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Casting


#1

Ok everybody… Listen up cause I have a good one for you all…
It seems as though a freind of mine has stumbled upon someone who i might
have to consider some sort of God… Firts let me tell everyone that I have
been a jeweler for eight yearsnow and I have been doing design and casting
work for about four of those eight years. Now I know for a fact( or now what I
thought was fact) that in any kind of lost wax casting method used weather it
be centifical or vacum casting, you would normaly burn out for a good healthy
8 hours minimum, to get the best results. Well here is why this guy must be
some kind of God… My freind says he can give a wax model to this guy at 10
oclock Saturday moring and he will have it back in a perfect casting by 12
oclock noon the same day… If anyone with any knowledge of casting knows how
to pour investment and burn out then pour within a 2 hour time period… please
let me know. I don’t know about anybody else but my investment takes a minimum
of an hour before I would even think about putting it the oven… Is there
another way to burn out and cast other than Vacum and Centrifical??? And I
know a little about steaming the wax out but you can’t steam out carving
wax… Anyone… please comment I would love to know weather this person
really is a God… I doubt it highly…
Thank you
Marc Williams


#2

Ok everybody… Listen up cause I have a good one for you all…
It seems as though a freind of mine has stumbled upon someone who i might
have to consider some sort of God… Firts let me tell everyone that I have
been a jeweler for eight yearsnow and I have been doing design and casting
work for about four of those eight years. Now I know for a fact( or now what I
thought was fact) that in any kind of lost wax casting method used weather it
be centifical or vacum casting, you would normaly burn out for a good healthy
8 hours minimum, to get the best results. Well here is why this guy must be
some kind of God… My freind says he can give a wax model to this guy at 10
oclock Saturday moring and he will have it back in a perfect casting by 12
oclock noon the same day…

It’s easy. Use small flasks. Investment can go into the oven in about 15
minutes. It actually sets up in 9, I believe. I put it into my Neycraft and
crank it up to 6 1/2. In less then an hour, the temperature will be about
1500. Open the door to let the oven temperature drop to about 800 degrees.
The flask interior will still be too hot. Close the door and let the
temperature even out. Open the door again if necessary. Two hours is a good
overall time. I’m going to do one of these today. Yesterday, I burned a
flask out for 12 hours. Overnight. Cooking them pronto just requires small
flasks. Two inch or less. With large flasks, any remaining water in the
flask comes to a boil and can break up the investment. Go ahead. Try it.
Hey! Maybe that’s why my page is called A God Among Goldsmiths!

http://www.knight-hub.com/manmtndense/bhh3.htm
e-mail: @Bruce_Holmgrain
snail mail: POB 7072, McLean, VA 22106-7972, U.S.A.


#3

I’ve been fast casting for years. It works well with injection wax, but
carving wax can give you steam erosion problems. I mix the investment a
little thicker than usual, and let it set for 15 minutes. I put it in
the oven on turn the oven on high. As soon as the flask stops smoking I
cast. This way I can sometimes (depending on the oven heat up speed) get
a casting in less than an hour! This technique works well with stones
cast in place because the stones don’t burn this way. Try it, it works!

Good luck.

Jeffrey Everett

Thomas Williams wrote:

Ok everybody… Listen up cause I have a good one for you all…
It seems as though a freind of mine has stumbled upon someone who i might
have to consider some sort of God… Firts let me tell everyone that I have
been a jeweler for eight yearsnow and I have been doing design and casting
work for about four of those eight years. Now I know for a fact( or now what I
thought was fact) that in any kind of lost wax casting method used weather it
be centifical or vacum casting, you would normaly burn out for a good healthy
8 hours minimum, to get the best results. Well here is why this guy must be
some kind of God… My freind says he can give a wax model to this guy at 10
oclock Saturday moring and he will have it back in a perfect casting by 12
oclock noon the same day… If anyone with any knowledge of casting knows how
to pour investment and burn out then pour within a 2 hour time period… please
let me know. I don’t know about anybody else but my investment takes a minimum
of an hour before I would even think about putting it the oven… Is there
another way to burn out and cast other than Vacum and Centrifical??? And I
know a little about steaming the wax out but you can’t steam out carving
wax… Anyone… please comment I would love to know weather this person
really is a God… I doubt it highly…
Thank you
Marc Williams

orchid@ganoksin.com

Handmade 18K and platinum gemstone jewelry. Fine die
and mold engraving. Diamond setting. Class rings/pins.
25 years experience in the jewelry trade. 515-472-9830


