Fluxing

[Gliden07]

This is one of those I was bored and started to over think a subject questions! If you flux with Sawdust (Which I have and have had good results) the whole point is to convert the sawdust to carbon right? Why can't you just flux with a charcoal or something that has already been carbonized (is that a word??)?? Just a speculative question??

[472x1B/A]

I would answer yes to question number 1. And answer, saw dust is free for me, to question number 2. This probably wasn't much help to you but it's the best I could think of right now.

[220swiftfn]

If you use charcoal instead of sawdust (or pine bedding) you are losing the benefits of the resin......


Dan

[runfiverun]

carbon is carbon.
look up carbourization.
it is different than fluxing, or returning oxides back into the alloy which requires an oxygen free barrier.

[btroj]

The differences that when sawdust burns it produces carbon monoxide. Carbon monoxide prevents oxygen from reaching the surface of the melt and that prevents ore oxide formation.
This combustion also produces reduction of oxides already on the surface, this gets good stuff back into the melt.
Charcoal doesn't do this stuff. The charcoal is the end result, the process is the key.

[7Acres]

Very informative! I use sawdust but didn't realize the process aspect it provides. Sounds like sawdust is even more effective than beeswax, true?

[Gliden07]

This is the information I wanted to know!! I knew if I asked you guys would set me straight!! Thanks, I will continue to flux with the sawdust!

[geargnasher]

Sawdust does two things:

First, the carbohydrates it contains pull contaminating metals out of the mix so they can be skimmed away with the ash. This is called FLUXING.

Second, the PROCESS of the combustion of a hydrocarbon in the presence of metal oxides causes the oxides to be reduced to their elemental state again because the electrons are transferred to form other compounds. Combustion is a reduction/oxidation, or REDOX reaction, where one component trades electrons to become oxidized and the other becomes reduced. In the case of boolit metal, oxidized lead, tin, and antimony become elemental lead, tin, and antimony, while the hydrocarbon becomes carbon monoxide, carbon dioxide, ash, and water vapor.

Carbon monoxide (CO)is probably the best reducant there is because it's "hungry" for electrons, and a lot of it is formed when wax or sawdust is smoldering in an air-starved state right on the surface of the molten alloy/oxide scum. Being starved of gaseous oxygen forces it to gain oxygen from the oxidized metals. Once carbon monoxide grabs what it needs from the oxidized metals, they drop into solution as elements again and the carbon monoxide leaves the scene in a new set of clothes called carbon DIoxide (CO2).

Just adding inert carbon does nothing because the reaction has already taken place outside of the presence of the alloy.

Gear

[runfiverun]

dang it Ian I had to look up carbourization. :lol:

[geargnasher]

I won first place my junior year of high school at the Texas Academy of Science project competition with an experiment involving flashlight batteries. My chemistry teacher was up with me half the night before final presentation helping me prepare for a speech on reduction/oxidation reactions. The nauseating terror of presenting my project and explaining things way over my head in front of about 1300 people (including a three-dozen judge panel of public school teachers and college professors) kinda welded a few facts in my mind. In fact, that's about all I remember of high school chemistry other than the stench of "the sulfur experiment" that each junior class had to perform, and the guy who blew up the fume hood when he put WAY too much carbide in the water!

Gear