I share a jewelry studio with others. Most of us work in silver, but
someone wants to work with aluminum. Once, when I took a class there
was an aluminum project & we had to use separate saw blades & files.
Is that because the aluminum is so soft & they will get clogged, or
are there other reasons as well. I know that it will contaminate
pickle - but is it harmful to other tools such as disc cutters &
rolling mills? Can particles remain & transfer to silver & then
contaminate the metal in the pickle? And while we’re on the subject
of aluminum - do you think that anodized aluminum is safe for
cooking? Is it just a coating, or does it actually change the
aluminum permanently? I thank all of you for your comments and
advise.
My instructor’s recommendation was not to work with aluminum. If I
chose to work with aluminum, I should have one set of tools for
silver, a separate set of tools for aluminum, and never mix the two.
I’ll be interested to read comments from other Orchid members.
Good luck.
Mary A
Chief Design Officer
Jewelry for the Journey
If you get some aluminum embedded in your silver or gold from saws,
files or work surfaces contaminated with aluminum and then heat it up
you will be in for a nasty surprise. It will melt into the surface of
the work and ruin it. So yes you should use separate tools and work
areas or be meticulous in cleaning up after working with aluminum.
I’d be concerned about stray Al particles eating into silver when
soldering, similar to lead. Do some tests, I tried and it didn’t but
it was just a quick test. Separate files since Al files have a
different cut. No real concerns about the pickle, you can’t really
solder Al so no need to pickle. And when anodizing you use an ~20%
sulphuric acid solution and some electricity. That 20% acid is also
an old school pickle. Anodizing is a surface effect (maybe a couple
of thousands of an inch thick if you try really hard) Just an
enhanced oxide layer which forms on the surface instantly any ways.
Initially porous so that you can dye it, then seal with boiling
water. Not sure about Al being safe for cooking but my 50+ year test
is still ongoing
contaminated with aluminum and then heat it up you will be in for a
nasty surprise. It will melt into the surface of the work and ruin
it.
What sort of damage does aluminium do to sterling silver? My
husband, who is a police officer, has just been sent back out into
the real world after five years in a desk job. As he’s previously had
a few expensive Maglite torches stolen (yes police officers actually
steal each others’ property!), he asked me to engrave (or rather
carve) his collar number on his aluminium bodied torch. I dutifully
carved his number into the body of the torch in four places using a
burr in my flex shaft, at my bench. I’m now worried as to what might
happen to my silver jewellery!
Is it possible to be specific about the damage? Thanks.
It will alloy with the silver and form a low melting point mess on
the surface that is hard and brittle due to the presence of aluminum
oxides and intermetallic compounds. It will most likely ruin the
piece as you would have to grind it all out to get rid of it and it
can eat quite a ways into the surface.
What sort of damage does aluminium do to sterling silver?
In case James doesn’t reply.
Because the aluminum has a much lower melting point than sterling it
melts early and starts forming alloys with the sterling in the local
area of the aluminum.
This effect causes deep pitting and gray areas (if I recall
correctly they are pretty hard) that are very difficult to remove,
and usually permanently damage the piece.
In my shop I use a great variety of metals including three types of
aluminum. I usually clean pieces ultrasonically before soldering and
haven’t had any problems. I never mix saw blades or files, but I do
mix burrs.
I use my burs with bees wax and they are all carbide. The ultrasonic
will remove anything that isn’t mechanically bonded to the
substrate. I am drawing from personal experience and believe that the
differences in the cutting process between files and saws, and burs
is what makes the difference.
I believe that files and saws will embed minute pieces of Aluminum
into the substrate very slightly below the surface in-part because
they don’t cut so cleanly (even new, they roll the chips into the
cut); the burs cut more like milling cutters, pushing the chips
ahead and taking any aluminum with it.
Without the benefit of an ultrasonic I would be extra careful, but
still a good cleaning with a brush should do. I bow to James if he
disagrees.
As a side note steel will not damage sterling, but will stain it,
until it is sanded or polished out.
Also as a side note, non of my burs come from jewelry supply but
rather industrial; I use burs from a company called Metal Removal
purchased from Rutland (http://www.shoprutlandtool.com/).
It will alloy with the silver and form a low melting point mess on
the surface that is hard and brittle due to the presence of
aluminum oxides and intermetallic compounds. It will most likely
ruin the piece as you would have to grind it all out to get rid of
it and it can eat quite a ways into the surface.
Yes, but before it can do that, the molten aluminum has to actually
contact the silver before they can start to alloy. That is more
difficult with aluminum than with, say, the case of tin or lead
contamination on the silver. The reason is the durable oxide film
that builds up on aluminum. Often, melting aluminum without careful
fluxing or other protecting atmosphere, will not manage to penetrate
it’s own oxide dross. Try melting some aluminum foil, and you’ll see
what I mean. It doesn’t much melt. Just crinkles into a mess, never
quite looking anything like a molten metal. Just for curiosity, I
tried it out tonight with a bit of scrap silver and some small bits
of aluminum laid on it. No flux or firecoat. Neutral to barely
reducing flame (oxy propane). The aluminum bits didn’t melt into the
silver. Stayed on top even though they clearly exceeded their melting
point. Their oxidation trumped their ability to mess of the silver if
had actually wet or alloyed with it. Tried it again with a coating of
handy flux. This time, some of the bits just foated on the flux.
