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I am doing some practice welds using technique I learned in plumbing class. I've noticed that in order to make the pipe hot enough to melt the solder I am discoloring the pipe, instead of that coppery color it becomes bluish.

Am I doing something wrong? I've looked at a couple of copper welds and the joints still have that coppery color.

I am using a propane torch and the little solder and flux that comes with the torch package.

Thanks
 

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Nitpicking here, but they're definitely not welds. The solder simply fills the gap between the fitting and the pipe. Not at all similar to welding. :no:

Copper commonly has slight color changes while being heated...Something to do with the metal content of the particular piece. You can often see the change happen while heating. The big issue is that you don't want to overheat the joint because your flux will boil right out and you won't get solder through the full depth of the joint.

The soldering kits often come with cruddy flux. The dark gray/blackish stuff is awful, especially for a newbie. Get a pint tub of Oatey (or similar) paste flux at the home center. It has a thicker texture and an amber color and it tends to be a bit easier to use.
 

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Remember, you apply the solder to the opposite side of the fitting to where the heat is being applied. The flux will draw the solder into the joint toward the heat source.
 

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Maybe this article will help, I just read a bunch of helpful soldering articles, this one seems relevant: how to{link removed - please stop posting the same links to try to drive people to your site}
 

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I think you have overheated the joint. Another disadvantage of overheating is that the flux will boil away sooner and the mating surfaces start to oxidize before the solder flows in to fill the gap. The solder will not stick to the oxidized areas which might be deep down inside and leaks might appear years from now.

It takes practice to get the temperature just right but the joint will hold a temperature plateau for a moment while the flux is boiling and sizzling if the torch flame is not too strong.

Play the flame back and forth over the entire joint as opposed to pointing it continuously at the same spot.

To prevent deforming the washer from heat, turn a faucet or valve to the open position before soldering it into place. Also it is a good idea to wrap the faucet body with a wet rag before starting to solder.
 

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hey dere, Your soldering is probably ok, especially if you were taught by a pro. I like "C" Flux, and just keep touching your solder to the fitting as you heat, and when it starts flowing, back off a little. Discoloration and a little smoke are ok. Make sure not to pick up the MAPP gas bottle - propane only.... good luck
 
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