Problems with boric acid and denatured alcohol

Jewelry Discussion
1

hi all

im having a bit of trouble getting this boric acid to desolve in the
denatured alcohol, the boric acid says “tech grade” and it seems
like fine grains but it just dont seem to desolve, once the item is
dipped and burned off when it is being heated the coating seems to
gather up an leave small uncoated patches, i get by with it so its ok
but this is just a question of is there a better way to get it to
desolve and when i go to use it i give it a good mix but then it
seems to settle more or less straight away, it is a case of mix the
boric and alcohol to get it off the bottom, drop the while swirling
the jar, then trying to fish out the item while the jar is on the
move someone said about warming the alcohol up with the jar in a pan
to get the boric acid to desolve a bit better but that to me dont
seem very safe to me having a open flame close to it, i did read on
some site about boric acid and borax desolved in water as a firecoat
does anyone have any comments on that?

id be greatful of anything info you could give

regards
jason

2 
i did read on some site about boric acid and borax desolved in
water as a firecoat does anyone have any comments on that?

I posted this recipe before. Combine equal parts of boric acid and
borax, fill some small pot to the rim, ( I am using small milk
warmer), add water - as much as it can take, and heat it until
dissolves. You can only use it hot. When cool, it is solid. It works
well, but coat is very heavy. If lighter coat is required - combine
with alcohol.

Leonid Surpin

3

SOME of the boric acid IS dissolved. Just mix up the liquid/powder
and paint on or dip into this mixture. The Boric Acid crystals never
go totally into solution.

John Dach

4 
im having a bit of trouble getting this boric acid to desolve in
the denatured alcohol, the boric acid says "tech grade" and it
seems like fine grains but it just dont seem to desolve, once the
item is dipped and burned off when it is being heated the coating
seems to gather up an leave small uncoated patches,

Boric acid is only slightly soluable in denature alcohol. For the
most part, it’s role is merely as a carrier. Rather than dissolving
it, you need to use a fine powdered grade of boric acid. Technical
grade is fine, if powdered. Then stirring it up off the bottom will
give you a nice suspension of the particles that will leave a nice
even coating on the work once burned off. Using a coarser grade of
grind is a problem. And note too that the boric acid and alcohol
won’t clean your work prior to soldering. Oils, grease, too much
oxide, etc, can act as a stop off, preventing the boric acid from
doing it’s job and properly coating the metal. Also, you don’t need
an extraordinarily thick layer of boric acid to remain after burning
off the alcohol. A thin frosty layer is enough. If you’ve got a thick
opaque white blanket of boric acid on the metal after burning off
the alcohol, you’ve got too much. It will tend to break up or flake
off or ball up in the thicker spots. Thinner layers work much better.
It doesn’t take an enormous amount to properly protect the gold or
diamonds (the two main things the protectant is used for).

Also note that the boric acid and alcohol dip is primarily used for
gold, or platinum (to protect diamonds, not to protect the metal,
which should not actually be coated) but not for silver. It doesn’t
work well on silver. The surface tension of silver is higher, and
will cause boric acid by itself, to behave as you describe, balling
up and pulling away from much of the surface, leaving it
unprotected. The solution is to use one of the more complex mixes
which contain something to handle that surface tension, ie a
surfactant, detergent, etc. One solution often discussed here (by me
and others) is Prips flux, a mix of boric acid, borax, and sodium
phosphate (tri sodium, di sodium, or mono sodium forms all work. The
trisodium, also known as TSP is often the easiest and cheapest to
get, as it’s widely used as an alkaline cleaning agent) In this mix,
which is 3 parts boric acid to 2 parts each of the others, dissolved
in water, the boric and borax are the protectant agents, while the
TSP acts as a wetting agent allowing the melting borax/boric acid to
properly form a congiguous film on the metal surface. It’s more
complex to use than the simple boric acid / alcohol dip used for
gold, but it works. Other similar commercial products are those like
Cupronil flux, which does the same as Prips, but is commercially
available, rather than being a “mix your own” product.

Hope that helps.
Peter Rowe

5

You need powdered boric acid. Pharmacies have it. I’m also told Roach
proof is 100% boric acid.

I ALWAYS kept a screw top on the boric acid, if left open the mixture
changed.

David Geller

6 
im having a bit of trouble getting this boric acid to desolve in
the denatured alcohol,

Most denatured alcohol is ethanol with some form of denaturing agent
added to it to make it toxic to drink. This is your main problem,
boric acid is not very soluble in ethanol. It is more soluble in
methanol which is what is used in commercial versions of this fire
coat. The drawback to methanol is it is significantly more toxic
than ethanol so you need more care in handling it.

James Binnion
James Binnion Metal Arts

7

Jason,

The reason it doesn’t dissolve is that the solution is saturated,
That is, the alcohol has absorbed all the boric acid it can and the
rest just drops to the bottom of the jar. that is what you want.

