[TheForge] Drying Borax (was: Welding flux?)

Mon Jul 22 16:55:28 EDT 2013

That needle scaler ought to beat the battered blender.

On Jul 22, 2013, at 12:40 PM, Jerry Frost wrote:

Okay, I think I see what's happening in the oven  now. Borax being water soluable and hydrophilic changes from a water holding solid to a dissolved state at heat and sets up like cement when it dries or cools. Yeah, that's intuitive speculation but it fits what I've observed. The trick would be driving off the water at a gradual enough rate it doesn't form steam to dissolve the borax. Basically I THINK the borax is turning into hot mud when it foams rather than melting and sets like concrete when it cools or dries. The cooled foam isn't easy to grind at all. the best method I've seen used is to sprinkle a thin layer on aluminum foil, heat and when it cools just roll the foil up and crush as you wish. If you make the layer too thick it just tears the foil to shreds when you try to break it up.

What I thought was a typo was miscommunication, I thought you were talking about driving off hygroscopic moisture. I just didn't read carefully enough, mia culpa.

Funny thing, we had a yard sale toaster oven that used to live in the kitchen I picked up for the shop. Good grief Bruce, if it turns out you and I think alike I'm blaming the TREE. <grin> I LOVE yard/garage/whatever sales I've made some wonderful scores, one of our best was a high quality, say $500 +/- spinning wheel for Deb for $50 and the gal MADE us take about 10 trash bags of processed wool. One of my best recent finds was a needle scaler for $2.00

Jer

On 7/22/2013 10:08 AM, Bruce . wrote:
> Well, I'm not set up to do it right now.  Only heating device I have
> in my shop is a gas forge.  I bought a $2 toaster oven for the shop,
> but it cleaned up so nice (!) that it's now in my kitchen.  Maybe I'll
> look for another.
> 
> I stand corrected on the MP of borax decahydrate -- but that wasn't a
> typo, it was a misreading of a table.  Anhydrous borax melts at about
> 1365 F - no mistake.  But the decahydrate "melts" at 144 F -- WAY
> lower.
> 
> This changes nothing except the recommended drying temperature, which
> should be less than the melting temperature.
> 
> I would be tempted to determine the minimum temperature at which the
> borax would foam, then stop it while it's still foamy and friable --
> easy to grind up.
> 
> On Mon, Jul 22, 2013 at 11:58 AM, Jerry Frost <akfrosty at mtaonline.net> wrote:
>> Give it a try Bruce and you won't tell us again. I'd love to give you a bit
>> about the 1100f typo but you have Andy for that. <grin>
>> 
>> I worked in a soils lab for a while where drying samples is a science. Not
>> the same science but it has to be done right. Hygrocopic moisture can be
>> driven off at 230f. however at around 200f borax is fused into a block, it
>> isn't the glassy slag of melted borax but it's mortar and pestel and elbow
>> grease time. Drying in a gas oven means a minimum 230f and it turns into a
>> white rock at 230f. I've tried an electric toaster oven for a prolonged
>> time, 200f wasn't enough, 212f is pretty much the minimum to drive off
>> moisture and 2 hours did it but meant hard grinding. I only tried a mortar
>> and pestel for a really short time before getting the yard sale blender and
>> even then it was time consuming, loud and beat hell out of that poor old
>> blender. Were I to do it again I'd use the yard sale rock tumbler and steel
>> bearings.
>> 
>> After a couple experiments trying to dry and grind borax I started just
>> melting it in the forge and using it molten. It's so much easier.
>> 
>> Thinking about the plastic bottle I could just put a couple inches of 1/4"
>> copper tubing on the end and not worry about melting it.
>> 
>> Jer
>> 
>> 
>> 
>> On 7/22/2013 5:06 AM, Bruce . wrote:
>>> I've told you guys this already, now LISTEN UP!
>>> 
>>> Chemists dry chemicals at relatively low temperature.  I can't give
>>> you an exact minimum temperature for drying borax, but I would bet
>>> money it's WELL under the melting temperature of the stuff (something
>>> like 1100 F!).
>>> 
>>> Put the borax in a thin layer in an appropriate container into an oven
>>> and bake it for maybe an hour at something under 1100 F.  8^)   I
>>> would start with 250 F, but possibly a higher temperature would be
>>> needed.  A chemist would dry to constant weight, but a blacksmith need
>>> only dry till the stuff doesn't foam when placed on red-hot steel.
>>> 
>>> Store the dry borax in a tight-fitting jar or can, as it will
>>> certainly pick up moisture from the air if you don't.
>>> 
>>> No, I haven't tried to dry borax, as I've never see the need.  I just
>>> get the steel hot enough to melt the borax.
>>> 
>>> The advantage of drying this way is that it avoids the grinding operation.
>>> 
>>> BTW, I've got a friend who puts borax into old plastic grated-cheese
>>> containers for dispensing.  Same problem with those as with squeeze
>>> bottles.  But maybe somebody could fabricate a simple metal squeeze
>>> container -- think of the old oil cans with the bottoms that "oil can"
>>> (that's a verb, boy, that's a verb).  Or maybe get a very large old
>>> oil can, clean out the oil residue, and shorten and widen the spout to
>>> maybe 1" long and 1/4" in dia.  Alternatively, get a one-quart metal
>>> solvent can and drill a hole in the cap.  Fill it maybe half full of
>>> flux powder and use it as a dispenser -- the broad sides will "oil
>>> can" to help dispense the borax.
>> 
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