20 Mule Team Borax

[Lobby]

I suspect many of you already know this, but some might not.

I sent an inquiry to the folks at Dial Corp about 20 Mule Team Borax. I wanted to find out whether it was pure, or whether it had some additives to enhance its properties as a soap. Here's their reply:

Dear Mr. Lobby:

Thank you for taking the time to contact us regarding Twenty Mule Team Borax.

Borax (99.5%) and Trace Minerals (0.5%)

Borax consists of the elements: Sodium, Oxygen, Boron & Water
Boron = 11.56%
Sodium = 12.06%

Thank you again for contacting us.

Consumer Affairs


So: Twenty Mule Team borax, that we can buy at the grocery store is essentially pure sodium tetraborate. Exactly what we need as a flux when we melt gold.

 

[Harold_V]

Thanks for posting some very useful information. There's almost always a question about the contents of products that contain reagents that may be useful in refining. This one is a perfect fit for the person who has no chemical supply house near, or who prefers to buy in small quantities.

Harold

 

[dtectr]

Exactly, harold, thanks for acknowledging its place and effectiveness. It is a bit more challenging than lab grade, due to its higher water content, but it does do a serviceable job for preparing melting dishes. Small scale on a budget refiners like myself learn to make do.
Dtectr

 

[Lobby]

Ah, I didn't know that it's water content made a difference. I note that it is a hydrate (deca ?, I'm going off memory).

Does that mean we have to melt it in the dish a bit more carefully?

 

[jack_burton]

I use 20 Mule and about the only difference I noticed in the switch- YES, you have to be careful not to get to close to your melting dish when the borax is first heating up. If you heat too fast, it can pop and some will jump in a random direction, possibly on you. I've had this happen twice. Thankfully, I wear nomex gloves from my volunteer firefighting days.

 

[dtectr]

Do you remember the "snakes" novelty they sold at firework stands? You would light one end and it would wiggle and squirm as it burned? That's kind me how 20 mule team reacts as it melts/fuses.
I think I read on here before that lab grade has been fused then ground, making it more stable and workable. I always wind up with a thicker coating than I would prefer on both my dish and button but it otherwise works fine.

On my next dish I plan to try heating my entire dish then placing it face down on a pile of borax to see if I can get it more uniform.

 

[Geo]

it only takes a couple of good size pinches to coat a dish. you heat the dish and then sprinkle the borax around the top edge of the dish, not in the middle. then push the borax with the flame of the torch. you only want the inner surface of the dish to look wet. remember, heat the dish first and then apply borax by the pinch at a time around the top edge. if the borax puddles up in the bottom of the dish you may have added too much.

 

[jack_burton]

I had that problem at first too, lumpy uneven borax over my dish when I was trying to shake it in off a an old MRE spoon. Now I take a fine mesh china cap and sprinkle the borax on much like you would add powdered sugar to a pastry. No, picture is not me. :shock:

 

[dtectr]

With lab grade that is true. You can do it just like lazersteves video shows and you describe. With the 5- or 10-waters form found in the laundry aisle it gets a little more interesting.
I will try the "edge-sprinkle" technique next time, though. It may give me more control of the results.

 

[publius]

If you drive off the "water of crystallization" prior to use as a flux, it will not spit and jump when heated.

 

[Lobby]

If you drive off the "water of crystallization" prior to use as a flux, it will not spit and jump when heated.

Can you do this in an oven? Hot plate?

What temperature must you reach?

 

[Geraldo]

If you drive off the "water of crystallization" prior to use as a flux, it will not spit and jump when heated.

Can you do this in an oven? Hot plate?

What temperature must you reach?

If you assume that 20 mule team is the decahydrate form, you can dehydrate it completely by heating to around 140-150 Celsius for perhaps an hour. I don't know how hot your hot plate gets, but most ovens will do this (150 celsius = approx 300 F).

An old pamphlet I have on "practical chemistry" suggests that it should be 500 F for 3 hours, but I don't see the chemical need for this, as the hydration bonds with tetraborate should start decomposing at between 75-120 Celsius.

Best Regards, Gerald

 

[lazersteve]

I have both the anhydrous borax crystals and the 20 Mule team borax in my shop.

For glazing dishes I prefer the 20 Mule team as I can grab a chunk and rub my thumb across it's surface which releases a fine dust of the borax. When this is done over a dish that is red hot the borax powder sticks to the surface of the dish almost instantly.

Once the surface of the dish has a thin layer of partially melted borax across 75% or so of the surface I put the torch close to the dish and fully melt the borax. This changes it from a gray color to clear as it rides up the walls of the hot dish.

Lastly, I treat the top lip of the dish the same way.

The whole process takes a couple of minutes and your dish is glazed and ready for action.

I use the glass like anhydrous borax crystals for furnace work when fluxing.

Steve

 

[Harold_V]

Ah, I didn't know that it's water content made a difference. I note that it is a hydrate (deca ?, I'm going off memory).

Does that mean we have to melt it in the dish a bit more carefully?

It is fluffy and very light weight, and will puff up considerably (as it loses water) when being heated. It is VERY easy to blow about with the torch, unlike other choices (more to follow). Once it has been melted, it is no different from either anhydrous or borax glass, both of which are better choices (neither of them display the light weight or puffiness) but are not as easily obtained, and are far more expensive. However, in defense of the higher cost, all of it is borax, none is water.

Harold

 

[Harold_V]

it only takes a couple of good size pinches to coat a dish. you heat the dish and then sprinkle the borax around the top edge of the dish, not in the middle. then push the borax with the flame of the torch. you only want the inner surface of the dish to look wet. remember, heat the dish first and then apply borax by the pinch at a time around the top edge. if the borax puddles up in the bottom of the dish you may have added too much.

Listen to this guy, folks.

Harold

 

[Lobby]

it only takes a couple of good size pinches to coat a dish. you heat the dish and then sprinkle the borax around the top edge of the dish, not in the middle. then push the borax with the flame of the torch. you only want the inner surface of the dish to look wet. remember, heat the dish first and then apply borax by the pinch at a time around the top edge. if the borax puddles up in the bottom of the dish you may have added too much.

Listen to this guy, folks.

Harold

Yeah. His and LazerSteve's posts were quite informative.