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Lost wax, lost casting


#1

I have a problem with a mans signet ring that I’m putting together. The
body of the ring is in red injection wax. The top which is approx. 2mm
thick is in green carving wax. I have put the two together and cast as one
piece, sprue being on the bottom of the shank.
I must be missing something here for I would think that red wax has a
lower melting temp. than green. But what appears to be happening is the
green wax is causing investment breakdown.
Other castings with the same batch of investment came out fine, so that
does’nt seem to be it.
The ring being cast is approx. 15 grams with no fine detail to really
speak of.
I’m going to try again only this time running wires to the top portion of
the ring, hopefully this will help in drainage.
I’ve tried this once quite a while back and basicly had the same problem.
Any suggestions would be appreciated.

Michael in NC


#2

I would steam dewax it first, that should help the with the breakdown
problem. Then cast as usaul.The green wax is made with a petrolium based
wax most likely, only guessing but have had similer problems. Also make
the sprue bigger, ie, larger gauge. Hope this helps.

Matt the Catt @ Contemporary Industrial Arts


#3

But what appears to be happening is thegreen wax is causing investment
breakdown

Michael:

To better understand the situation, could you please include the following
data:

  1. Metal temperature
  2. Mold temperature
  3. Time the mold is at temperature before pouring

Lee


#4

Have had about the same thing go on with some of my stuff and I put
small vent sprues on the top and a large vet to the out side from the
center of the ring, this one dose not touch the ring or gets any metal to
it but is used to vent the gases out. ( One end of this sprue is attached
to the rubber sprue base about 1/2 in. from the button so when the metal
is cast it dose not get any, the other end is suspended in the center
where the finger goes) It is hard to explain but it works. If you have any
problems with this give me an E-mail and will send you a scan showing
this.

JB…


#5

I think your problem is the green wax expands and contracts ALOT with
change in temperatures. The green wax is expanding and cracking your
investment before it gets liquid enough to flow out. R&R (using thier
Duntuply{spelling??}) suggested that we put in a “fresh” 2 hour old can in
a pre heated 700 F oven. Works ok but sometimes still a bit of flash but
livable. Before KERR changed their investment formula 10 or so years ago,
Cynthia put fresh, (2 hour set) cans in a preheated 1200 F oven and it
worked great with green carvex (Filo) wax but they changed the investment
formula and the new stuff was/is terrible used this way.

One other thing that you can do to get away from the Carvex wax problem,
is make a mold of the carvex wax piece and inject the piece used for
casting. Have to use an RTV mold material, don’t heat vulcanize it!!!

Hope this gets you off of the hook.

John

John and Cynthia/MidLife Crisis Enterprises
Maiden Metals/C. T. Designs/ Bloomin’ Wax Works. etc.

PO Bx 44, Philo
CA 95466
Ph 707-895-2635 FAX 707-895-9332

The playfulness of the Universe
is reflected in the dance of the stars!


#6

hi michael,

the injection wax does melt at a lower temp than a green carving wax, but
i’m guessing wax elimination is not your problem. neither is investment
breakdown, as long as you are not exceeding 1350 f.

where i guess the problem lies is… is that the two pieces of green and
red wax are not adhered together well in an air tight way. if investment
can find a way between the two parts, it will. when one puts the two part
wax under vacuum while investing, the investment gets sucked between the
layers of wax. this leaves a pastry thin wall of investment (or just a
bunch of investment floating around in that specific area) that breaks
loose when the onslaught of gold rushes in.

best regards,

geo fox


#7

I would steam dewax it first, that should help the with the breakdown
problem. Then cast as usaul.The green wax is made with a petrolium based
wax most likely, only guessing but have had similer problems. Also make
the sprue bigger, ie, larger gauge.

Hi Matt & Others with Green wax Problem, It took me a while to figure out
what was happening with hard carving wax. I was having problem with the
surface on purple and blue wax as well. I talked to the folks at Kerr and
Kindt & Collins. They didn’t help much. Here’s what I discovered. You
don’t need to steam de-wax. The problem comes from steam building up
between the wax and the unmelted wax. Remember hard carrving wax melts at
a much higher temp. The steam will scrub against the investment and cause
a foul surface on your casting. So…Set your kiln at 200F (water boils at
212F, right?) let the flask dry out at that temp for four hours before the
rest of the burn out. Try it, you’ll be happy with the results. J.A.


#8

John Henkle is absolutely correct in his technique in drying out the
flask for a few hours BELOW the boiling point of water. Too many books say
to put the flask in an oven of 250 degrees or more. Been there-did that.
Bill Reidsema_


#9

Flask should sit after investing for 24hours(referred), then 50 degrees at
1hr, 500 at 20min, then to 1250… turn flask (started with metal pour
side up) for 30 min, turn over flask, start down to… for vacuum
casting, 850-900… silicon pat break up at 900ish… prefer 875!!!..