#4

I’m now left to wonder at what flask temperature both of you are actually
pouring at… And are the castings porosity free? How about thin castings are
they coming out ok? this all seems to risky since most my things are one of a
kind peices… I do however do a few production line. I don’t beleive this can
possibly be fool proof… Maybee someday I will try it and see for myslef. I
have problems with porosity once in a while with a full 8 hour burnout. I
can’t imagine there would be no porosity with a 2 hour or less cylcle… Hmmmm
this is interesting…
Marc…From: owner-orchid@proteus.imagiware.com on behalf of Bruce Holmgrain
Sent: Tuesday, August 20, 1996 8:22 AM
To: orchid@ganoksin.com
Subject: Re: Casting

Ok everybody… Listen up cause I have a good one for you all…
It seems as though a freind of mine has stumbled upon someone who i might
have to consider some sort of God… Firts let me tell everyone that I have
been a jeweler for eight yearsnow and I have been doing design and casting
work for about four of those eight years. Now I know for a fact( or now what
I
thought was fact) that in any kind of lost wax casting method used weather it

be centifical or vacum casting, you would normaly burn out for a good healthy

8 hours minimum, to get the best results. Well here is why this guy must be
some kind of God… My freind says he can give a wax model to this guy at 10
oclock Saturday moring and he will have it back in a perfect casting by 12
oclock noon the same day…

It’s easy. Use small flasks. Investment can go into the oven in about 15
minutes. It actually sets up in 9, I believe. I put it into my Neycraft and
crank it up to 6 1/2. In less then an hour, the temperature will be about
1500. Open the door to let the oven temperature drop to about 800 degrees.
The flask interior will still be too hot. Close the door and let the
temperature even out. Open the door again if necessary. Two hours is a good
overall time. I’m going to do one of these today. Yesterday, I burned a
flask out for 12 hours. Overnight. Cooking them pronto just requires small
flasks. Two inch or less. With large flasks, any remaining water in the
flask comes to a boil and can break up the investment. Go ahead. Try it.
Hey! Maybe that’s why my page is called A God Among Goldsmiths!

http://www.knight-hub.com/manmtndense/bhh3.htm
e-mail: manmountaindense@knight-hub.com
snail mail: POB 7072, McLean, VA 22106-7972, U.S.A.

procedures


#5

I’m now left to wonder at what flask temperature both of you are actually
pouring at…

I would estimate the center of the 1 1/2" x 2" flask is 900 degrees when
I cast. It could be a thousand, but I’m careful to differentiate between
heavy castings and thin castings. The metal alloy you use makes a large
difference as well. If you are using silicon additive alloys, you need
to superheat both the flask and the metal to avoid porosity. If you are
using the old standard yellow gold alloys you’ll want to pour the metal
at the lowest flask and metal temperatures to avoid porosity. Annnnd,
the spruing is fairly critical. I say fairly because I’ve seen come
casters get great results using single sprues, where I would have use
two or three at least.

And are the castings porosity free? How about thin castings are

they coming out ok?

Yes, my casting are almost always prosity free. Porosity comes from
several causes. Improper spruing causes shrinkage porositiy, otherwise
known as hot-tear porosity. Tiny crevices, pits, hidden bubbles, and
holes in the wax leave tiny investment burs, flashing, fins and spikes
that break off when the metal flows in and generate sulphur dioxide gas
porosity. Bits of broken and loose investment from an unclean sprue base
and sprue as well as crud on the stirring rod contaminates the gold
possibly causing inclusions in the casting. Then, on top of all that,
you have cupric oxide porosity from burnt copper in the alloy, plus the
types of problems mentioned in the previous paragraph. But wait, there’s
more! hee hee another time…

this all seems to risky since most my things are one of a

kind peices…

When I’m fast casting one of a kind pieces carved from hard wax, I use a
very thick investment slurry, and heat the oven more slowly, up to about
1300, then cool it to casting temperature, about a 4 hour process. I
have successfuly done very quick burnouts with carving wax, but when
I’ve put 4 or 6 or 20 hours into a wax, I don’t take chances! I have a
friend that makes RTV molds of all his waxes before he casts them, a
good practice that I don’t have time for.

