Hello Sheridan: Oxy/Propane is the combination I use on almost
everything, ie. sizing, retipping, chain repair, assembly, casting,
lead soldering, all platinum work. A tank of propane lasts forever.
It is cleaner and is recommended for platinum work and casting gold
Oxy/Acetylene is what I use for large silver Items and for soldering
silver or gold rings with heat sensitive stones underwater. I do not
use it for casting because it is not recommended.
I set up my propane and Acetylene tanks with "quick disconnect"
fittings on the regulators and the end of my fuel gas line with the
same. This way when I need to switch gasses all I have to do is
unplug from one and plug into the other. I use a “little torch” and
sizes 3,4 5,6 and 7 tips. As a full time bench jeweler I usually have
to switch over to Acetylene once or more a day.
Michael R. Mathews Sr. Victoria, Texas