Jim


#10

John Henkle is absolutely correct in his technique in drying out the
flask for a few hours BELOW the boiling point of water. Too many books
say to put the flask in an oven of 250 degrees or more.

This would be true for most casting waxes, but for the Filo wax, it will
break the investment if heated this way as this wax is “VERY” expansive
when heated. If I remember correctly, this thread was started with a
statement of “a combination of green and other waxes being used” on the
item in question. It was never clear WHAT green wax was used, but if it
is the Filo wax, it is difficult to cast (many houses will not touch it)
but it’s hardness allows for very sharp, clean lines to be incorporated
into pieces. It is a carvers delight especially if one likes sharp,
straight abd clean lines!! Can be worked to a knife edge and it holds it.

Great thread, I have a few new ideas to try in the future…

John

John and Cynthia/MidLife Crisis Enterprises
Maiden Metals/C. T. Designs/ Bloomin’ Wax Works. etc.

PO Bx 44, Philo
CA 95466
Ph 707-895-2635 FAX 707-895-9332

The playfulness of the Universe
is reflected in the dance of the stars!


#11

Flask should sit after investing for 24hours(referred), then 50 degrees
at 1hr, 500 at 20min, then to 1250… turn flask (started with metal
pour side up) for 30 min, turn over flask, start down to… for
vacuum casting, 850-900… silicon pat break up at 900ish… prefer

Hi Jim,
You can’t be serious!?! Are these temps in Centigrade or Fahrenheit?? If
it’s Fahrenheit, what if your room temp is 70 degrees? Do you put it in
your fridge? Maybe I missed something or this this just proves how
forgiving investment is. Sounds pretty whacky to me. Does anybody else
think so? J.A.


#12

How bout we take out the first 50 F, and start to 500F, sit at 500 for 1/2
to hr, then on to 1250, over, for 1/2 hr, then down to 850/900…
better???

Picky, Picky, picky…

He,he . . . sorry bout the first 50F
Jim


#13

200, 400, 800, invert, 1200, then 1350. It takes at least 1 hour for the
inside flask temp to be what you want. Just because the kiln and the
paromiter(misspelled) is at a temp the inside temp will not be that unless
it has been in that environment for at least 1 hour… 200? for 1 hour,
that means when the kiln gets to 200? then start the timer then after that
400? and so on and so forth. After 1350? (Kerr satin Cast) back it down to
desired temp for casting… I like what I heard about the drying out at the
beginning of the burn out, letting it start out at 200? for a longer time.
I have also found the better the burn out is the better your castings are
going to be. Would also suggest that you, if you have the time, leave the
flasks at the different temps for a longer time , lets say up to maybe 2
or 3 hours. Play with it to find out what works best for what you are
doing. I have done burnouts that only took 1 1/2 hours and some that took
24 hours. Guess which one was the easiest to finish??? When you burnout
different kinds of plastic you will have to change things around but it is
all in the burnout. Go to toy store and get small plastic stuff and cast
it, it is a fun thing to do if you have the time…

JB


#14

I may not know the original question but if you are casting
sterling silver or any karat gold 24 hours is way to long to let
your flask sit before you start a burn out. You DO NOT want it to
dry out completly. Just my two cents and 15 years of knowledge.
Matt the Catt


#15

Can you put the flasks in a refridgerator sealed in plastic to
help slow the drying process??Marjorie Lord Australia


#16

Hello Marjorie, Wrap the flasks in a wet towel. Tom Arnold


#17
Can you put the flasks in a refridgerator sealed in plastic to
help slow the drying process?

Yes in deed you can. Ziplock bags are very useful for
refrigerating invested flasks. Squeeze the air out…zip it
shut and pop it in the frig, can safely hold for a week.


#18
Can you put the flasks in a refridgerator sealed in plastic to
help slow the drying process?

Hi Marjorie, Refridgeration should not be necessary. I have left
a flask over the weekend and then submerged it in water for 10
minutes and had good casting. J.A.


#19
Can you put the flasks in a refridgerator sealed in plastic to
help slow the drying process?

NO. if you can not cast right a way, let it dry you can let go
for weekend. come monday soke for 30 min.let stand for 30 min.
then fire. best to do right a way. cool times 10,000 lakes.


#20

Can you put the flasks in a refridgerator sealed in plastic to
help slow the drying process?

Think the drying process is there to remove surplus water from
the form to insure that it will not crack due to the water…
the other end (1250, etc. degrees) is a matter of heat and
cracking due to the sulfur content of the investment !!!..
HELP!!!

Jim