I

have problems with porosity once in a while with a full 8 hour burnout. I
can’t imagine there would be no porosity with a 2 hour or less cylcle…
I don’t think the burnout time has any bearing on your porosity
problems. If you are using small flasks, the heat will penetrate within
about 20 or 30 minutes to the core of the flask and the wax carbon
should leave the flask as carbon monoxide. If you were burning out
photopolymer models, I could understand it, I use about a minimum 12
hour cycle with most of the time spent at 1350, otherwise I have unburnt
ash ruining the surface of the casting.

Hmmmm

this is interesting…

Yes, isn’t it? :slight_smile:

Handmade 18K and platinum gemstone jewelry. Fine die
and mold engraving. Diamond setting. Class rings/pins.
25 years experience in the jewelry trade. 515-472-9830


#6

I’m now left to wonder at what flask temperature both of you are actually
pouring at… And are the castings porosity free? How about thin castings are
they coming out ok? this all seems to risky since most my things are one of a
kind peices… I do however do a few production line. I don’t beleive this can
possibly be fool proof… Maybee someday I will try it and see for myslef. I
have problems with porosity once in a while with a full 8 hour burnout. I
can’t imagine there would be no porosity with a 2 hour or less cylcle… Hmmmm
this is interesting…
Marc…

I’ll get behind just about everything that other guy is sayig. I try to cast
somewhere between 800 and 1000 degrees. One thing I might add that I don’t
think that he mentioned, is turbulence. Call it an ideosyncracy, but I try
to avoid turbulence ond vibration during a pour.
When I get a bad casting, it’s usually because I have tried to shortcut the
system in another way. Scrap metal can produce real problems.

http://www.knight-hub.com/manmtndense/bhh3.htm
e-mail: @Bruce_Holmgrain
snail mail: POB 7072, McLean, VA 22106-7972, U.S.A.


#7

Attetntion Jeff and Bruce… Both of you sound like you are very knowledgable
and I think I could learn alot from your tips… Is there anyway of
contacting either of you? And where is it that you guys are from??? I am from
Pennsylvania near the Scranton area…I don’t suppose either of you guys do
any casting seminars… Do you? THanks for your responses and keep em’
coming…
Marc WilliamsFrom: owner-orchid@proteus.imagiware.com on behalf of Jeffrey Everett
Sent: Tuesday, August 20, 1996 9:21 PM
To: orchid@ganoksin.com
Subject: Re: Casting

I’m now left to wonder at what flask temperature both of you are actually
pouring at…

I would estimate the center of the 1 1/2" x 2" flask is 900 degrees when
I cast. It could be a thousand, but I’m careful to differentiate between
heavy castings and thin castings. The metal alloy you use makes a large
difference as well. If you are using silicon additive alloys, you need
to superheat both the flask and the metal to avoid porosity. If you are
using the old standard yellow gold alloys you’ll want to pour the metal
at the lowest flask and metal temperatures to avoid porosity. Annnnd,
the spruing is fairly critical. I say fairly because I’ve seen come
casters get great results using single sprues, where I would have use
two or three at least.

And are the castings porosity free? How about thin castings are

they coming out ok?

