Propane Flame Type

Jewelry Discussion
1

Hello Orchidians,

I often use a propane torch, the kind you buy the bottle at a
hardware store and screw the nozzle onto the bottle, for fusing.999
silver. Example picture follows (ignore the solder. )

Does anyone know if the flame from these types of torches is
reducing, neutral, or oxidizing? I wouldn’t think oxidizing since
there is no supplied oxygen. but I don’t know for sure. Does anyone
know?

Thanks
Mike DeBurgh, GJG
Henderson, NV

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2

Mike,

All of the torches like that which I have used had an approximately
neutral flame. They suck in air for the oxygen supply, choke off some
of that air (thumb, masking tape, a piece of tin etc) and you can get
a reducing flame. If you increase the size of the air inlets (torch
surgery required) you should be able to get an oxidizing flame. Too
much and the flame blows off the torch.

jeffD
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand

3 
Does anyone know if the flame from these types of torches is
reducing, neutral, or oxidizing? I wouldn't think oxidizing since
there is no supplied oxygen. but I don't know for sure. Does
anyone know?

Oxidizing, there is plenty of oxygen in the air. It has to do with
the ratio of fuel to oxygen mixed in the flame not whether you are
using bottled oxygen.

James Binnion
James Binnion Metal Arts

4 
Oxidizing, there is plenty of oxygen in the air. It has to do with
the ratio of fuel to oxygen mixed in the flame not whether you are
using bottled oxygen.

Forgive my ignorance, but if the atmospheric oxygen means the flame
is always oxidizing, then how is it ever possible to create and use a
reducing flame?

Helen
UK

5 
Forgive my ignorance, but if the atmospheric oxygen means the flame
is always oxidizing, then how is it ever possible to create and use
a reducing flame?

I did not say that, I said

It has to do with the ratio of fuel to oxygen mixed in the flame
not whether you are using bottled oxygen.

The original poster wondered about how it could be oxidizing without
bottled oxygen. In the case of that torch the fuel air ratio is
controlled by the fuel orifice and the venturi ports. At best it
might be a neutral flame but they try for the highest temperature
output so that will be slightly oxidizing. But with the proper
orifice and venturi you can make it reducing, neutral or oxidizing
with atmospheric oxygen.

Jim

6

By adding more gas than air to the mix. Burns up the oxygen in the
flame, leaving it reducing.

RC