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borax vs anhydrous borax


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There has been a lot of talk about using borax as a flux, some use it straight from the box and some talk about using anhydrous borax. The difference is the chemically attached water. Borax can be easily converted to anhydrous borax by baking in the oven to drive off the water.

You drive off the water at 250-300 degrees F to turn borax into anhydrous borax. So what is different from using 1500 degrees F to do the same thing. How is using borax on hot steel different from using anhydrous borax as any water will be driven off as soon as it comes in contact with the hot steel anyway.

Edited by mod07
typo
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Foaming is the difference in use. As the water boils off the borax is more fluid and in motion of it's own (boiling) which means more spills and spatters in your forge. Molten borax is caustic and this is what eats silica based refractories. The boiling water only gets more on the liner, it has no chemical effect.

The other problem with the foam is it's tendency to move small parts out of position.

My solution is to simply apply the flux and let it get the foaming over with before I mate the pieces.

My solution to flux erosion is to use a high phosphate or phosphate bonded refractory which is unaffected by caustics at heat.

Frosty

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  • 12 years later...

 Very, very necro’d.

On 10/30/2008 at 9:01 AM, Glenn said:

There has been a lot of talk about using borax as a flux, some use it straight from the box and some talk about using anhydrous borax. The difference is the chemically attached water. Borax can be easily converted to anhydrous borax by baking in the oven to drive off the water.

You drive off the water at 250-300 degrees F to turn borax into anhydrous borax. So what is different from using 1500 degrees F to do the same thing. How is using borax on hot steel different from using anhydrous borax as any water will be driven off as soon as it comes in contact with the hot steel anyway.

You can drive out the water by simply heating it in an oven at a low baking heat?

Could I use a glass baking dish from  a thrift store or yard sale, or is  a metal pan better?

What about a mixture of borax and boric acid?

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I just use plane ole 20 mule team borax and boric acid is a good, but not a critical addition. It can be found as boric acid on the counters of many pharmacies and has no additives. Price is cheap, or it was last time I bought it.

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A lot of roach killers such as Roach Prufe or Roach Away are almost entirely boric acid, usually for a LOT less than the pharmaceutical grade stuff at the drugstore.

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I think the price difference wasn't much, but I don't remember. I think I got it at the pharmacy because i went to the grocery store more often than the hardware store.  I must admit the name and not being able to find out just what that little bit of other stuff was made me a bit nervous. :)

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On 10/30/2008 at 2:19 PM, Finnr said:

Baked in the oven on the other hand takes up moisture fairly easily.

I tried baking in the oven before to drive off moisture and it ended looking the same but being a big solid mass. I broke it up and ground it up but it seemed to work about the same as regular borax would. If I were to try again I would do as Jph has in a video on and others have mentioned,  and really melt it then break it up and grind it up. That way the work should atleast be worth the results. 

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That’s because baking doesn’t remove the water of crystallization; you have to melt it to do that. 

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Anybody who is remembering what I'd said about driving off hygroscopic moisture from borax making it anhydrous. I was WRONG, there is moisture bonded molecularly that requires higher temperature to drive off. The material and links in the "Absolute last word . ." post provided the chemistry involved. 

You have to MELT it. 

Having tried to grind re-solidified borax I just buy welding/ brazing/ silver solder/ etc. flux at the welding supply. A 1lb. can cost just under $26 and works a treat.

Frosty The Lucky.

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On 5/11/2021 at 3:28 PM, Steve Sells said:

have been using Roach Proof as my source of boric acid for years

I rest my case.  :).  ;)

I did the melting thang once and bought the high price spread once as well. I just use plane ole 20 mule team borax with a little boric acid thrown in for bragging rights.  :)

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I have a can of 20 mule team borax and about 1% boric acid I've been using for decades. The Peterson's welding, brazing, etc. flux works about as well as the Black magic a demonstrator was using. Better, the Peterson's cost less than 1/4 as much and was on the shelf at the local welding supply. No shipping, no waiting. 

Tristan's Alaska Flux has a BIT of powdered charcoal mixed in and works better than either. Just do NOT add a lot, about 1/2 TSP to a can does the trick IIRC. Tristan will correct me if I misremember I'm sure. 

Frosty The Lucky.

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I bought a bottle of Iron Mountain flux yesterday. It was very spendy. $30 USD for a small squirt bottle. I only had time for one go last night, but is seemed to work better than my 20 Mule Team/Roach poison mix. It did not bubble and stayed where I put it instead of sliding off. 

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After going through the trouble of melting and grinding up some twenty mule team borax I decided to look online to see why people are going through all the trouble instead of just buying anhydrous borax. There is no good reason. It's about 6 bucks a pound on Amazon so if you're curious to try it you can save yourself a lot of trouble and just buy some. 

Pnut

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You know pnut, a person could make the same argument about just buying a gate latch rather than forging one. I thought I'd check and you can get Peterson #1 Blue flux on Amazon for $19.98 at this moment and you don't have to mix anything. 

I've been using it for years to good effect.

I understand what happened to the old Ez Weld, Cherry Weld, etc. is EPA made them take the really toxic chemical out of it. EPA would make JPH remove it from his steel glue if he were selling it. 

If you have some of the older formula flux hold it dear, it's like magic. I've watched a contest between a couple farriers to see who could weld at the lowest temp. Both made good welds at dull red. Not with the new formula flux though.

Frosty The Lucky.

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One reason to make anhydrous rather than buying it is to use up a box of 40 Mule Team.

Another, of course, is just for the fun of it. 

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What is:

Anhydrous Borax Granular Graphite Crucible Powder Deoxidizing Casting Flux
 

Just anhydrous borax or anhydrous borax with graphite in it?

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Both are excellent reasons!

Here's the real deal,,,.  ;) I don't know if any of you remember Judd Nelson. A legend from the Smokey Mtns (if I remember correctly) featured in the Foxfire books, a hoot to watch at long ago ABANA conferences to mention a few of his highlights.

Well, his way of applying 20 mule team borax was to grab a 3 or 4 finger pinch and toss it at the fire.... Never missed a weld and, of course done in broad daylight. So have fun playing with fluxes and never forget,,, the fancier the name,,, the better the bragging rights.  :)

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