This is going to be shorter than normal, I’m at a show, tapping this
out on an iPad.
Prestolites are fine torches, I’ve had one for nearly 30 years, and
its still my “go to” torch for generic heating and larger scale
soldering. Mine’s a Goss, weirdly enough.
But I don’t use it for casting. It just can’t put out enough heat,
fast enough for larger (300-400 Gm ) melts, especially in bronze.
Yeah, it may eventually get them molten, after 10-20 minutes of
slowly oxidizing the melt to bits, but that’s only something I’d try
if I had no other option. It’d be sort of like trying to tow a boat
with my Civic. Yeah, it’ll do it, but I’d much rather use my truck.
When I was teaching an adult-Ed casting class, and had 10-14 flasks
to get through in an hour, I use an oxy/hydrogen torch. Could get
300 Gm of bronze molten in about 2-3 minutes. At home I use
oxy/acetylene, same sorts of speeds. Faster on silver. I’ve watched
people trying to cast midsized silver flasks with B-tank torches,
and it takes FOREVER. Meanwhile the melt just gets oxidized as hell
from being “not-quite-hot-enough” for so long. (Believe it or not,
both the oxy/hydrogen and oxy/acetylene torches were mixed on the
reducing side, and still got the melt going that fast. ) (My
emphasis on speed isn’t for speed’s sake, it’s to reduce the time
the melt is exposed to oxygen while molten. I mix the torches on the
reducing side specifically to give me a gas cover to use to shield
the melt from atmosphere while hot. B-tank torches can’t do that,
and they compound the problem by taking so long to melt midsized and
larger loads. )
As far as temperature goes, everything I can remember reading over
the years put them at about 2500f, and that certainly accords with
my experience of them: nice soft flame, but not very hot. I double
checked that by way of a quick google search last time, and found a
temp chart that listed them at 2660 degrees. What I missed was the
little “c” at the bottom of the chart. Oops. So they are hotter than
I thought the were, but still not nearly hot enough for anything
beyond smallish melts, at least for me. Absolutely great torch
otherwise though. Never meant to imply otherwise.