Will borax damage my propane forge?

B

Benjamin G

Joined
Jul 18, 2018
Messages
13
Hi,
I am making a hatchet right now and need to make a forge weld. I have considered using borax as a flux, but I am concerned that it will damage my propane forge. What are your opinions on this? Are there other fluxes I should consider for this or maybe another way to forge weld the hatchet? (I am relatively new to blacksmithing and have only done a few forge welds). Thank you for your help.
 
Borax will erode soft insulations like Kaowool or softbrick real fast.
Hardbrick is still damaged but holds up much better.
All our gassers get a hardbrick floor. What normally last a few years with occasional flux spatter. But mostly its wear & tear and daily thermal cycling what wears out my floor and lining.
 
Remember, flux isn't glue and you don't need much. If you use too much, eventually you'll build up enough at the bottom of the forge that you'll get flux on everything you put in the forge whether you want it or not.
 
Lieblad said:
Borax will erode soft insulations like Kaowool or softbrick real fast.
Hardbrick is still damaged but holds up much better.
All our gassers get a hardbrick floor. What normally last a few years with occasional flux spatter. But mostly its wear & tear and daily thermal cycling what wears out my floor and lining.
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How can I tell the difference between softbrick and hardbrick?
 
Borax and anhydrous borax fluxes will definitely damage the linings of your propane forge, how much damage depends on a few variables however. If your forge is composed of kaowool or soft IFB without any additional coating, borax based fluxed will quickly dissolve away your insulation eventually reach they forge itself. Hard IFB and kaowool coatings such as satanite will definitely prolong the life of your forge, but ultimately, the same fate will occur. Remember, flux resistant is not the same as flux proof. I’ve had a kaowool lined forge without any coating that I’ve forged welded Damascus in before, and using 20 Mule Team Borax as flux, I had to replace my lining after 6 or 7 welds. Not terrible, but not great either. One way to prolong this is to use a small cut of hard IFB at the bottom as a table so that flux drips onto the hard IFB and not your softer linings, then as it wears down, replace it. If you are only going to do 1 or 2 welds, I’d say go for it. If you are going to make a habit of forge welding, then you might consider building a dedicated forge welding forge or upgrading your current set up to be more tolerant of the fluxes. Another option is flux less forge welding, but I would only consider that when you have a bit more experience.
 
J.Marc said:
If you are going to make a habit of forge welding, then you might consider building a dedicated forge welding forge
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I wish I had one, but this is after many years of forging.
 
weo said:
He means how is your forge made? What does it look like? What materials is it made of?

Soft brick is softer than hard brick. Go to a material supply company and they'll know the difference.
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Karl B. Andersen said:
What type of forge are you using?
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The forge is a Diamondback ironworks, two burner, propane forge. It is a steel box with a firebrick insulation. The firebrick on the walls and roof the forge is softer than the firebrick on the floor of the forge. I have pictures, but I can't get them to upload.
 
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J.Marc said:
Borax and anhydrous borax fluxes will definitely damage the linings of your propane forge, how much damage depends on a few variables however. If your forge is composed of kaowool or soft IFB without any additional coating, borax based fluxed will quickly dissolve away your insulation eventually reach they forge itself. Hard IFB and kaowool coatings such as satanite will definitely prolong the life of your forge, but ultimately, the same fate will occur. Remember, flux resistant is not the same as flux proof. I’ve had a kaowool lined forge without any coating that I’ve forged welded Damascus in before, and using 20 Mule Team Borax as flux, I had to replace my lining after 6 or 7 welds. Not terrible, but not great either. One way to prolong this is to use a small cut of hard IFB at the bottom as a table so that flux drips onto the hard IFB and not your softer linings, then as it wears down, replace it. If you are only going to do 1 or 2 welds, I’d say go for it. If you are going to make a habit of forge welding, then you might consider building a dedicated forge welding forge or upgrading your current set up to be more tolerant of the fluxes. Another option is flux less forge welding, but I would only consider that when you have a bit more experience.
Click to expand...

Thank you for the information, I will make sure to keep all of this in mind.
 
