I have always use an air/propane turbo torch to melt silver, brass, bronze for my investment castings. The torch works fine for small amounts in the 20–30-gram range. I have melted as high as 70 grams, but the process gets much more difficult.
The open puddle of liquid metal loses heat rapidly. I must follow the melt (in a crucible) from my heating area to the mold flask with the torch constantly “playing” on the melt puddle. It’s a two-hand operation with the torch in my left hand and the crucible (clamped in holding-tongs) in my right hand.
The pour is single handed into the top of the mold flask. A growing issue is my (PN) Peripheral Neuropathy sometimes gives me a bit of hand quiver if I do not consciously try to relax my right arm.
I like to do larger pours with larger projects. A few days ago I cast a 60 gram melt of silver for a small bell. Before that I did a large ~200g melt of brass for a solid brass gnome figure. Both jobs pushed my personal comfort limits for torch melting and pouring.
Casting 1700-2000 degree metal is nothing that one should feel difficult or uncomfortable performing.
I must be completely in control of the casting operation. The transfer process from the melt to the pour stage with heavier and larger volumes has begun to exceed my comfort zone.
I considered the melting furnace since day one. However, the volume of the metal for my jewelry work has typically been small. Nothing that a torch could not handle comfortably. Time and old age alter my comfort zones. Now is the time to stop considering and act. Ha!
RioGrande, my jewelry tool and materials supplier, offers several Italian made models of melting furnaces. However, the 1kg (gold melt) capacity furnace with a purchase cost of over $650 has always been a deterrent. The larger sizes are up to $950. A cost not justified for my needs.
Amazon has a huge selection of similar Chinese made melting furnaces. Some under $300. I choose a 1kg capacity furnace (shown) with a little higher wattage than others. I leave my selection reasons there as I am not making recommendations on brands and models. Reasonable cost was the major decision factor.
A closed chamber electric melting furnace with digital temperature control provides a far improved melt environment. Metal is not overheated and far fewer contaminates are introduced to the melt. The crucible is graphite which adsorbs oxygen.
Pour timing is less critical as the metal remains liquid a bit longer between the melt and the actual pour. I can use two hands (if needed) between the melt furnace and the mold flask pour point.
I believe small single item castings will continue to be more practical using the torch melt system. It is quicker than heating a 1kg (about 500g for silver) capacity electric furnace for a 25-gram casting. A load that small is almost lost within the crucible.
I will understand the process method balance once I have a chance to use my new melt furnace. One thing I know for certain. I will be far more comfortable with larger loads with the furnace. Perhaps small loads will be no problem at all… just longer to melt than the torch.