Jerry in Kodiak

8

Comment about keeping cap on is always sound.

The other day I was shifting a bottle of alcohol from one surface to
another. It slipped out of my hand and hit the floor. The sploosh
came straight up and hit my eye. Impressive and frightening. Good
thing it was only alcohol and not mixed with anything else.

Screw the cap on before moving. Will always remember this one.

Simone

9

Hi Jason,

Alcohol will not dissolve much borassic acid, you need to include
the suspended particles as well.

My jar always has a layer of un-dissolved borassic at the bottom. To
coat an item I hold it in tweezers and using the item I stir up the
jar till the particles are suspended.

When burning off I tilt the item this way and that so the drip will
coat the stones. If there is only a centre stone then I let the drip
hang on the centre. If there are shoulder stones then I run the drip
from one side to the other while burning so that the borassic dries
onto those stones.

Alastiar

10

Make sure the boric acid is very dry - putting it is an oven at a
low temperature might help with this. So far as I know, boric acid
just dissolves in alcohol; it doesn’t react with it to form something
else, so as long as the alcohol is cloudy, it should do it’s work. I
always have a thick boric acid paste left at the bottom of the
container.

Jamie
http://primitive.ganoksin.com

11

Jason:

The boric acid does not dissolve… it is not supposed to. It is in
suspension in the alcohol. I never have the “blotchy” issue. You
indicated you were swirling it up prior to dipping, perhaps you don’t
have enough boric acid in the alcohol??

Have you considered Pripp’s flux… there are “recipes” for it in the
archives. Personally, I find the boric acid in alcohol route to work
just fine for my needs, but Pripp’s flux will give you better
protection if you are applying a lot of heat over a longer period of
time. The downside to Pripp’s is you have to make it and it is a real
solution and has to be applied with an atomizer. You can buy premixed
Pripp’s, but I’ve never tried it.

Good Luck!

12

I’m not going to answer your question but I may resolve your
situation. What is the real situation? You need to firecoat but have
difficulty producing a useable liquid (or so you may think).

Here’s what I think of borax/alcohol. It has no place on a brightly
lit bench with a torch. When alky burns the flame is barely visible.
You have an open container what maybe 10 inches from the torch? If
you can barely see it burn how can you know its completely out? How
can you know you didn’t spill a little and its on fire right where
you’re going to put your hand? It can drip in little flamelets onto
the floor, got carpet? How can you know you won’t topple the jar
over and flood your work area or maybe your lap with nearly invisible
flames? Like your eyebrows? Wanna keep em? Mostly you won’t have a
real safety problem. All it takes is one time though. I had my one
time.

Borax spatters near the end of its burn. It fouls the bench and
leaves white dusty flecks all over the place. Benches get messy
enough without all that icky goo.

Why do people use borax? I think it must be some mythic, “tradition
for tradition’s sake”, “this is way it says in the book”, “everyone’s
doing it” …misguided folly. Why go thru all that crap when there
is an easily obtainable, cheap, better alternative? Someone else
mentioned atomized firecoat. I like Cupronil. That’s what you should
try.Its non-flammable, its very controllable, its neat. Learn to be
gentle when pressing the button, don’t flood it. I’m sure the
procedure is in the archives.

And I’m sure I’ll hear differently. Borax is an anachronism as far
as I’m concerned. I don’t see the point of using a system that not
only has its distinct disadvantages but is apparently very difficult
for you to use successfully.

I find it curious that in the jewelry industry, which is ever
changing, some things just tenaciously hang in there despite better
choices. Me, I’d rather just get on with it.

13

My recipe/2c

I use a ground glass, square apothecary jar. I fill it about an inch
from the top with reagent grade methyl alcohol that I buy at a
chemical supply house. To it I add too much boric acid powder (dust)
bought from the same chemical house. I say too much because I want a
supersaturated mixture. I let the boric acid settle to the bottom
and NEVER stir it.

In use: I dip whatever it is I’m going to solder into the mixture
and flame it.

Then I set it up as necessary for the soldering job, and using a
cheap little paintbrush, drip more of the mixture where I plan to
solder. That’s really pretty much all the flux I use. Sometimes with
sterling I have to use that green liquid commercial flux that I put
into a syringe with a needle ground dull on the belt sander. I can
place very tiny amounts with that setup.

Here in Tennessee we can buy needles OTC, but if you can’t in your
state go to a farmers coop.

14 
The boric acid does not dissolve... it is not supposed to.

It will if it is methanol but not in ethanol. I buy boric acid
dissolved in methanol from Otto Frei that works far better than
using the ethanol boric acid slurry. When burned off it leaves a fine
coat of boric acid on the whole piece. And there is no particulate
mess on the bottom.

James Binnion
James Binnion Metal Arts

15

Hey Neil,

I assume you mean boric acid not borax as borax is totally insoluble
in alcohol.

