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Any ideas as to homemade flux?


aarya

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Hi all!

Just thought i`d ask if anyone had any ideas as to what i could use as flux, instead of borax. I read somewhere, in a book, that in the old days, they used very fine river sand when they were forgewelding. But i`ve started thinking that this might be good enough when they were welding wrought iron or mild steel together, but i don`t know if it`s able to cut through the scale and oxidation on todays steel.

 

I hope someone can help me with this, or just tell me to get my head outta the charcoal, and get myself some borax. :lol:

Nothing is as beautiful, as the colour of orange-hot steel!

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Get your head out of the charcoal and get yourself some borax. Hey, you said it!

 

There is a reason that almost all blacksmiths use the stuff. Probably that it's available at Mal-Wart for less than $2, look in the laundry detergent aisle for "20 Mule Team." You can always add additional ingredients if you feel the need to improve on it. Iron fillings, crushed scale, and fluorospar, that I've heard of.

“All work is empty save when there is love, for work is love made visible.” Kahlil Gibran

"It is easier to fight for one's principles than to live up to them." - Alfred Adler

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Borax.

 

Fine sand, glass, powdered mud-dauber nests, rice straw ash, etc. just form a glaze on the metal, they do not remove oxides. It'll work on clean steel and wrought iron, but not rusty old wrought.

 

Why torture yourself?

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Well, seeing as my forge is currently an aluminum bucket, filled with heat-resistant mortar. My fuel is wooden charcoal. My bellows are my lungs and a piece of small and thin-bore aluminum tubing, and my anvil is a stump of railroad track.

I guess i can just admit to being somewhat of a primitivist/masochist.

But i guess i`ll just bite the proverbial bullet, and order me up some borax.

 

Is there anything i need to add to the borax, that will allow me to weld rusty pieces of steel together? Or will borax alone allow me to do this?

 

(And yes, i`m quite aware that it`s close to impossible for me to create welding temperatures without a proper blower of some sort, and i am in the market for one. But hand-powered blowers aren`t easy to find in Norway. Either they are in use, or some collector of antiques have grabbed it up.)

Nothing is as beautiful, as the colour of orange-hot steel!

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Try to see if you can find one of those hand powered air pumps for inflating rafts. They look like an oversized bicycle tire pump and push air on both the up and down stroke. There should also be some plans for building a Japanese box bellows around someplace. I think even a large fireplace bellows would outperform lung power.

 

Doug Lester

HELP...I'm a twenty year old trapped in the body of an old man!!!

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Is there anything i need to add to the borax, that will allow me to weld rusty pieces of steel together? Or will borax alone allow me to do this?

 

 

Step one: clean off the rust. :lol:

 

Seriously, light rust isn't a big problem as it will just turn into scale you can brush off at welding temperature. If you are a true masochist, filing down to bright steel will allow you to use clean sand as flux as long as you apply it below scale-forming temperatures. Heavy, deeply pitted rust can cause problems with any weld, no matter how modern the forge and flux. If you are welding cable, internal rust can ruin the whole thing and no flux will remove it. It may still weld, but it will have dark inclusions.

 

What are you trying to weld?

 

Oh, and welcome aboard! Where in Norway are you?

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Doug: Copy that! I had actually looked at a large pump of sorts, that was described as pumping on both the up and downstroke, and i`ll check again, to see if i can find that one again. And while fireplace bellows might outperform lung power, they need to be constructed properly. (The bellows i had, sucked air through the tip. That`s what you get for buying cheap things. <_<

 

Alan: You mean you clean the rust off steel? I usually licked it off. Maybe that explains why my tounge is sore? :lol:

 

Seriously though, i`ve not been in this game long enough to know everything, and i doubt i ever will. Nor have i ever tried my hand at forge welding, but it`s something that i wanna venture into. One thing, is that most basic nordic blades are laminated, mild steel on the outside, and high-carbon steel on the inside. Gives you the edge-holding ability, without the blade as a whole being too brittle.

Also, i`d like to try some axe-making one day.

 

Will the rust matter if you get the temp high enough? I`ve melted steel in one of my more primitive forges in the past, and i`ve regularly melted ceramic tiles and pottery to a glass-like substance, so i`m just wondering.

The mortar i`ve used in the bucket-forge i`m currently using, is good for temps up to 1300 celsius, or 2300 fahrenheit.

(The reason behind all this insanity, is that i`ve got a really old, rather big 30" or so in diameter, rusty circular sawblade from my grandfather. And it`s really pitted, so i was just wondering if there was a way to weld this together with some other steel, and maybe create some damascus of some sort, if i didn`t have to clean the heck outta it.)

Will the dark inclusions make the bond less secure? As in... Splitting the weld?

 

Thankee for the welcome! Rest assured that i`ll pick everyone's brain in turn! :D

 

As to where i`m from: Google maps.

Nothing is as beautiful, as the colour of orange-hot steel!

