could someone explain reduction flame?

[newglasstorcher]

I'm a newbi. Of course. I keep hearing about a reduction flame. I"m worried I've got my flame to big or to small. I have a bobcat hooked up to a concentrator and propane tank. Help.

[Kalera]

"Reduction" just means you have too much propane in the flame and it isn't being completely combusted, leaving your flame oxygen-poor. Most glass with get sooty streaks if worked in a reduction flame, but some will also develop a metallic shine when *briefly* exposed to a very reducing flame. A flame can be varying degrees of reducing or oxygenating; a neutral flame contains enough oxygen for the propane molecules to combust completely (by attaching to two carbon molecules, leaving minimal combustion byproduct) but not enough oxygen for there to be remaining free oxygen molecules in the flame.

A neutral flame is the hottest flame, and the most efficient. Both a reducing and an oxygenating flame are cooler than a neutral flame, making them better for certain types of work.

[newglasstorcher]

Thanks for the information. So let me get this right, I'm hoping for a neutral flame. I had a two hour intro, not much hands on time. I came home, set up shop and have had a lot of flame questions. Is the flame to big, cones to big, to small, why won't that cone stay in cone formation? The beads are coming along nicely, I just wonder if I'm working them to hot? laura

[Kalera]

Yep, neutral flame. Your flame is made up of "candles" at the base, and you want each candle to be about the same length; 1/4" to 1/3" or so, primarily blue with a small whitish-yellow tip. You don't want to see any elongated yellow candles, or a strongly elongated center candle, because that means you have a reduction flame. It's OK for the center candle to be just slightly longer than the outer candles.

If your flame won't stay the same size it it most likely because the valves on your Bobcat aren't broken in yet. I've heard that happens with those. In a few weeks they should be fine. Other than that it could be a regulator issue, so if it does't go away talk to your supplier about replacing your regulator.

[bead crazy]

I used a bobcat at the place were I rent torch time. I had a heck of a time getting the flame right on it until one of the girls there told me on a bobcat to have the cones without any yellow and have it so you can see slight lines in the blue bushy part of the flame kind of like you can see slight cones coming into the blue part of the flame. So you will see the cones then after the cones you will see lines inbetween the cones. I hope that this helps it is really hard to explain but just be sure you are seeing slight lines in the lower part of the flame just above the cones. The cones should be about 1/2 inch Look at the flame without you Didys on you will see it better. As soon as you see it you will know just what I am talking about
Lori

[JDeMoss]

Here is a great way to tell what type of flame you have. It works well with boro, but I'm not sure about softglass because I never use it.

This is what Glass Alchemy suggests.

(This is to set a Neutral Flame but teaches you all three)

Get a stick of 987 Amazon Night (it is a dark color changer). Heat to a warm orange glow and allow to cool. If the stick is a light sky blue or has a metallic sheen, the flame is reducing and needs to be adjusted. Reduce the propane content. If the stick is sky blue, it is very reducing and can only be adjusted by reducing the propane pressure at the regulator, usually by 1/2 the pressure (example-from 14 to 7 pounds). If the rod is metallic, adjustments of the regulator of 1/4 pound increments should result in a neutral flame.

So once you can get the rod to come out black (it went in black) it is a neutral flame. Then practice that until you can easily identify when you are at a neutral flame. At this point it is easy to either add oxy for an oxidizing flame or reduce it for a reducing flame.

Good luck, hope that wasn't confusing.

[basket99]

I'm really a newbie and I'm sure this is a dumb question, but --

Can I make a reduction flame with my Hothead torch? I use MAPP gas.

Thanks
Mary

[kbinkster]

Here is a great way to tell what type of flame you have. It works well with boro, but I'm not sure about softglass because I never use it.

This is what Glass Alchemy suggests.

(This is to set a Neutral Flame but teaches you all three)

Get a stick of 987 Amazon Night (it is a dark color changer). Heat to a warm orange glow and allow to cool. If the stick is a light sky blue or has a metallic sheen, the flame is reducing and needs to be adjusted. Reduce the propane content. If the stick is sky blue, it is very reducing and can only be adjusted by reducing the propane pressure at the regulator, usually by 1/2 the pressure (example-from 14 to 7 pounds). If the rod is metallic, adjustments of the regulator of 1/4 pound increments should result in a neutral flame.

So once you can get the rod to come out black (it went in black) it is a neutral flame. Then practice that until you can easily identify when you are at a neutral flame. At this point it is easy to either add oxy for an oxidizing flame or reduce it for a reducing flame.

Good luck, hope that wasn't confusing.
Instead of messing with the regulator settings (which would be important if you were running a Hebert Arnold torch), adjust the oxygen and gas by using the valves on the torch. The Bobcat should run just fine on 5 psi propane and your oxygen concentrator set at 5 LPM.

A tricky thing about reduction flames... they aren't always obvious. When using tanked oxygen and propane, it's easy to see that a reduction flame will have candles with pronounced yellow tips. However, on a concentrator, you can have poor purity (not enough oxygen concentration) and not have the pronounced yellow tips on the candles (also called "cones"). When running Natural Gas, you can have a reduction flame and not realize it until you reduce your glass. So, using a color reactive stick of glass to test your flame chemistry is a good idea. I just wouldn't mess with the regulator settings to make the adjustments.