Yes, my casting are almost always prosity free. Porosity comes from
several causes. Improper spruing causes shrinkage porositiy, otherwise
known as hot-tear porosity. Tiny crevices, pits, hidden bubbles, and
holes in the wax leave tiny investment burs, flashing, fins and spikes
that break off when the metal flows in and generate sulphur dioxide gas
porosity. Bits of broken and loose investment from an unclean sprue base
and sprue as well as crud on the stirring rod contaminates the gold
possibly causing inclusions in the casting. Then, on top of all that,
you have cupric oxide porosity from burnt copper in the alloy, plus the
types of problems mentioned in the previous paragraph. But wait, there’s
more! hee hee another time…

this all seems to risky since most my things are one of a

kind peices…

When I’m fast casting one of a kind pieces carved from hard wax, I use a
very thick investment slurry, and heat the oven more slowly, up to about
1300, then cool it to casting temperature, about a 4 hour process. I
have successfuly done very quick burnouts with carving wax, but when
I’ve put 4 or 6 or 20 hours into a wax, I don’t take chances! I have a
friend that makes RTV molds of all his waxes before he casts them, a
good practice that I don’t have time for.

I

have problems with porosity once in a while with a full 8 hour burnout. I
can’t imagine there would be no porosity with a 2 hour or less cylcle…
I don’t think the burnout time has any bearing on your porosity
problems. If you are using small flasks, the heat will penetrate within
about 20 or 30 minutes to the core of the flask and the wax carbon
should leave the flask as carbon monoxide. If you were burning out
photopolymer models, I could understand it, I use about a minimum 12
hour cycle with most of the time spent at 1350, otherwise I have unburnt
ash ruining the surface of the casting.

Hmmmm

this is interesting…

Yes, isn’t it? :slight_smile:

Handmade 18K and platinum gemstone jewelry. Fine die
and mold engraving. Diamond setting. Class rings/pins.
25 years experience in the jewelry trade. 515-472-9830

procedures


#8

Attetntion Jeff and Bruce… Both of you sound like you are very knowledgable
and I think I could learn alot from your tips… Is there anyway of
contacting either of you? And where is it that you guys are from??? I am from
Pennsylvania near the Scranton area…I don’t suppose either of you guys do
any casting seminars… Do you? THanks for your responses and keep em’
coming…

I don’t teach unless it’s an apprentice. I am in the Washington, D.C. area
in case you want to look me up sometime. I’ve also got a phone # on my web page.

http://www.knight-hub.com/manmtndense/bhh3.htm
e-mail: @Bruce_Holmgrain
snail mail: POB 7072, McLean, VA 22106-7972, U.S.A.


#9

Marc

If I were you, I’d get every book I could find on casting precious
metals. Get the Santa Fe Symposium books published by Rio Grande. Talk
with every caster you know. The knowledge comes over a period of years
and thousands of castings. Call Mark at PM West in L.A. and ask him
about porosity, and ask him for on hot water investment
mixing. And learn about the particular alloy you’re casting, talk to the
manufacturer of the particular alloy. Call the manufacturer and ask them
every single question you’ve ever had about their alloy. Some of the
best I ever received came from the metalurgists that
designed the gold I cast. Did you know there are special alloys for
thick and heavy rings? alloys that have a combination of grain reducers
and anti-oxidants. Research, research, research…

I’m in Iowa…

Jeffrey Everett

Attetntion Jeff and Bruce… Both of you sound like you are very knowledgable
and I think I could learn alot from your tips… Is there anyway of
contacting either of you? And where is it that you guys are from??? I am from
Pennsylvania near the Scranton area…I don’t suppose either of you guys do
any casting seminars… Do you? THanks for your responses and keep em’
coming…
Marc Williams

Handmade 18K and platinum gemstone jewelry. Fine die
and mold engraving. Diamond setting. Class rings/pins.
25 years experience in the jewelry trade. 515-472-9830


#10

Hi all,

I always read with great interest the discussions on casting,
both vacuum and centrifugal. I teach both methods in the studio
and have found excellent results are possible with both. My
studio percentage in casting success runs in the 95-100% range.
With that said, there are some things that I have noticed as
potential problems in a smaller (non-commercial) setting.

  1. Inadequate sprueing. I understand that in a small studio,
    the need exists to control costs, but undersprueing a wax to
    save on metal use often results in a missed casting, which
    results in higher labor costs and lower profits. A small
    commercial jewelry caster once told me that of all the problems
    he sees jewelers make in casting, the biggest by far is improper
    sprueing. He determined that it was because they did not want
    the extra metal in the sprues and button. Too small a sprue
    will often result in a missed casting or terrible metal quality
    in the casting. Peter Rowe has always made good points with
    regard to porosity (the caster’s nightmare), thank you Peter.

