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Forge weld flux


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Quartz sand melts very well in the forge and was a commonly used flux for forge welding of real wrought iron---a material already containing silicates.

With modern steels a flux that is more active at lower temps like borax is generally used instead as to get good liquidity with sand you may be in the burning region for high carbon steels.

I know your feelings as I remember how surprised I was the first time I melted a ceramic flower pot in my forge trying to use it as an enamelling kiln.

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ok yeha i think i may just start signing my posts. ps. try me with the basic answers i may just know or you may be right frosty and Steve
new guy JR.


Thanks JR. It'll be a lot easier, you'll see. ;)

Borax is all you'll need once you learn how to make a forge work and learn some smithing basics.

Frosty
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Hi Guys,

Borax is very hygroscopic. It loves water. The difference between 20 Mule Team and anhydrous borax is the anhydrous has had the water removed. If you leave it open to the atmosphere it will eventually absorb water until will foam up just 20 Mule Team. As far as borax goes, take your pick, one foams the other doesn't. The anhydrous is a little easier to deal with but it costs more too...


M


Anhydrous is prefered because it does not cool the metal as much when it is applied. Using 20 mule team is some times like spraying water on the iron.

Moral of the story buy anhydrous form one of the blacksmith suppliers, or a pottery supply company. (Anhydrous Borax is used in pottery Glazes)

5 pounds of anhydrous is like 9.5 lbs of borax powder.

Another way of saying this is that 20 mule team is 48% water.(by weight)

Twenty mule team dried out in the oven at 300 degrees for a hours, if done perfectly gets out half the water so now it is 31% (by weight) Doesn't cool the steel as much.

My choice? I have a plastic container with commercial welding compound that I've only used when I'm making the "must not fail" welds.
Other wise I use an old Iron frying pan that my mother broke the handle off of 40 years ago to partially dry the 20 mule team.

I keep the supply double sealed in a plastic container inside 2 gallon zip seal freezer bag. My working supply is kept in a plastic containers that stay closed except when in use.
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Anhydrous is prefered because it does not cool the metal as much when it is applied. Using 20 mule team is some times like spraying water on the iron.


Not to be argumentative, but if you have enough heat to melt the borax what difference does it make? You still have to go back in the fire for a welding heat.

As I said before, use which ever you like. Once melted on the metal they are both anhydrous.

Regards,

M
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Not to be argumentative, but if you have enough heat to melt the borax what difference does it make? You still have to go back in the fire for a welding heat.

As I said before, use which ever you like. Once melted on the metal they are both anhydrous.

Regards,

M


I don't take it that way. I don't worry about what I use except for the really critical welds with pieces that are near finished and don't need any more time the fire than necessary.
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  • 2 weeks later...

Builders sand will work fine, but not fatty sand as used for brickworking mortar as that has a fair % of clay in it. Beach sand can be used as flux but it needs to be sand not 75% crushed shells as is most of the sand around on sydney's beaches, I don't know what the beach sand is on your side of the creek. Sand was all we ever used for fire welding when I started my apprenticeship back in 82, we used to do a lot of fire welding repairing lifting chains, links etc. All that we used at Tech was sand as well, we used that for welding spring steel to mattock faces and picks etc, even had some success usimg it for welding stainless steel to mild (just as a tech exercise).
If you can't get borax sand will be fine. Yes sand will easily melt in a forge fire ("trust me I'm a blacksmith")
Phil

Edited by forgemaster
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