The main benefit of boric acid in alcohol (methanol) is it coats
very evenly and unlike water suspensions of flux which have
significant issues with surface tension and pull away from full
coverage. Also if it is methanol and boric acid you don’t get the
splattering as there are no particles in suspension as the boric acid
is dissolved in the alcohol like there will be in the vast majority
of ethanol-boric acid mixtures.

But I also use a cupronil equivalent for much of my soldering
(anything with silver, copper, red gold, nickel white etc) where the
greater protection it gives is necessary.

You are right that boric acid alcohol is a safety issue and probably
in many cases not an effective firecoat for work that is not yellow
gold.

Regards,

Jim

James Binnion
James Binnion Metal Arts

16 
Someone else mentioned atomized firecoat. I like Cupronil. That's
what you should try.Its non-flammable, its very controllable, its
neat.

Most of the time I use Magic Flame in alcohol as a dip. I don’t
dispute your safety concerns. Everything you say about alcohol flux
is true. It is a hazard, one among many, that needs to be managed. I
have a light over my soldering bench and turn that off to see when
the alcohol flame burns out. Sometimes I just wait until the alcohol
evaporates. Either way works.

I use Cupronil some of the time and would like to use it more often,
but your statement that it is controllable and neat doesn’t match my
experience with it. The spray goes around and beyond the pieces I
try to coat. I wind up with sticky residue on locking tweezers,
third-hands, soldering pads, etc. Maybe it is neat and I am not,
but… If Cupronil was a gel and could be dipped I would agree with
you and I’d use it exclusively.

Best wishes,
Neil A.

17

Boy did I get mail. Maybe I was a bit strident in the way I phrased
things but the scars in this pic are the result of a flaming
boric/alky spill some twenty years ago, and they have faded ALOT. I
was hardly a newb at that point, knew what I was doing by then but
you know Murphy’s Law. The Cyprus shaped burn particularly hurt like
a banshee.

1600×1200 89.5 KB

Up to that point I hadn’t had problems with the alky. I know though,
that given its discontinued use, I definitely will not get anymore
serious burns from it.

With viable alternatives available I can’t see taking the risk. If
any of you employ people and you tell them to do it this way…are
you really sure you wanna do that? Litigious society and all?

18 
Why do people use borax? I think it must be some mythic,
"tradition for tradition's sake", "this is way it says in the
book", "everyone's doing it".....misguided folly. Why go thru all
that crap when there is an easily obtainable, cheap, better
alternative? Someone else mentioned atomized firecoat. I like
Cupronil. That's what you should try.Its non-flammable, its very
controllable, its neat. Learn to be gentle when pressing the
button, don't flood it. I'm sure the procedure is in the archives.

Sorry,

I’ve got to disagree with you on this one. Borax is different than
boric acid. Borax will etch corundum when heated. Boric acid will not
(my experience) and it will fire-coat the metal pretty well. With
silver link chains…if I’m soldering a lot of links (only for my
daughter) I’ll dunk the whole chain and not need to use flux on the
individual links. A lot less messy.

Yes the denatured alcohol is dangerous because it burns clean and
clear but that’s why we use it. As for the methanol (added to
denature it) which is poisonous and can be absorbed through the skin
that’s not cool either but I thank the tax collectors for that health
hazard. You could use straight ethanol alcohol from a liquor store but
it costs much more.

I keep a jar on my bench closed at all times when not in
use…otherwise the boric acid would be all over the place and the
alcohol would evaporate quickly.

Mark

PS There are other fire-coats out there that I don’t use…Blue
Stuff… but it’s more expensive, is still flammable, still
evaporates, & I don’t know if it will etch corundum.

19

Neil,

I certainly understand why you are so strident. Boric/Alcohol in the
bench deserves extra precautions if it going to be used. I keep mine
in a Candle Glass Jar with a Locking-Lid, only opening the locking
lid to dip the metal, then relocking the lid before turning on the
torch. It is a square, squat container with double-stick tape on the
bottom to keep it from moving.

Perhaps this is overkill (and takes a little more time) not to have
the alcohol open when the torch is on, but my instructor had a burn
incident too. He taught me these precautions, and I follow them
religiously.

Regards,
Jamie

20 
Boy did I get mail. Maybe I was a bit strident in the way I
phrased things but the scars in this pic are the result of a
flaming boric/alky spill some twenty years ago, and they have faded
ALOT. I was hardly a newb at that point, knew what I was doing by
then but you know Murphy's Law. The Cyprus shaped burn particularly
hurt like a banshee.

A woman I took a jewelry making course from had a similar
experience… and similar scars. She knew what she was doing too,
but accidents happen.

The worst thing about it was the fact that the alcohol that has
soaked into your skin just keeps burning… the flames are difficult
to put out.

I agree with you… why take the risk when there are good
alternatives.

Rita
Mossy Twig Jewelry