Hi has anyone ever had an experience like this? I'm a builder and the plumber I use is always really good never had any problems. However on a current job he has had to re-do a soldered copper joint on a radiator pipe 4 times and it's opened up again. On the first 2 occasions he dried the joint out with wet vac, polished the copper and the solder ran round perfect. On the 4th attempt he used york fittings, again looked like a faultless solder he even put leak additive in the system, it was absolutely fine for 2 weeks so I put the skirts back on but its opened up again. Got to take skirts off again customer is fuming but I can't see how it's the plumbers fault. Bear in mind there are probably 8 other soldered copper joints on the job all fine and I've never known any of his work to leak on over 10/15 jobs. Is there any circumstance in which the solder just won't take?

Hi russ, two things that will cause a leak is moisture and a dirty fitting or pipe, when he's redone the leak, did he use the same spot on the pipe? After four sanding to clean the pipe may be to small.

A real plumber will see this and respond so hang tight. Good luck

Have seen it and experienced it, as well. It looks like "dirty" pipe or residue of water in the pipe creating steam during soldering. In addition, it may be that pipe was not heated up evenly, creating weak seal on opposite side of the flame.
What I would do in this situation is, I would send somebody else over than the original plumber to do the repairs. Milo