  2. Careful investing is essential to success in casting. My
    students never have incomplete castings if the sprues have been
    positioned correctly and flask and metal temperature are
    controlled. We do not have an extensive control system, but I
    do explain quite a bit about what should be happening.

The only blowouts I have seen in casting result from improper
investing or improper burn-out proceedures. Too little
investment over the model will undoubtedly result in the vacuum
pulling out the top, or the centrifuge blowing the metal through
it. Proper investment mixture will also insure a strong,
reliable mold. This is where our studio miscasts happen each
semester, even though I stress the importance of proper set-up,
mixture, and process. It only takes once for most students to
realize the need to pay attention to detail.

  1. Larger flasks, multiple pieces. I personally have the
    least experience in large, multiple, casting (30 or more
    objects), so I do not pretend to pass myself off as an expert
    here. While we do not concentrate on large production runs
    (most of our casting is 1-5 items per flask), I do believe that
    sprueing and temperature will control much of the problem. I
    believe Peter is correct when he comments on the pressure/weight
    of metal being poured. A foundry should have the same problem,
    but doesn’t because the effects of gravity are different with
    the larger amounts of metal being fed to the mold. I say this
    because now I offer my opinion.

I am more comfortable when a student is vacuum casting 3 or
more ounces of metal. Any problems that have arisen with metal
being sprayed (and I’ve had less than 10 in 19 years), resulted
from too much metal being forced into the flask too quickly.
This was the result of inadequate sprues in most cases, but a
problem non-the-less.

Please realize that I am instructing students who will probably
work in small studios where castings will not include larger
production runs, or in their own studios where the casting is
done on an as needed basis.

Yes, we still have porosity on some castings, and I always go
back through the process with the student to see what the causes
may be.

All this has been related to say that, I find both casting
processes beneficial and accurate. If I had to choose for
myself and could not afford to set-up both methods, I would
choose the vaccum. It offers me a greater range of use than I
comfortably find with the centrifuge.

Good Casting,

Tim Glotzbach
Eastern Kentucky University


#11

Hi Tim Glotzbach, I agree with your statements whole
heartedly… both Vacuum and centrifuge work well when the proper
process and procedures are followed. best wishes Daniel Grandi


#12

Dan and Edan You might get a laugh at this. About twenty years
ago I could only afford one caster, so I went with an Auquvac. I
believe it was made in Denver. It worked great. It worked on the
venturi method created by water running out of the tap as Dan was
saying. The only problem was that the water pressure was so bad
at certain times of the day that I could not use it at all. I
would be lucky to get 15" in an hour in the am, while everyone in
our neighborhood was showering. In the mid of the night I could
pull 25" in about 2 minutes. I lived in Denver. It still worked
for investing and casting, but slooow. So I solved the problem
with a five gallon bucket, a powerfull pump and some platic
tubing. I just recycled the water. I did not have to take in
account my neighbors personal habits after that.

Don Norris
@Donald_Norris
PO Box 2433 Estes Park, CO 80517


#13

Hmm,…can either Mr Grandi or Jagman explain '‘wax wash’? What
precisely is it, how is it used, and what precautions, limitations
are important to observe in it’s use? Thanks in advance!
Frif…


#14

I have been using a local caster and when I first started they
charged me for metal only. now they are also charging me and $25.
per crucible they use. is that the going rate? Thank you, Jill


#15

Hi Jill, That sounds like a bargain to me (as long as they aren’t
charging you a large percentage over spot for the metal). When I was
having my casting done by a casting shop 10 years ago, that is what
they were charging me per flask, as was anyone else doing casting (or
more), so a $25 fee today seems reasonable. John


#16
Now they are also charging me and $25. Per crucible they use. Is
that the going rate? 

$25.00 for the first piece $12.00 each additional in the same flask
is my and several others I’ve talked to.

ROBERT L. MARTIN
Gold Smith / Diamond Setter 
yukhan@aol.com