Rosin core for electrical.
For copper pipes, just regular old solder, that you get in the plumbing section of the hardware store. Don’t buy the kits with the “non-greasy” flux, it doesn’t work particularly well. Buy the stuff that looks like a very light colored grease, and you shouldn’t have any problems.
There are different types of solder for copper pipes too. If you go into a plumbing supply house they often give you solder meant to be used with professional style torches (relatively powerful devices). Lower-temperature solder - available at Ace, Lowes, etc. - is easier to work with using regular propane torches.
IMHO, 63/37 (if you can find it) is much easier to control, especially in small / tight places or for the novice. And yes, rosin core only for electrical work.
For copper pipe, I’d recommend acid core 60/40 and a flux paste. Rough up the areas you want to join with emery cloth, apply flux and assemble. Heat one side and apply solder to the other. The solder will flow wherever the flux was applied.
With both types of soldering, do not apply the solder where the heat source is. The idea is not to “melt the solder into the joint”, but get the work hot enough to melt the solder so that it flows into the joint.
60/40 may be difficult to find as lead based solder isn’t permissible for potable water systems. IIRC 95/5 tin/antimony is one replacement-I like the silver bearing solders myself.
And, lest we forget that we don’t wanna lose and Dopers to hobbies- using acid core solder is somewhat dangerous in terms of vapors. Do this hobby outside, or with a strong fan blowing and windows opened up.
Using rosin core with delicate electrical wiring, I typically have a little desk fan going but not a huge rush of air. I’m already a dim bulb, no need to inhale any lead fumes.
I’m actually doing a project with copper pipe that isn’t plumbing related, but I want to be able to solder the pipes together. Plus, it never hurts to have a new skill.
I just have to share this. This is really weird. I have never in my life made anything out of copper plumbing bits and tubing.
Until last week. A week ago, I had bought right angles, “T” joints and about 15 feet of 1/2 inch tubing. Tried soldering it using that crappy flux/solder paste. Wound up drilling a LOT of holes and driving in rivets instead.
Just…weird, that I’m reading this thread and last week was the first time I’d ever tried soldering copper tubing.
Go to the home store, buy a torch kit, a pipe cutter, some copper pipe and a bag of elbows.
Next, draw a line on your garage floor with angles of less than 90 dgrees.
Now sweat together this combination so it follows your line exactly.
If you can do that you are ready to start sweating pipe in the walls.
Bear in mind that your walls may be built of materiels that burn. Any plumber worth half his salt pays attention not to burn down the building he is plumbing.
Arg, that sounded really harsh. Not to mention not realloy answering the OP.
For plumbing applications, use silver bearing solder. Or (non-lead) if labled that way. Like DWC states do not use ANY lead bearing solder on water joins. (potable or non) You will likely violate code.
To answer the OP directly, I like bar stock silver solder in conjunction w/ tinning pase flux myself.
But what the fuck would I know? I was only a rough-in plumber for three years.