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I've seen a few recommendations for baking regular laundry borax to make it anhydrous (or at least olihydrous), with the consensus being an hour or two on a pan in the oven. I have two questions:

1.  Will this produce any fumes that will jeopardize the health and safety of my family and my dogs?

2. Will this damage the pan?

I suspect that the answer to both of these is NO, but would rather be on the safe side. 

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Good Morning,

Correct me if I am wrong, water boils at 212f. Only in a closed container will it vapourize at a higher temperature.

When you put the Flux on your work-piece, it is above 1000f. How could moisture possibly be a factor?

Hello!!!!!!!

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22 minutes ago, swedefiddle said:

When you put the Flux on your work-piece, it is above 1000f. How could moisture possibly be a factor?

Hello!!!!!!!

Because the moisture cooking out of the flux makes it bubble and not adhere as well as the anhydrous. 

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Have you tried a side by side comparison of laundry borax vs. anhydrous? I don't apply flux at or over 1,000f I do it as soon as possible before I close the join if possible. A lot of guys believe in applying flux at orange heat say in the 1,600f+ range.

You betcha any hygroscopic moisture boils almost instantly from laundry borax. This makes it foam hard, the steam can form a barrier and slide the flux right off the piece. Foam can also cause small pieces to shift or even be lifted off the join.

Anhydrous borax on the other hand has nothing to boil off doesn't foam at all it just sticks and flows evenly across the surface.

It's a significant difference.

Frosty The Lucky.

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I would use a dedicated container, and I wouldn't do it in my cooking oven, or in my house, Borax is classed as a hazardous substance, a class 5 poison,  and you should be reviewing a safety data sheet before using any chemical to know what the risks are and how to handle it safely.

Here is a link to an Australian SDS.

http://www.safesalt.com.au/boraxmsds.pdf

Reading through it, heating it and breathing the fumes off it is not a good idea. If you must cook it out, do it in a well ventilated area.

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Last year a friend mentioned this to me. So I gave it a try. I wish I could remember the temperature I baked it at, doubt it was over 300 degrees for a few hours.  Anyway I used an aluminum cake pan. Result was a hard brick of borax. I was able to break it up in smaller chunks then ran it through a junky meat grinder to get it back to a powder. Acted the same afterwards for me.   If you want to try yourself use a junk pan. 

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Here's the MSDS for 20 Mule Team: https://www.omsi.edu/sites/all/FTP/files/kids/Borax-msds.pdf. Of note: "Thermal decomposition products may include toxic oxides of sodium and boron", but there's no indication of the temperature at which that would occur. In other words, I still don't see whether or not this would be an issue at the comparatively low temps needed for cooking off the H2O.

20 Mule team corrected since JHCC cant count today :D

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Here is what I have found about the basic chemistry and pharmacology of borax. I am a chemist with some background in toxicology. I can read and understand this stuff but am not a scientific expert in the chemistry and toxicology of boron. The links are updated from a post that I made around 2000 on theForge mailing list.

Borax (sodium tetraborate decahydrate) - Na2B4O7.10H2O
    decomposes losing 8 H2O at 167 F
    boils losing 10 H2O at 608 F
    sodium tetraborate (anhydrous) melts at 1366 F 

This means that if you want to create anhydrous borax so that it does not bubble when you use it, you only have to get it over 608 F. You do not have to melt this into a glass that needs to be reground for use which many folks report doing. Personally, I find that the partially dehydrated compound that I get decomposing it over 167 F, works well for me. It is lots easier to produce as well.

Borax can poison you but it takes quite a bit; ~5-10 g in children and ~15-20 g in adults. Poisoning is most common in children from ingestion of borax used as a laundry agent. Boron has a half-life of about 24 hours in humans; i.e., half of the compound in your body will be excreted every 24 hours. It has been noted that boron can cause lowered sperm count in lab animals. OSHA recommends < 30 ppm inhaled for an 8 hour exposure for borax. This is the general limit set for "nuisance" dusts that have no known inhaled toxicity. Borax is not readily absorbed through the skin. Because of its low skin absorption, boric acid has been used to powder latex gloves. Boric acid solutions have also been widely used to irrigate wounds since it is bacteriostatic (keeps bacteria from growing). Neither boron nor borax are a known carcinogen or mutagen.

Recent evidence suggests that boron (at very element low levels) is an ess
ential to support human life.

Best Regards,
Doug Wilson

References:
The Pharmacological Basis of Therapeutics, Goodman and Gillman
CRC Handbook of Chemistry and Physics

CDC statement on boron:
http://www.atsdr.cdc.gov/toxfaqs/tfacts26.pdf

borax decahydrate as a pesticide/fungicide:
http://www.fs.fed.us/foresthealth/pesticide/pdfs/022406_borax.pdf

MSDS for 20 Mule Team Borax:
Borax Decahydrate (Technical Grade)

 

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8 minutes ago, IronAlchemy said:

Here is what I have found about the basic chemistry and pharmacology of borax. I am a chemist with some background in toxicology. I can read and understand this stuff but am not a scientific expert in the chemistry and toxicology of boron. The links are updated from a post that I made around 2000 on theForge mailing list.

