I still use a borax cone and slate for most soldering operations -
but I’m rapidly turning to an industrial liquid fluxe as it tends not
to dispace the solder pallions as it heats up.
The slate is used to hold a small amount of water and a cone, made of
crystallised borax, is ground over it until there is a fine
suspension of the borax in the water. This is then applied to the
joint before placing the solder pallions and heating.
It works very well and can outperform liquid fluxes when you have to
heat up a piece for a long time. I prefer it when I am soldering large
Gold and Stone