| Contenuto dell'articolo |
- From johnmenc@optonline.net Tue Sep 11 13:36:37 2012
Return-Path: <johnmenc@optonline.net>
X-Sender: johnmenc@optonline.net
X-Apparently-To: colonial-coins@yahoogroups.com
X-Received: (qmail 66201 invoked from network); 11 Sep 2012 20:36:37 -0000
X-Received: from unknown (98.137.35.160)
by m2.grp.sp2.yahoo.com with QMQP; 11 Sep 2012 20:36:37 -0000
X-Received: from unknown (HELO ng10-ip2.bullet.mail.bf1.yahoo.com) (98.139.165.78)
by mta4.grp.sp2.yahoo.com with SMTP; 11 Sep 2012 20:36:37 -0000
X-Received: from [98.139.164.124] by ng10.bullet.mail.bf1.yahoo.com with NNFMP; 11 Sep 2012 20:36:36 -0000
X-Received: from [98.137.34.155] by tg5.bullet.mail.bf1.yahoo.com with NNFMP; 11 Sep 2012 20:36:36 -0000
Date: Tue, 11 Sep 2012 20:36:36 -0000
To: colonial-coins@yahoogroups.com
Message-ID: <k2o7ck+lv2e@eGroups.com>
In-Reply-To: <k2o5e0+49vv@eGroups.com>
User-Agent: eGroups-EW/0.82
MIME-Version: 1.0
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: quoted-printable
X-Mailer: Yahoo Groups Message Poster
X-Yahoo-Newman-Property: groups-compose
X-Originating-IP: 96.56.209.230
X-eGroups-Msg-Info: 2:3:4:0:0
X-Yahoo-Post-IP: 96.56.209.230
From: "colonial_john_c4" <johnmenc@optonline.net>
Subject: Re: Wnuck Coin - 1771 GIII Cast (GH counterstamp)
X-Yahoo-Group-Post: member; u=111282553; y=q22gTw-0Omi_n7xzG95ZYbBTtDFL0LwXTFW9DvG94VbyV_G4O4zvZTeGpQ
X-Yahoo-Profile: colonial_john_c4
OK. Will return it after the analysis but then will cut it up to compare bo=
th inner cores of this piece to the 18thC cast. Most casts seem to follow s=
ome form of an empirical formula using lead and either tin or zinc in certa=
in proportions. This very high zinc and very low lead is an anomaly in my o=
pinion. The same holds true for Ag/Au - Hg amalgams generally over a quarte=
rnary type alloy of fixed proportions. But this is for another discussion <=
BG>. These large forgery manufactories I believe were very well skilled ind=
ividuals that knew how to mix metals for the proper end products (in most c=
ases).
As a favor I will throw another THOUSAND at your collection of CC2R's <NVBG=
>.
JPL=20
--- In colonial-coins@yahoogroups.com, "coinrarities" <dave@...> wrote:
>
> Hi All:
>=20
> John -- thanks for analyzing that cast cft halfpenny. If it will help yo=
ur research, you can photo it, cut it up, clean it, melt it -- whatever. I=
have another.
>=20
> You see -- I know the forger personally. He's quite a good looking, inte=
lligent fellow.
>=20
> OK -- I'll 'fess up. It was me. As a part of a multi-day Colonial Coin =
seminar at Colonial Williamsburg (I think it was right after the ANA in Bal=
timore that year), one of the things they had us do was cast our own counte=
rfeit British halfpennies. They took some scrap metal of the period that w=
as lying around (bits of copper barrel hoops, etc.) with no formula or rhym=
e or reason for the mix of metals. Then they put it in a crucible and -- u=
sing a bellows to get the fire really, really hot -- melted that scrap meta=
l.
>=20
> They then poured it into the mold and made a "tree" with perhaps 20 cast =
coins on it. they then snapped off the coins and handed them to the student=
s and told us to file down the casting sprues. That filing took about 10 m=
inutes per coin.
>=20
> Everything was done using period tools.=20
>=20
> The coins rang pretty well, and looked pretty legit (except they were fre=
sh pink in color). I took my two halfpennies and put them in my car's cuph=
older where I promptly forgot about them for a few months. By the time I f=
ound them again they had corroded a bit from having some diet coke spilled =
onto them a few times (!). I examined them again; they looked pretty darn =
legit to me. That was the day I stopped collecting cast cfts.
>=20
>=20
> John -- feel free to use this background info however you see fit.
>=20
> Dave W.
>=20
>=20
> --- In colonial-coins@yahoogroups.com, "colonial_john_c4" <johnmenc@> wro=
te:
> >
> > When you look at the coin I doubt anyone can say this cast was made som=
etime this year from its appearance and edge features. I may use this coin =
in the Ryder 40 study to compare it to the 1754 GII cast which was cut up a=
nd polished as a 18thC cast standard. For this coin since Wnuck does not wa=
nt it cut up we will look at the surface only and compare to see if there a=
re any differences ... Surface XRF analysis yielded: Copper (79.4%), Zinc (=
19.55%), Tin (0.75%), Iron (0.11%), Lead (0.09%), Indium (0.03%), Gallium (=
0.02%), Palladium (0.009%) and Iridium (0.00001%). I have yet to see a GII =
cast of the 18thC that did not have a good amount of lead say 0.5% or highe=
r? This work group that D.W. and F.Z. attended could have easily added lead=
and then even surface XRF would suggest its 18thC ... I remember D.W. tell=
ing me these were made primarily from melting Lincoln Cents and other? item=
s which seems to be the case with this very high zinc ... I recently dated =
a Lincoln Cent N.D. lamination peel error to a specific striking period ba=
sed on its copper/tin/zinc readings ... the very low lead (0.09%) and very =
high zinc (19.55%) tells me something is wrong here after examining about s=
ix other cast pieces and remembering the Mossman/Smith cast paper findings =
... but a good forger would get the FORMULA right. All I can say Dan Freidu=
s is lets see what the SEM has to say on the surface between D.W.'s 21stC c=
ast and the 1754 GII cast. HMMM ... if Ryder 40 had an empirical formula of=
a cast I guess you could throw in the towel ... I see no point in asking D=
.W. permission to cut up his souvenier ... but Dr. Anderhalt will compare t=
he surfaces and report differences in these two pieces ... after seeing thi=
s operation D.W. sold all his casts in his collection ... I guess if you do=
not have a $100,000 XRF device in your back pocket things could get confus=
ing ... I agree ...
> >=20
> > JPL
> >
>
|
|---|
| URL di origine |
|
|---|
| Data di pubblicazione |
|
|---|
| Volume |
|
|---|
