Was: Melting gold
Dear Leonid
I have bought your DVD and defnitely forging has improved the
quality of my jewelry a lot with a much longer lasting polished
surface. Would like to know more about forging in jewelry do you know
any books about this technique, different kind of hammmers etc…)
Thks again
best
nathalie
This is not a new debate. To forge or not to forge has been around for many years. Forging improves crystalline structure.
Well, not to get into a debate, but I’d like to read some scientific
literature on this alleged fact.
Paf
I’m mentally not too awake right now. So I don’t remember
references. Forging aligns the metal crrystals. This makes the metal
tougher. I’ll look up the references later.
John
Well, not to get into a debate, but I'd like to read some scientific literature on this alleged fact.
Google will give you both practical and scientific references with a
search on ‘forging grain structure’ or similar. I expect most any
metallurgy text will discuss it.
Al Balmer
Pine City, NY
I have bought your DVD and defnitely forging has improved the quality of my jewelry a lot with a much longer lasting polished surface. Would like to know more about forging in jewelry do you know any books about this technique, different kind of hammmers etc.)
Regretfully, I am not aware of any books teaching forging to
goldsmith. The only source of is literature on
decorative ironwork. Not every technique is adaptable to precious
metals, but a lot are. We have blacksmiths here, so someone will give
advise on educational material.
Leonid Surpin
Well, not to get into a debate, but I'd like to read some scientific literature on this alleged fact.
It is a fact. A good starting point would be Mark Grimwade’s book
“Introduction To Precious Metals”
http://www.ganoksin.com/jewelry-books/us/product/01929565305.htm
Mark is a metallurgist who among his other qualifications is that he
is a metallurgical consultant to the Worshipful Company of
Goldsmiths, and a consultant to the World Gold Council. Another
essential book would be Dr. Erhard Brephol’s “Theory and Practice of
Goldsmithing”
Chapter 4: Handling Metals, of Dr. Brephols book has a most relevant
statement in reference to this discussion. In the section on rolling
he states "Before being rolled into sheet a cast ingot must be
prepared by systematic, heavy forging. This will break up the
crystals, which, after annealing, will be in the best condition for
rolling. Only after the metal has been thoroughly compressed and
prepared with annealings should it be rolled to its intended
thickness. Though this appears to be an additional step don’t shy
away from the preliminary forging. It will significantly improve the
quality of the sheet and wire being made.
Both Brephol and Grimwade describe why the cast structure is not
desirable as a starting point for rolling in depth. To be brief the
crystal structure is neither chemically uniform nor is it of an
equiaxed small grain structure. Both of these issues can lead to
problems when rolling and deforming the ingot as Leonid has pointed
out.
Both of these books should be in every serious
metalsmith/goldsmith’s library.
James Binnion
James Binnion Metal Arts
Well, not to get into a debate, but I'd like to read some scientific literature on this alleged fact.
Sure I can help you there.
If you can borrow a copy of Mark Grimwade’s book “Introduction to
Precious Metals”, Chapter 10, page 81 goes into the effects of cold
working on microstructure. In his example his ingot has a consistent
grain size, so the example isn’t depicting an ingot created in a
steel mould.
I have other books that show the effects of hot forging on the grain
structure of steel.
Regards Charles A.
I don’t know much of the science myself, but you could try Mark
Grimwade’s “Introduction to Precious Metals” or “Metallography and
Microstructure of Ancient Metals” by David A Scott. The latter is
available for free, and I can send you a PDF if you can’t find it
online. The crystal structure of metals is pretty key to modern
metallurgy, and I don’t think there is any actual controversey about
it.
Jamie Hall -
primitivemethod.org
Many years ago there was a bullion dealers in London that used to
make their own stock. (They still exist in a small way but only as
scrap dealers) I noticed sometimes that when you sawed their sheet
silver that it was easier to saw in one direction than at right
angles, ie like a piece of wood. I assumed that it had been rolled
much more in one direction that the other and that the grains were
very elongated. It was quite noticeable under the saw, but there was
nothing visible. Just an observation.
Tim Blades
Some references regarding grain/crystal structure in metals:
http://www.ganoksin.com/gnkurl/ep7zcw
http://www.ganoksin.com/gnkurl/ep7zcv
John
Google will give you both practical and scientific references with a search on 'forging grain structure' or similar. I expect most any metallurgy text will discuss it.
Does it discuss forging VERSES milling? 'Cause I’m thinking it’s
pretty much the same. On a similar note, I’ve never had much luck
crossmilling without annealing in between. Metal cracks.
Google will give you both practical and scientific references with a search on 'forging grain structure' or similar. I expect most any metallurgy text will discuss it. Does it discuss forging VERSES milling?
Perhaps not, but that wasn’t the issue. The doubts you expressed
were as to whether forging improves crystalline structure.
Al Balmer
Pine City, NY
Perhaps not, but that wasn't the issue. The doubts you expressed were as to whether forging improves crystalline structure.
As Leonid and others already mentioned before,jewelry becomes harder
by fact and therefore longer lasting. Isn’t that enough to prove it?
Have fun and enjoy
Pedro