# Anhydrous Borax



## witelite (Apr 1, 2011)

Will someone please tell a newbie if Anhydrous Borax and Boric Acid are one and the same? If not, where can Anhydrous Borax be purchased.
Thank you in advance,
witelite


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## Anonymous (Apr 1, 2011)

Borax is short for Sodium Tetraborate,not Boric Acid.We do offer a search feature,at the top of the screen.That will help you in the future.


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## Platdigger (Apr 1, 2011)

Anhydrous borax is simply dryer than the type you can buy at the grocery store.
Boric acid on the other hand is just that, an acid. Wiki states that it can be prepared by reacting borax (Sodium Tetraborate) with a mineral acid such as hydrochloric.


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## Harold_V (Apr 2, 2011)

If you use borax for coating melting dishes, or in heats, anhydrous is the way to go---or borax glass, if you don't mind the cost. Hydrated borax comes in either 5 mol or 10 mol concentration, which is the amount of water contained within. It's light and fluffy and hard to use when torch melting because it blows around very easily. It also fluffs up in melting, before becoming tranquil once fully liquefied. By sharp contrast, anhydrous or borax glass are solid and don't froth up when subjected to heat. 

As has already been mentioned, do not confuse boric acid with borax. 

Harold


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## IdahoMole (Aug 19, 2016)

I was sitting here doing some reading and came upon this old thread which reminded me of a question I had when someone tried to sell me some anhydrous borax. Can I take regular off the shelf grocery store borax and bake it in the oven at a low temperature to drive off any moisture thus making it anhydrous?


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## butcher (Aug 20, 2016)

Yes, as far as I know you can slowly heat Mule team borax at 580 degrees for over 3 hours, (that is what I have used in blade smithing), I would not do it in a house oven.

I have not read this article yet but it should give better details.
http://journals.tubitak.gov.tr/chem/issues/kim-02-26-1/kim-26-1-10-0001-2.pdf
I will spend some time studying the article now myself.


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## rickbb (Aug 22, 2016)

Will a house oven even go to 580F?


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## 4metals (Aug 22, 2016)

Once, years ago I had a drum of the wrong type of borax (10 waters) so I just put it in a crucible and melted it, I continued to add the borax until the crucible was full. It is important to realize the stuff expands like popcorn when it is heated as it gives up its moisture so add slowly. When it was all liquid I poured it on to clean dry steel trays where it hardened into thin easy to crush sheets. Easily milled into powder. 

I do remember it was a gas furnace and I did keep the gas throttled back to keep the temperature down so it is possible it hit the 580 degrees but I know I didn't hold it for hours. I assume getting it molten will cause it to lose enough of its moisture for our purposes.


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## Grelko (Aug 22, 2016)

rickbb said:


> Will a house oven even go to 580F?



Normal house oven is around 500-550 F. If it's a self cleaning model, the "clean" setting can go up to 900-1000 F, except you can't set the cleaning temperature.

Edit - added


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## butcher (Aug 23, 2016)

From studying the article above as far as I understand dehydrating the pentahydrate borax, 4Metals is spot on in his advice.

I think you could safely have the temperature much higher because borax has a high melting point 1369 deg F. I have heard of bladesmiths which would just heat it to glass and crush the glass to use the powders, they really did not worrying that much about temperature, just being more concerned with foaming over, as its boiling point is pretty high.

Mule Team borax (soap) decahydrate (Na2B4O7 . 10H2) foams up real bad when it is first heated while it loses 5 water to becomes borax pentahydrate (Na2B4O7.5H2O) up to a temperature of around 200 degrees Fahrenheit,raising the heat slowly helps to keep from foaming so bad as the first portions of water are driven off. 

As water is removed apparently it becomes more difficult to remove more water from it. during fusion From the article posted above it takes about 30 minutes @ 256 degrees Fahrenheit to convert the pentahydrate (Na2B4O7.5H2O) to trihydrate (Na2B4O7.3H2O) with some loss of % borax, borax is cheap so I do not see a problem for us there.

I believe here most of the foaming problems we are concerned about would be eliminated.

I am not sure but suspect if we weren't careful in storage at this stage it could easily gain back its water content, so this is most likely why they spend more time and trouble industrially to attempt to drive off more water from the salts. and this is where they raise the heat to around %71 degrees Fahrenheit for another length of time the longer the time looks like the higher the percentage of yields of Na2B4O7 with around thirty minutes having about 93% Na2B4O7 and 3 hours having a yield of about 95% Na2B4O7.

My wife would hang me if I ruined her oven cooking borax, if I thought I had to do it in an oven, I would be looking at a second-hand toaster oven, or a crucible and a small homemade gas furnace.


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## kurtak (Aug 24, 2016)

Or you could just buy your anhydrous borax from Action Mining :arrow: http://actionmining.com/

Or from Legend Mining :arrow: http://www.lmine.com/

Kurt


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## IdahoMole (Aug 25, 2016)

I had no idea it was such a process. I was thinking along the lines of toasting oak chips in the oven for the aging of spirits. I think for now I will just use the borax as is. Thanks for posting the document Butcher. I will give it a read when I find some time.


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## 4metals (Aug 25, 2016)

When refiners melt with a relatively full crucible, that is when you really see the effect of the water coming off and the flux layer rising in the crucible. It often overflows if you are not careful. I think the smaller guys realize this more than refiners with bigger crucibles because you only have a limited space in your smaller crucibles and you don't want that space to overflow and make a mess.


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