03-05-2021, 11:08 AM
The GPO solder looks like the stuff used on "wiped" lead joints. The other stuff looks like Tinmans solder so should be OK. Difficult to get an idea of the actual size of those irons, but the bigger one would be the best bet. The Laco flux is OK on steel, but in my experience the work needs to be immaculately clean before you tin steel with the iron, if the solder doesn't take first time, clean the steel again before having another go.
I usually use this flux for soft soldering steel:https://soldersandfluxes.co.uk/p1324/S26...-Flux.html
Which seems to work very well even though the blurb says it's for Stainless (for which it is truly excellent) the fumes are hideous, so if you do use it, make sure there's good ventilation where you're working.
I usually use this flux for soft soldering steel:https://soldersandfluxes.co.uk/p1324/S26...-Flux.html
Which seems to work very well even though the blurb says it's for Stainless (for which it is truly excellent) the fumes are hideous, so if you do use it, make sure there's good ventilation where you're working.