J.Marc said:
Borax and anhydrous borax fluxes will definitely damage the linings of your propane forge, how much damage depends on a few variables however. If your forge is composed of kaowool or soft IFB without any additional coating, borax based fluxed will quickly dissolve away your insulation eventually reach they forge itself. Hard IFB and kaowool coatings such as satanite will definitely prolong the life of your forge, but ultimately, the same fate will occur. Remember, flux resistant is not the same as flux proof. I’ve had a kaowool lined forge without any coating that I’ve forged welded Damascus in before, and using 20 Mule Team Borax as flux, I had to replace my lining after 6 or 7 welds. Not terrible, but not great either. One way to prolong this is to use a small cut of hard IFB at the bottom as a table so that flux drips onto the hard IFB and not your softer linings, then as it wears down, replace it. If you are only going to do 1 or 2 welds, I’d say go for it. If you are going to make a habit of forge welding, then you might consider building a dedicated forge welding forge or upgrading your current set up to be more tolerant of the fluxes. Another option is flux less forge welding, but I would only consider that when you have a bit more experience.
Click to expand...

What is a dedicated forge welding forge? Is it just a coal forge or is it something different?
 
How can I tell the difference between softbrick and hardbrick?
Click to expand...
Hardbrick is hard (duh!!).
Softbrick is soft, you can almost dig your fingernails into it. Its very lightweight too.
Seriously,
Thats sort of oversimplified, there are several types of refractory brick, but in general hard is hard & soft is soft.
 
A dedicated forge welding forge is designed to just forge weld and not melt from the flux. Usaly it’s a vertice forge with a cast floor and can have a layer of kitty litter. The sides are usaly refractory wool that has a thick coating of hard refractory. The burner enters the forge at the bottom and the openings for your steel are at the top. So it does not have a floor for you to set your steel on. All the borax drips off the billet and collects on the lower floor. Takes awhile to get up to temp but handles the temp and borax ok. Borax when hot will eat wool and refractory brick like water on Cotten candy. Nothing sucks more then when your forging and you got borax on your floor and it gets all over the blade your forging.
 
Being that its a diamondback(kk) forge, my suggestion would be to not bother, and just let it die a fluxed death, sooner the better. the blacksmithing/bladesmithing community is better off without that stain associated with it.

As for protecting a forge, i do what dave lisch does. Kaowool soaked in mizzou slurry, set in place, then coated with a thick layer after. Ive seen this combo take years of fulltime forge welding abuse before needing a new coating.
 
Benjamin G said:
What is a dedicated forge welding forge? Is it just a coal forge or is it something different?
Click to expand...
I think JTKnives answered that for me, but a dedicated forge welding forge is one that is built with chemical resistance in mind over anything else. Kaowool is traded out for castable refractory, hard brick is the preferred brick, clays are used to protect further, ect. The issue is that denser refractorys typically take a while to adequately heat up for forge welding. One trade off, but it has its merits. One suggestion I have is that you should also consider making a forge that can be disassembled enough so that if you have to, you can do repairs and touch ups, this way you get more life out of your forge.
 
JTknives said:
A dedicated forge welding forge is designed to just forge weld and not melt from the flux. Usaly it’s a vertice forge with a cast floor and can have a layer of kitty litter. The sides are usaly refractory wool that has a thick coating of hard refractory. The burner enters the forge at the bottom and the openings for your steel are at the top. So it does not have a floor for you to set your steel on. All the borax drips off the billet and collects on the lower floor. Takes awhile to get up to temp but handles the temp and borax ok. Borax when hot will eat wool and refractory brick like water on Cotten candy. Nothing sucks more then when your forging and you got borax on your floor and it gets all over the blade your forging.
Click to expand...

Thank you for the information.
 
J.Marc said:
I think JTKnives answered that for me, but a dedicated forge welding forge is one that is built with chemical resistance in mind over anything else. Kaowool is traded out for castable refractory, hard brick is the preferred brick, clays are used to protect further, ect. The issue is that denser refractorys typically take a while to adequately heat up for forge welding. One trade off, but it has its merits. One suggestion I have is that you should also consider making a forge that can be disassembled enough so that if you have to, you can do repairs and touch ups, this way you get more life out of your forge.
Click to expand...

Ok, thank you for the information and the idea.
 
Lieblad said:
Hardbrick is hard (duh!!).
Softbrick is soft, you can almost dig your fingernails into it. Its very lightweight too.
Seriously,
Thats sort of oversimplified, there are several types of refractory brick, but in general hard is hard & soft is soft.
Click to expand...

That is what I thought, I just wanted to make sure so I could identify the firebrick that was in my forge. Thank you.
 
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