Only one seemed to adhere to the metal, and it did rather scar it.
But this all is much less than I’d have gotten had these been scraps
of tin/lead solder or of pewter, where I’d expect most or all of the
bits to burn holes in the silver, or of bits of silver or gold on a
piece of platinum.
I conclude that while aluminum may indeed present a danger to the
precious metals, it seems to me of a rather lesser degree that some
other contaminates. And understanding the risk and taking precautions
seems sufficient. To illutrate, I cannot set up a seperate workbench
for platinum work only, so I work platinum and gold and silver all on
the same workbench, and often with the same tools. This indeed poses
a potential risk to the platinum. but knowing this, I’m simply
careful to be sure the platinum is clean before heating it. Usually
this means the ultrasonic or steam cleaners, and then heating is on
a sintered silica (Wesgo type) block which IS reserved just for
platinum work, and handled with carbide tipped soldering tweezers
which are also reserved for platinum work only. All in all, only a
modest amount of care and effort. While on occasion, I’ve still had
slipups, frankly, they’re very rare. Last time contamination caused
me any significant problems with a piece was something like 6 years
ago. Not too bad, overall… So I suggest care, but I’d say paranoia
is not warranted.
I agree that it is not as easy to melt aluminum into your work as
with tin or lead but all it takes is once to ruin your day. If you
have a good heavy flux coat it will alloy with the surface. I lost a
ring to aluminum contamination a couple of years ago. Made a nice
bright purple spot on the ring
Speaking from a few years experience, although from a vastly
different field of work, if at all possible a person should never
allow a set of tools used for one type of metal to become
contaminated with a different type of metal. The experience referred
to was while working at a major aircraft assembly plant that used
both aluminum and steel in the fabrication and assembly of the
aircraft. The welding department required any worker in that area to
keep a full set of files, file cards, drills, and any other small
tool that might be used and to keep the two sets of tools separate
from each other.
Thanks very much for the advice Dan. I’ll have a good clean-up. It’s
not occurred to me to ultrasonic metal before soldering and I must
admit I’m a little to impatient for that. As I don’t work with
aluminium (it was just a one-off), I’ll clean out my bench and tools
and hopefully avoid any problems. Thanks again.
I agree that it is not as easy to melt aluminum into your work as
with tin or lead but all it takes is once to ruin your day. If you
have a good heavy flux coat it will alloy with the surface. I lost
a ring to aluminum contamination a couple of years ago. Made a nice
bright purple spot on the ring :-(
Yup.
However, it occurs to me that if one can learn to control it, that
potentially decorative purple color might be used as an intentional
effect rather than a destructive one. Might be tricky to control
consistently, but…
However, it occurs to me that if one can learn to control it, that
potentially decorative purple color might be used as an intentional
effect rather than a destructive one. Might be tricky to control
consistently, but...
Making purple silver or gold alloys has been done and documented and
I can tell you from personal experience the results aren’t very
good. A purple coating can be achieved with great difficulty, though
very consistently once parameters are worked out, on sterling using
photo- chemistry.
About twenty years ago I produced product with a fairly full dark
purple surface layer by making the sterling (bracelets) photo-
reactive in complete darkness and then exposing them followed with
development and fixing.
The finished lasted about 15 years without very much polishing.
Heavy or frequent polishing would of course remove the coating very
quickly as it’s thickness is measured in nano-meters. Suitable for
spouses of smiths not their customers. Something lacquered for
display of course would work.
The bad news is I can’t remember the formula even though I was quite
a photo head at the time; it was definitely a Bromide formula, but I
can remember anything else.
However, it occurs to me that if one can learn to control it, that
potentially decorative purple color might be used as an
intentional effect rather than a destructive one.
I was thinking the same thing. Was this “purple spot” accident on
silver or gold? I was thinking it must be gold, as in the aluminiun/
gold purple gold alloy, but the thread was about silver so I wasn’t
sure. Either way, it could possibly produce some interesting effects
if done on purpose, as Peter says. Although as I understand it, such
an alloy is usually set as “stones” due to its hardness an lack of
workability so finishing such a patinated piece might prove rather
tricky - but texture is my new best friend!
I want to thank everyone for their input. I just became a member and have 0 experience. I spent a ton of money getting tools and different forms of silver and aluminum. I am so glad I read this article! I was smart enough to start practicing on the aluminum before touching the silver and this article probably saved me a few thousand dollars and many wasted hours, days, years! Thanks again!
