread). My house has copper piping and I can never seem to get the soldering right. I always make sure the pipes are clean and I apply flux before soldering. But, the solder seems to lump up and sometimes looks burnt, rather than melting over it like butter. Also, the solder that does stay on the pipe can be scraped off with my fingernail. What am I doing wrong here? I'm beginning to hate copper pipes!

[Plumb or Die]

Didn't clean right, didn't flux right or use right flux, torch too hot, not hot enough, wrong solder....... One or more of those. Give us more info on what you're doing.

[jadnashua]

Heat the fitting, not the pipe, move the torch around so you don't apply all the heat from one side, don't put the flame on the solder (in fact, you can usually remove the flame while putting it on). As you are heating the fitting, periodically test to see if it is hot enough by placing the tip of the solder wire on the fitting/pipe junction. As you heat, it will at first, not do anything, then as you approach the right temp, it will stick a little, and then when you place it there, it will melt and flow into the joint. Both the outside of the pipe and the inside of the fitting need to be bright and shiney; don't touch it with your fingers after cleaning (oils are bad for the joint), cover both the fitting interior and the pipe exterior with flux, then go for it.

Note, you'll never get a good solder joint if there is any water at the location of the fitting. It is also a good idea to ensure that there is an exit for any possible steam that may be generated or it will try to escape through the molten metal in the joint, which will often compromise the joint.

[southernnaturelover]

"cover both the fitting interior and the pipe exterior with flux, then go for it."

So you're saying I shouldn't apply any more flux to the outside of the joint before soldering? It almost does seem like it's the flux causing the solder not to stick. I have been applying it to the outside before soldering. It's also possible I'm getting it too hot.
This is my second bathroom remodel. Last time I took the easy way out and used flex hose with gaskets and compression fittings to connect the shower faucet. I wanted to do it correctly this time with all copper like it was originally.

[Gary Swart]

Follow JDNASHUA's description. I don't think you can apply so much flux that the solder will not flow, you might be wasting flux by applying more than needed, but to my knowledge, it doesn't hurt anything. The way you describe the reaction of the solder makes my suspicious of the presence of water. Even a small amount will create steam and prevent the solder from flowing. Getting pipes completely empty can be a challenge at times, but it has to be done.

[frankthetank]

I'm a total newbie, but i've sweated around 50 tees/elbows/couplings/valves/etc and i clean the pipe up good (sand to a nice finish/wipe off), apply my oatley 95, and join the 2 parts completely together. After that i heat up the valve/coupling/etc and not the pipe...flux starts sizzling good after applying MAPP to it for not very long and then i just make rings around the pipe trying to fill in all the gaps. I've read that if you get the drop of solder at the bottem the joint should be full. I must be doing something right, because after a few failures, everything is holding up. Practice practice practice. If water is in that pipe its hard as heck to get even the solder to melt, even with mapp. You've got to get that water out of the pipe.

[CHH]

I am surprised that no one has mentioned the ritual sacrifice of a small furry creature to appease the gods of sweat joints. I'm not sure if it's really required or not but it can't hurt (unless you're the small furry creature).

In addition to the other suggestions, apply the hotest part of the flame to the base of the joint while heating. Watch the flux. You'll see it melt at which point it should spread evenly. At some point before theflux starts to burn off, the joint will be hot enough to melt the solder. Touch the solder to the joint and it should melt instantly. If you expose the solder to the flame too early it is possible to oxidize the solder and then it won't melt correctly. The solder should only "see" heat from the joint, not the flame. If you do see the flux burn off, stop because you'll have to re-prep the joint.

A couple questions: what type of torch are you using and what type of flux.

In general, the hotter the torch the easier it is to sweat.

With flux, I had an old tub of Oatey green that was horrible. Got a fresh tub of Lennox green and the joints were easy again...

[statjunk]

I use mapp gas and I will put the flame right on the fitting. Using the hottest part of the flame. Usually goes quick like that.

If you have water in the pipe use a shop vac to get it out cuping your hand over the pipe and use the smallest vac attachment that you have.

Tom

[southernnaturelover]

I'm using a regular Benzomatic torch and Oatey #5 flux. It could very well be some water in the pipe that I don't see. I'll give the shopvac method a try.

[frenchie]

No flux outside the joint. Part of the function of flux, is it draws the solder into the joint. If it's slobbered all over the place, the solder follows it all over the place. (too much flux will also leave you with nasty-smelling water.)


One trick that I learned from an old pro, that helped me a lot, is to look at the color of your flame, where it's bouncing off the pipe.

On the most basic level: if there's any water present, as it heats up the steam makes the flame go bright yellow. Very obvious & noticeable when you know what to look for.

The more subtle thing is that when the copper's just perfectly heated, there's a very light touch of green in the flame - just a tiny bit, where the flame's bouncing off of the pipe... This one took me forever to learn how to spot, and if you've got a whole lot of green, it's too late: the pipe's too hot, and you're boiling away all the flux. Start over (clean, flux, fit, sweat).*

It's well worth it to practice a bit before you try sweating any real pipe. Get a whole bunch of various fittings, some pipe, and set yourself up outside (flux fumes get nasty, after awhile). Try things out, maybe even put some water in one, just so you know what it looks like... get comfortable with it.

[GrumpyPlumber]

I am surprised that no one has mentioned the ritual sacrifice of a small furry creature to appease the gods of sweat joints. I'm not sure if it's really required or not but it can't hurt (unless you're the small furry creature).
...

YOU HAVE BROKEN THE SACRED VOW OF SILENCE!
You will pay...in the after life.

[rdtompki]

I'm a DIY'er, but I've done a lot of copper plumbing(without leaks except where I forgot to solder). When I had a very large master bath to do I switched to a turbo torch that had a built-in striker. The striker is a big safety feature since you don't have to keep the torch lit. The turbo feature makes 1/2" and 3/4" pipe and fittings a breeze to solder with propane as opposed to the forever wait for the pencil flame in the standard low cost kits. I bought a MAPP bottle, but found I didn't need it for this size pipe.

Rick

[Dunbar Plumbing]

Soldering

Follow the above

[Wet_Boots]

There is one soldering problem that can happen, even if everything is properly prepared, and correct blowtorch technique is used. It happened to me a few years back, about when I switched from using small tins of paste flux to a small jar of flux (Nokorode brand) - solder just wasn't flowing properly. Luckily, I had a bit of flux left in an old tin, used it instead, and everything went fine.

Turns out that the Nokorode flux had 'separated' and I wasn't getting any/enough of the active ingredient when I dipped the brush in the jar. For all I know, my no-name tins of paste flux had also been separating, but they're so much shallower, that I was scraping the bottom of the tin whenever I dipped the brush. So I give the Nokorode jar a stir, whenever I'm doing some soldering, and no worries.

[GrumpyPlumber]

The blowtorch prolly didn't help either.