Borax (sodium tetraborate decahydrate) - Na2B4O7.10H2O
    decomposes losing 8 H2O at 167 F
    boils losing 10 H2O at 608 F
    sodium tetraborate (anhydrous) melts at 1366 F 

This means that if you want to create anhydrous borax so that it does not bubble when you use it, you only have to get it over 608 F. You do not have to melt this into a glass that needs to be reground for use which many folks report doing. Personally, I find that the partially dehydrated compound that I get decomposing it over 167 F, works well for me. It is lots easier to produce as well.

Thank you, Doug! Exactly what I was looking for!

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IIRC last time I read a MSDS for borax the LD 50 for rats would scale up to me eating a pound of it to have a 50:50 chance of dying from it;   so safer than table salt....

no skin irritation, one reason it's used to wash baby clothes,

low toxicity inhaled or in the eyes...

Remember there are MSDS for *everything*.  Read the one for water some time...

READ THE NUMBERS as well as the WARNINGS.

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33 minutes ago, ThomasPowers said:

IIRC last time I read a MSDS for borax the LD 50 for rats would scale up to me eating a pound of it to have a 50:50 chance of dying from it;   so safer than table salt....

no skin irritation, one reason it's used to wash baby clothes,

low toxicity inhaled or in the eyes...

Remember there are MSDS for *everything*.  Read the one for water some time...

READ THE NUMBERS as well as the WARNINGS.

The last time I read the report for my local water I was floored by the amount of garbage in it. Things I could not spell (except for when the paper was in front of me and I was looking at the words) much less try to pronounce littered the report. 

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Shoot to many radionuclides in my water up north and too much arsenic in my water down here---someday I'll have a perfectly preserved glow in the dark body...of course building up a tolerance to arsenic doesn't help much as there are so few "classic poisonings" around these days...

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There was a king reigned in the East:    
There, when kings will sit to feast,
They get their fill before they think    
With poisoned meat and poisoned drink.    
He gathered all that springs to birth    
From the many-venomed earth;    
First a little, thence to more,
He sampled all her killing store;    
And easy, smiling, seasoned sound,    
Sate the king when healths went round.    
They put arsenic in his meat    
And stared aghast to watch him eat;
They poured strychnine in his cup    
And shook to see him drink it up:    
They shook, they stared as white’s their shirt:    
Them it was their poison hurt.    
—I tell the tale that I heard told.
Mithridates, he died old.

-- A.E. Houseman, "A Shropshire Lad"

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Just now, ThomasPowers said:

A Shropshire Lad was one of the books I took to college back in 1975 and I read it many times.

The happy highways where you went and cannot come again?

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Been thinking about what vessel to do the cooking in, and have decided to use a sheet pan and baking parchment. Greater surface area = better drying, and parchment means I won't have to worry about the stuff sticking to the pan. Even if a bit does get through, I'll just run the pan through the dishwasher.

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Use a silicon baking pan to bake it and it's EASY to get free. 230f is the soils lab standard for removing hygroscopic moisture. Molecularly bound H2O won't make it boil/foam.

Teenylittlemetalguy makes a very effective flux using borax, boric acid and charcoal. He mixes and grinds it to dust in a tumbler with a few ball bearings. Mix the boric acid and borax before you cook out the water for a uniform blend.

Don't tell me borax is a base and combining boric acid will just make a salt. It's the melting temps that make the real difference in coating the work with an oxygen barrier. Read the ingredients or pull the MSDS on commercial powdered or granular fluxes and read it yourself. Modern forge welding fluxes aren't as effective as the old versions because some or all of the toxic ingredients were removed.

Frosty The Lucky.

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Well, I don't have a silicone baking pan or a tumbler, but I do have baking parchment and a mortar and pestle. Should be fine. 

Yes, I've been planning to make the Alaskan flux since I read the discussion of it a few months ago. Looks good. 

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Dedicated borax cooker?

Why?

I suggest that you try to obtain a large can of food. A can that has a rolled bottom. Not a soldered flanged bottom closure. Enjoy the contents. Then clean said can. It now can function as a borax cooking device. The can may be discarded after the dewatering procedure, if it is crudded up. In other words we have a disposable borax cooker

Do the job outdoors, because it produces a prodigious amount of objectionable smoke.

Just a random thought that appeared after breakfast.

I eat late.

SLAG.

P.S. Need a lot of surface area large cans can be had at restaurants. Especially Italian dining establishments. They use very large cans of tomatoes and prepared sauces.

Edited by SLAG
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