The tubing is brand new.
Thanks!
Good paste Flux, old school tin/lead solder. Some 400 wet / dry 3M emory cloth.
Why are you trying to solder inside the pipe? Soldering works by capillary action.
This should help: https://youtu.be/TYj4uJjaP8g?si=NeqX0fK9sTHI4vIW
Try using a brazing rod with the material.
Nothing that I know of, although it certainly has an oxidation layer that has to be cleared (obviously).
One thing I learned the hard way, having worked in ‘the business’ a while ago, is to be absolutely sure that the flux you use is fresh, as in recently purchased at a high-volume outlet, as using old flux is not any different than using no flux at all.
Copper is quite easy to sweat. The surfaces must be clean, steel wool works great, so does fine emery cloth. A good flux and plenty of heat, preferably MAP gas.
Heat the joint uniformly. When hot touch the solder to it, when it begins to flow it should suck right into the joint, all the way around. Push the solder into the joint as it flows and stop after the first drip on the bottom.
A good plumber does not wait for the first drip to stop, but can tell when the joint is full by the silver ring that develops all the way around.
Trust me.
To get solder to take easily & quickly, use a cylindrical stainless wire brush inside the tube.
Are you building a still?
Must use good Flux!! Sand with good emery cloth.
C-Flux
Use the old lead containing solder; the new lead free stuff isn’t as fluid and doesn’t it wet the surfaces as well. Also make sure your torch has a large enough flame. I use a prestolite air/acetylene when doing copper typing. Also no matter how clean it looks don’t skip the sanding and steel wool step and don’t skimp on the flux.
Or alternatively if you have oxy-acetylene you can braze it that way you can just build a fillet around the outside of the joint, but I find brazing a lot harder to get a nice looking result - probably because I only do it rarely.
Never tried to sweat soft copper, only rigid. For soft copper, I used a flaring tool and fittings.
If you don’t clean the surface with a brush or sand cloth and flux, the solder won’t stick.
Cleanliness is next to godliness. I have used old flux, 50/50 solder (which you can’t get) 95/5 solder etc. the only thing that really matters is getting the copper clean. The easiest way to do this is with a round wire brush (sold with plumbing junk) but I have also done it by rolling up a strip of sandpaper. Clean BOTH peices to be soldered. Apply flux. put the fittings together. Apply heat to the fitting not the solder. Don’t try to solder it until the solder flows freely when you touch it to the fitting.
Remove heat when the solder flows into the fitting. Don’t fiddle with it till it cools a little.
Doesn’t matter how new and shiny it looks, if you haven’t cleaned it today, clean it before trying to solder it.
Sandpaper on the outside, circular wire brush on the inside.
There is always some oxidation/corrosion even on brand new pipe. I use a fitting brush mounted in a cordless drill to clean the inside of the fittings, and medium emery cloth to clean the outside of the pipe. Then I wipe everything clean with a new cloth. Apply good flux generously to BOTH items to be joined, assemble them and sweat the joint to where I see solder all around the seam.
I’ve had 3 joints fail in 30+ years, and they failed because I used old flux.
Hope this helps, enjoy your project.
Ummmm - why do you think they sell the metal brush tools to clan the inside and outside of pipes before soldering them?
Cleans and slightly roughs the surfaces to make them accept the solder.