Fabricating Pewter?
ban...@my-deja.com
I just recently learned that (lead-free) Pewter sheet is commercially
available. I've never thought about fabricating with pewter before...
What is the best solder to use? Do you need to use flux? Can you
pickle? Any advice is appreciated!
Thanks,
Banjo
Sent via Deja.com http://www.deja.com/
Before you buy.
Peter W. Rowe
>>I just recently learned that (lead-free) Pewter sheet is commercially
>>available. I've never thought about fabricating with pewter before...
>>What is the best solder to use? Do you need to use flux? Can you
>>pickle? Any advice is appreciated!
Commercially available pewter is essentially pure tin, with a little antimony
and copper added to increase hardness. It's quite nice to fabricate, makes a
great model making metal, but is very different to work with than, say, sterling
or gold.
One of the biggest differences, aside from it's very low melting point, is that
it does not work harden. In fact, the more you work it, the softer it becomes.
In essence, you can think of it as though room temperature is it's annealing
temperature, so working it simply causes the grain refinement that normally
needs work hardening and annealing with silver or gold. You cannot harden
pewter, other than simply casting it (the as-cast hardness is as hard as it
gets. Which isn't very hard) so when making jewelry or other objects, you must
keep in mind that the metal is soft and easily deformed, bent, worn out, etc.
Design the piece accordingly.
In soldering, you use low melting "soft" solders (solders like Stay Brite, a
tin/silver alloy, work very well, and there are others too. Use them with their
own flux, or any soft solder fluxes such as used with tin/lead solders. You
don't need to pickle, since there is no surface oxidation problem. Just wash
flux residues off with water. If it's a bit discolored, a little very fine
steel wool fixes that.
It does not transmit heat well, so soldering large areas or seams, which might
make you want to heat the whole thing, can be difficult. Unlike with silver or
gold, it's OK to just flow a little area, then move onto the next. Soft gentle
flames, such as that from the smallest tip on a prestolite or smith handi heat
torch, work very well. So do hotter, but very small flames, like smaller tips
on a little torch. Gently brush the pewter, then pull away. Don't actually
hold the flame on the metal for more than a couple seconds at a time, or you'll
melt more than the solder.
This poor thermal conductivity, though, makes it easy to fuse/weld pewter. Make
the seam a wider gap, maybe a V joint, almost closed at the bottom, but wide at
the top. Place chips of pewter on the gap, and one at a time, hit just the
chips with a small flame. (don't forget the flux). As each chip slumps and
fuses into the seam, add another chip and continue. Be careful not to let the
whole piece get so hot things other than the chips start to melt. Once the
whole seam is finished, place it on a steel surface and hammer the seam, forging
the bead down into the metal, but not quite all the way. This makes the metal
more uniform in hardness, and then, after you've file the rest of the bead away,
you'll have a continuous piece of pewter with no discernable seam at all.
Because you can thus weld sheet metal to a condition as good as new sheet metal,
many types of shaping become practical that are not, in silver. For example,
Matthew Hollern, an artist I went to grad school with, and who now teaches at
the Cleveland institute of Art, in school was doing very large sculptural
hollowware pieces. he could do things like construct six foot long spiculums (a
tapered tube, as though you wrapped metal around a tapered mandrel) from
multiple sections of tapered tube, to get a long form tapering from maybe
several inches wide at one end, to very little at the other. This could then be
bent into complex fanciful forms, much like some of the forms one associates
with solid wrought iron work from, say, Albert Paley's earlier work. But the
bending is done not by actually bending the spiculum much, but by cutting
repeated closely spaced wedge shaped sections out of the tube, bending (now just
the outside wall is bent) to close up the gap, and welding it shut. Once filed
up, and maybe lightly planished, you could not see he'd ever cut it, and the
resulting forms were wonderfully sinuous and smooth curves that would have been
much more time consuming and difficult to achieve in harder metals like silver.
Or take the work of Fred Fenster (who taught me silversmithing and jewelry, back
at the university of Wisconsin in the early 70s, and later, taught Matthew
Hollern how to work pewter too.) Fred is very well known for his work in
pewter, and some of his most striking hollowware forms include wonderful creases
and spirals in the raised forms. Looks very tricky. but with pewter, often
they are not actually raised, but made from sheet metal, scored, and after
bending into a cylinder or tapered cylinder, simply pressing the right places to
cause the scores to bend only gets the fancy forms. After soldering up the
scores, no clear evidence of how the shape was made remains.
There are a couple other points to make with pewter. One is the critical advice
to be very careful not to contaminate the work areas you use for silver or gold
(etc) with pewter. small bits, even filings, of pewter, that are in contact
with your silver or gold when you anneal or solder it, will burn right through
the silver, making pits that are deep and difficult to repair. You should
reserve separate tools, (especially files) and preferably, a whole separate
workbench, for working with pewter, or you'll find that your silver and gold
work suddenly starts giving you major problems due to the pewter contamination.
Another point to remember is that because of pewter's softness, you must use
thicker metal for a part than you'd use in silver or gold. Considerably
thicker. And some ideas just aren't workable. If you wish to set stones in
pewter, for example, forget about prongs in most situations. They just won't
hold. Remember too, that pewter is soft enough that it will rub off on skin.
While it's not toxic the way lead is, a ring made of pewter will tend to leave a
discolored mark on the skin. But given pewter's softness, a ring made of it
might be somewhat less than a bright idea in any case, except for the heaviest
and simplest designs. You can do it if you want, but consider carefully the
issues of durability.
Also, because of pewter's softness, a high polished finish is often considered
pretty impractical. You can do it, but don't expect it to hold up. Most pewter
smiths use a softer finish, such as filed finishes, satin wheels, scotch bright
abrasive pads, or steel wool, to give the metal a nice sheen, but not a high
polish. If you wish to oxidize it, dilute nitric acid gives a nice charcoal
black, which you then can highlight again with steel wool, or other polishing
method.
Hope this helps.
Peter Rowe
ban...@my-deja.com
What a great response. I really appreciate the way you spread
knowledge.