One of my jewelry school friends heard about a soldering method
using water. Does it exist? If so, how does it work? What do we
need to use this soldering technique? Compared to gas, is it more
eco-friendly (I currently use acetylene)? Safer (I would guess so
since the risk of seeing water explode is low...)? Please help me!
The soldering method is the same as with any torch. The method
you’ve heard of is also a torch, burning hydrogen and oxygen. This
forms a very hot, very clean flame, which is often modified by the
torch by bubbling the gas mixture through a flux, or solvent of some
sort, which lowers the flame temperature as needed to something more
manageable. The part about it being water that’s used is correct.
And electric current (from your wall plug) is passed through the
water, which has a strong electrolyte dissolved in it (potassium
hydroxide, usually). The result is that at the two electrodes
introducing the current to the tank of water, bubbles form as the
current breaks down the water into it’s components, hydrogen and
oxygen. The torch then mixes them back together for use as a fuel.
“water” torches are indeed safer than conventional torches, since
there are no pressurized gas tanks at all. The torch produces the
fuel gases from water as needed, so there’s no significant volume of
gasses being stored, nor are they at high pressure. The negative
aspect is that the torch uses quite a bit of electricity. This may
still be cheaper than oxygen and acetylene tanks, but it means the
torch is not free to operate. Also, these are expensive torches.
The cheapest i’ve seen start around 600 dollars or so, if I recall
correctly. The most capable ones are several thousand dollars.