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Antifirescale Coatings


Does anyone have any strong feelings one way or another as to
whether boric acid/alcohol, Prips or commercial products like
Cupronil compare in terms of reducing firescale? Does one seem to
work better with gold vs. silver?

If anyone has been unable to locate boric acid at a pharmacy, you
can also find it at the grocery store or hardware store in the
insecticide section. It is sold as powdered roach killer. You should
be able to get a 1 pound container for $2-$3.00 US.

Cheers and thanks, -Mike

Mike Dibble
Black Horse Design
New Greyhound & Celtic Designs Now on Display!
10% of retail sales support rescues.

    Does anyone have any strong feelings one way or another as to
whether boric acid/alcohol, Prips or commercial products like
Cupronil compare in terms of reducing firescale? Does one seem to
work better with gold vs. silver? 

I have been using boric acid/alcohol for 20 years and find it the
easiest for gold, but I hate it on silver, I almost quit working
with silver until I discovered Cupronil, it takes a little longer to
apply but it works great. I have a few designs that I high polish
before soldering bezels, and all I have to do is a quick touchup
after using Cupronil.

Also I might be crazy (and some out there would agree) but I think
there is a difference between the denatured alcohol from the jewelry
supply/drug stores vs the hardware store. I have been told there is
none, but it burns different, it smells different and it seems to
have an oily residue. So for all you chemist out there what’s the
answer, maybe I’ve inhaled to many fumes, at least with the boric
acid around I don’t have roaches in my shop.

Best to all,
Bill Wismar


Hi Mike,

I work mostly with sterling and I just wanted to say I love Cupronil
for certain projects. On most stuff I use Prips for the convenience
but I’ve used boric acid and alcohol too. (I always leave the durned
lid off, prips evaporates a lot slower than alcohol.) But I
discovered Cupronil when I was soldering a gazillion domed hammered
discs doing production work for a designer. I have a pretty torch
happy so by the time I got rid of all the purple shadows the hammered
texture would be sort of soft and rounded. Using Cupronil does not
keep firescale away completely but it sure seems to make it softer,
or thinner or something. I could get rid of the ‘shadows’ and still
have most of the sharp hammered texture I started with. While I like
it as a firecoat, it’s a crummy flux, I still dab a little regular
flux right where the solder joint will be. Hope this is helpful!



Hi Bill;
I have never worked in gold, so I can’t speak from that
arena. I can though from silver. I used to use boric acid/alcohol,
coated about 2-3 times, on my pieces to try and prevent firescale,
and I had some success with it, but also many failures. I can
honestly say though since about two years ago when I started using a
prips formula given from one of our Orchidians, I never have
firescale. It is a thing of the past. Even when I make a large heavy
oval belt buckle and heat it till I’m afraid it will melt, no
firescale. The formula for this version of prips (not the commercial
one) is in the Orchids archives. If you have any difficulty finding
it, I would be glad to send it to you. Just look under the thread
"prips". I hope this helps, best wishes, John Barton


While I love the look of firescale free silver it is so hard to get,
nothing I tried seems to prevent it. I have decided that sterling
silver needs a new marketing angle. Explain to your customers that
part of the charm of sterling is the oxides. It gives it a grey
purple tone. I think this is also a selling angle as metals that
are produced to look like silver - base metal coated will not tarnish,
and look fake.


Hi Bill, I agree, the alcohol/boric acid works great for gold as an
anti-firescale treatment. And no, you’re not crazy, nor are you
imagining things regarding the difference in alcohol smells. You
just have a good nose! Recently I’ve been learning another archaic
trade, natural perfumery, and have researched alcohols rather
deeply. The ethyl alcohol you buy (anywhere) is denatured with any
of perhaps 100 chemicals, of synthetic and/or natural origin.
That’s what makes it stink and what makes it unpalatable, but it
doesn’t seem to affect what we need it for as jewelers. (For
perfume, however, I want the un-denatured stuff, 90%-plus prrof,
need an expensive license just to buy it, and then get to pay a
fortune for it, and again for its hazmat shipping.) – Elna in Berkeley,
nose atwitchin’


I’ve always just raised the fine silver on pieces when I’m done. But
recently that started getting harder to do with some of the mixed
materials I’ve been using. So a few weeks ago in the middle of the
night I decided to make some boric acid/alcohol stuff. Problem was I
didn’t have any denatured alcohol. So I mixed my boric acid with
Everclear that I had left over from the days when I drank
ocassionally. My understanding of denatured alcohol is that it is
made poisonous so that it can be sold in the hardware store, without
ID, on Sunday, etc. It also usually has a smell added to identify it
as poisonous. So I figured, Everclear is 95% alcohol. Surely it will
work, and it did. It seems to me that it could potentially be safer
to breathe the fumes since it is made to be drank, whereas denatured
alcohol is supposed to be poisonous. It also doesnt really have a
strong odor either which may be a selling point for some people. So,
am I crazy or does anyone else use Everclear also?

Kevin Ard


40 years ago I had an instructor that showed us the work of a
metalsmith that would peen tiny dimples into firescaled sterling and
then polish off the ridges to achieve a beautiful texture of light
dark pattern of surface treatment.
Done well this can add a new dimension to finish. Cary

am I crazy or does anyone else use Everclear also?

Well I have heard some great excuses for having a bottle of liquor
at ones bench, but this is the best. Just don’t set your bottle of
Coke right next to it.

Just a reply to add a little humor to our tedious jobs.

Best to all,
B. Wismar

am I crazy or does anyone else use Everclear also? 

OK I’ll bite! I’ve worked out that it’s booze, but what sort of
booze? Bourbon? Do you use it in your mouth torch? Or is it just for
pain relief? I haven’t seen it in an Australian bottleshop - but
then again I don’t get much past the the bargain boxes.

Al Heywood


Hi, Al- I know about this from my misspent youth, not through jewerly
or lapidary. Everclear is not bourbon- it is grain alcohol that is
about as pure as you can get it with a still- 190 proof or so.
Drinking it straight is ill-advised, and you don’t want to light a
cigarette around the stuff, either. It is most commonly used as a
component in punch by the college crowd, as it is not so easy to
detect that way and packs a serious wallop. This is the first time I
have heard of using everclear for anything except attitude
improvement :slight_smile:

Lee Einer,
Phoenix, AZ


Allen; Everclear is a brand name of just straight 100 proof ethanol.
Grain alcohol. Common here as a component of childish concoctions in
fraternity houses and college keg parties. Can be a wicked addition
to the normal drink of an unsuspecting victim. In trade practice
here denatured alcohol used to be adulterated ethanol, as several
posters have stated, but now it is actually usually
methanol. Tom


Hi Al,

 OK I'll bite!  I've worked out that it's booze, but what sort of

Everclear is as close as your can get to pure alcohol in a retail
liquor store in teh US. It’s 190 proof, 95% pure. It’s perfectly
clear & stays that way until it’s mixed with something else in a



Everclear is also called grain alcohol, about the strongest thing
you can buy to drink here in the states, although I can’t imagine
doing so. I’m glad to hear that someone found a good use for the
stuff, maybe I’ll try it sometime instead of denatured alcohol.


Al, Everclear is the ultimate fire-water – it’s 190 proof grain
alcohol, and it burns great. I’ve used it, or the equivalent, mixed
with boric acid, to good effect. If your help gets into it, at least
it won’t poison them like denatured alcohol would.