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Aha! Specific problems have specific answers. :)

 

To get rid of the rusty pits in your sawblade to make a good weldable surface, you have two options:

 

1. grind it smooth, or

 

2. take advantage of your forge and forge it flat.

 

#2 will of course make it a bit thinner, but such a big sawblade is thick enough to lose a bit without becoming too thin to use the way you want to use it.

 

Wire brush the steel from the sawblade before you forge, then wire brush it again at a yellow-white heat the very first heat, before you forge it, and you will have removed most of the rust. After that, forge it flat and the scale will carry off the rest of the rust. You do not want any pits as they will hold dross from forging even with a lot of flux.

 

Tiny inclusions in your weld line will not necessarily cause the weld to fail, fear not. It's just good form to minimize them as much as you can.

 

Rust is chemically Fe2O3. Heating it without reducing it just makes Fe3O4, or black rust instead of red rust. You have to either remove the rust or convert it to iron via reduction and then add carbon and the other alloying elements if you want to keep the properties of the steel. Removing the rust is easier than adding back the things the steel lost by rusting.

 

The place you live looks pretty! B)

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I've been told British smiths who emigrated to the Colonies didn't use flux at all. I've seen some mild forge welded to mild and WI welded to WI without flux.

 

Let the masochism begin :lol:

Kristopher Skelton, M.A.

"There was never a good knife made from bad steel"

A quiet person will perish ~ Basotho Proverb

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Ed: A blow dryer isn`t a bad idea, however, in my experience they don`t give the "oomph" i need/want. And i`ve had a vaccuum cleaner set to blow, where it blew all the charcoal outta the firepot.

But, in my search for a blower, i`ve bought no less than two! A hand powered, double action pump, and an electric air pump.. Thingy.. I`m not sure about the output of the hand pump, but the electric one seem to be just perfect!

(From viewing a few plans on how to make so-called box-bellows, it seems that the hand pump i bought, operates on the same principle.)

 

Now i just need to find a source of borax.

(Which i think i just found.)

 

Onto a different question. I read somewhere that you could add fluorspar to the borax, if you found that the borax wasn`t "flowing" as it should. This isn`t something i have to worry about, if i just keep to simpler carbon steels like 1095, 5160 and 15n20, right? *scratches head*

 

Alan: It sure is pretty up here. Cold and snowy at times, but it`s home. ^_^

Nothing is as beautiful, as the colour of orange-hot steel!

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Onto a different question. I read somewhere that you could add fluorspar to the borax, if you found that the borax wasn`t "flowing" as it should. This isn`t something i have to worry about, if i just keep to simpler carbon steels like 1095, 5160 and 15n20, right? *scratches head*

 

You can add stuff, but for the steels you mention you shouldn't need to. I've gotten away with plain old borax, and sometimes anhydrous borax, for everything I do with those steels. If you Norskies ;) don't have borax in the laundry soap part of the grocery store, you can check with pottery suppliers. They use the anhydrous type for glazing operations.

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Well, i doubt that norwegian grocery stores are as well-stocked as anything you`ll find anywhere, except when it comes to really weird prices. (Don`t start me on how a liter of milk might cost more than a sixpack of beer. :blink: )

But i`ll definately keep my eyes open in some of the better stocked ones. I`m just kinda praying to the higher powers, to give us Norskies :lol: wal-mart or something similar.

 

I guess i`ll give all this a whirl this coming weekend i think. Been a while since i fired up my bucket now.

Don`t have any borax yet, but as stubborn and masochistic as i am, i might even attempt to weld some small pieces without anything, just to see if it`s possible.

Heck, i melted part of a blade i was making in June or thereabouts, so if nothing else, i might be able to melt the two pieces together. :lol:

Which brings me onto something different again... How much carbon is burnt off when you keep steel in the white-sparkly stage? I know all to well about the grain-growth at these temperatures, as back when i first started my endeavour, i thought you needed to get steel white-hot to quench it. -_- Suffice to say, i had alot of *pings* when i quenched in brine. Or i had them go *ping* after they were cool to the touch.

 

Oh, and my possible source for borax, is a blacksmith. Around 15$ US, for about 2.2lbs of borax.. Sounds fair? :unsure:

Nothing is as beautiful, as the colour of orange-hot steel!

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I use a mixture 50-50 of 20 team mule and boric acid from the hardware store. When I did my smithing course I watched the instructor forge weld with straw ash and a clay slurry but he's been smithing for 20 years......so it can be done but I've never tried it. I had a hard time with just borax but the addition boric acid has helped me. Maybe it's just in my mind but it really seemed to help me.

I just saw a bike pump on a forge in a you tube video and it seemed to work fine.

Good luck,

JJ

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When I did my smithing course I watched the instructor forge weld with straw ash and a clay slurry but he's been smithing for 20 years......so it can be done but I've never tried it. JJ

 

" filing down to bright steel will allow you to use clean sand as flux as long as you apply it below scale-forming temperatures." Alan

 

 

Alan,

My concept of the welding process is just like that of the slag process in iron making, the silica requires some iron oxide to be present or it would not flow, that is why Japanese sword smiths only blasts off some of the oxide. Adding too much sand will also create a viscous slag as there may not be enough oxide around to flux the flux. I am sure too much iron oxide would also create a problem.

