Flux
- Thread starter Samueltb
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Flux is a chemical that dissolves oxide [scale] and acts as a coating to prevent more oxidation .Most forging flux is based on borax .Brazing flux usually also contains borax , soldering flux contains other compounds .Without flux you will never be able to forge ,braze of solder since you have to have clean metal surfaces, not oxide, to join.
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Flux is used to protect and clean the surfaace of the steel when welding. It keeps to O2 away and allows for a clean weld. There are many different flux's aavailable, from 20 mule team borax to expensive blacksmithing flux. I use anhydrous borax and it works fine.
Chuck
Chuck
This brings to mind a question I was planning to post tonight anyways. Not to hijack this thread, but I think it's somewhat relevant.
For the type of forge welding that we do as knifemakers (mostly faggot welding of damascus billets), how much flux do you folks use? I have my own method that's working well for me, but I've heard many things over the years.
Is it:
- Just enough to cover the surface?
- Give it a good coating?
- Too much is never enough?
Just curious what the rest of you folks are doing.
-d
For the type of forge welding that we do as knifemakers (mostly faggot welding of damascus billets), how much flux do you folks use? I have my own method that's working well for me, but I've heard many things over the years.
Is it:
- Just enough to cover the surface?
- Give it a good coating?
- Too much is never enough?
Just curious what the rest of you folks are doing.
-d
From what I've seen and read, "Too much is never enough" would be the answer I would give you. Ive only ever seen people dump flux on. It really seems to make a mess though from when Ive tried it.
Warrior, I think that may be a myth. I use a borax based powdered soap to clean my hands at work- I don't think soap is powerful enough to eat through steel. Other fluxes, maybe. But I don't think a borax based flux would eat through your forge.
Warrior, I think that may be a myth. I use a borax based powdered soap to clean my hands at work- I don't think soap is powerful enough to eat through steel. Other fluxes, maybe. But I don't think a borax based flux would eat through your forge.
From what I understand borax becomes corrosive at high temperatures. That said, it's more known for eating refractory coatings and kaowool than eating steel.
-d
One more thing. Some coatings are more resilient to flux than others. My forge is lined with kaowool, that's coated with Satanite, and the bottom 1/3 or so of the forge is coated in bubble alumina. I've been primarily forge welding and see no signs of evil in the bottom of my forge so far. Darrin Ellis has all of this stuff for sale BTW at his website.
-d
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You really don't want to use too much flux. Yes, it will make a mess and eat your forge, but more importantly, it can interfere with the weld. This is what happens:
You heat the assembly to be welded until it's just barely glowing. Spoon on a little flux over the entire area that will be glowing bright when you get to welding temp--even if you're not going to be welding that spot on that heat. For the purpose of that first weld, I don't think it matters if you use too much, but it doesn't do any good, so why bother?
It has been my experience that flux-related problems show up on the subsequent operations if you're sloppy with your flux. It's when the flux residue is allowed to remain to contaminate your joint for the next operation. If you just add a little more flux over the old stuff, there could be trouble.
If I'm doing a potentially touchy operation like the edge of a Viking-style sword, I try to work in relatively little bites (3-4 inches at a time). Before moving on to another 'bite', I'll run it back up around welding temp and wire brush off the flux residue while it's hot (it comes off easy that way). Then as it's cooling, but still glowing, flux lightly for the next 'bite'.
Flux can be a temperamental friend. Keep things clean. When welding, you don't want flux residue that has been heated and cooled a bunch of times in your joint. Wire brush off the old black stuff and apply a light coat of fresh stuff.
I use anhydrous borax for this sort of welding. I'll use 20-mule-team laundry borax for some others. Don't use welding fluxes with bits of metal in them for a damascus billet.
You heat the assembly to be welded until it's just barely glowing. Spoon on a little flux over the entire area that will be glowing bright when you get to welding temp--even if you're not going to be welding that spot on that heat. For the purpose of that first weld, I don't think it matters if you use too much, but it doesn't do any good, so why bother?
It has been my experience that flux-related problems show up on the subsequent operations if you're sloppy with your flux. It's when the flux residue is allowed to remain to contaminate your joint for the next operation. If you just add a little more flux over the old stuff, there could be trouble.
If I'm doing a potentially touchy operation like the edge of a Viking-style sword, I try to work in relatively little bites (3-4 inches at a time). Before moving on to another 'bite', I'll run it back up around welding temp and wire brush off the flux residue while it's hot (it comes off easy that way). Then as it's cooling, but still glowing, flux lightly for the next 'bite'.
Flux can be a temperamental friend. Keep things clean. When welding, you don't want flux residue that has been heated and cooled a bunch of times in your joint. Wire brush off the old black stuff and apply a light coat of fresh stuff.
I use anhydrous borax for this sort of welding. I'll use 20-mule-team laundry borax for some others. Don't use welding fluxes with bits of metal in them for a damascus billet.