A phase diagram depicting the relationship between Feo and SiO2 should help in seeing that.

 

Jan

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Jan, that is pretty much correct as far as I understand the process as well. I often go for the simple answer without explaining the mechanics. In my admittedly few experiments with sand as flux, the sand would not dissolve a heavy scale layer. Some oxidation will almost always occur on the steel as it is heated, and a light coat of sand will dissove that as it forms a glassy barrier to further oxidation. That's also why wrought iron can be welded without flux more easily than some other ferrous metals, the slag acts as natural flux continuing its role from the smelting process. Borax is much easier to deal with due to its more aggressive oxide-adsorbing capabilities and its lower viscosity. I have sometimes wondered what would happen if a tiny bit of borax were added to a smelt, in fact... :huh:

 

Oh, and Aarye: In the USA a liter of milk can still cost the same as a six-pack of the cheapest beer, and a liter of mineral water can cost more than that! :rolleyes: Hydrated borax costs about $5 U.S. for about 1.5 Kg, the anhydrous is about the same as what you were quoted and is less messy to use.

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Borax is much easier to deal with due to its more aggressive oxide-adsorbing capabilities and its lower viscosity. I have sometimes wondered what would happen if a tiny bit of borax were added to a smelt, in fact... :huh:

 

 

Alan,

The goal is to duplicate Japanese blade steel in a manner as close to the historical methods as possible ( no press, no borax, charcoal heat source, rice straw and clay etc.) .So I am going to keep borax out of the process, though I agree it is a lot easier to weld with it. Mean while I keep trying to get just the right tamahagane steel from the smelter (this is turning out to be a slower,costlier project than I signed up for, though I should hit it in the next smelt or two).

 

The idea of an inert fluid protective slag surrounding the iron at the bottom of the furnace sounds appealing and some borax may flux the silica depleted of iron oxide but I will have to passs on that for a while. There are other fluxes in the slag, which behave somewhat like borax (NaO and KO and even CaO from the ash of the charcooal).

 

Jan

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i have a 25 layer (or somewhere around there) mild steel billet in my room that i didnt use any flux on. although i'm using a gas forge, so it's a bit easier. but it IS possible to weld without flux.

 

btw. welcome to the forum! these guys here know EVERYTHING about what they do. just ask and your gauranteed your question will be answered. and if you need further assistance i'm sure they'll be able to point you to some photos.

forgewelding takes time to learn, everything has to be just right. so if i were you i'd start by making several practice pieces out of mild steel before you go cutting into that nice big sawblade.

good luck!

 

M

Andy

D

"Behold, I have created the Blacksmith that bloweth the coals on the fire, and brings forth an instrument for his work" Isaiah 54:16

 

www.MADdwarfWorkshop.com

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  • 3 weeks later...

Only thing I know is when watching a vid recently and they were covering the blade with a slurry watery mix they said earth not clay perhaps someone else can explain thw whys and wherefores

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i've used fine white silica sand from a sand blaster for flux on a mild steel lap weld and it worked just fine..i generally use 20 mule borax though just as it is.. i am told that you can cook the borax pure and gring up the remains and wind up bassically with a form of anhydrous borax. good luck jeff

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Which brings me onto something different again... How much carbon is burnt off when you keep steel in the white-sparkly stage?

 

I think it's safe to say that at that point you have pretty much ruined the steel. Cut off the burnt part and start over.

 

Around 15$ US, for about 2.2lbs of borax.. Sounds fair?

 

Sounds like he's trippling his money. I think you can find it cheaper if you look but, if you want to just get on with it 2.2lbs should last a good long time. If he is selling the anhydrous stuff the price is about right.

 

Fluorospar is usually added to fluxes for use on stainless steels. The fluorospar is powerful enough to remove the chrome-oxide layer on the steel and allow it to be forge welded. For simple steels it is overkill and dangerous because the vapors from the fluorospar are an acid that will burn your lungs along with depositing any dissolved metal they carried. The same could be said of all fluxes but, it is a matter of degree. The only people I know of using fluorospar are forge welding stainless steels and they work under the equivalent of a chemistry lab exhaust hood.

 

Take Care,

~Bruce~

“All work is empty save when there is love, for work is love made visible.” Kahlil Gibran

"It is easier to fight for one's principles than to live up to them." - Alfred Adler

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  • 3 weeks later...

I'd disagree on ruining the steel by getting it sparking, just watch yoshindo's video they're sparkling all the time, yes you burn carbon out and yes you blow ther grain size, but both of these can be taken account for. I also have used flurospa and sal ammoniac and don't think they're necessary on normal run of the mill steels, I use them on steels with high chrome +1% and scrap as I don't know whats in it

Edited by JJH
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