Platinum casters [Was: Centrifugal people ]

Skip, I have seen the oval flasks, they look pretty cool. As for
the tapered flasks that also sounds good. Instead of flask
liners, I use a heavy coat of refridgerated vaseline on the
inside of my flasks. This not only makes removal easy, it
provides the expansion space necessary (and it’s cheap!). A note
of CAUTION here: Be sure to wear long heat proof gloves when you
put a flask like this (with vaseline) into a hot oven…it can
ignite rather quickly! Also I have a water blast cabinet that
helps a lot in removing investment. I don’t want nasty acids in
my shop. I have some employees and don’t need extra safety
hazards like hydofloric around. You mentioned bubbles in your
investment…do you use a wax wash? Also I have a flat sanding
board that I dress the end of the flask that will be in touch
with the vac pad on the vacu-veast container. Makes for excellent
vac. Have you tried “Impulse”? It comes in pre-weighed
packets…that makes it very convenient. I assume other dental
products come that way as well. I wet the investment for 30 sec
before mix. With the amount of work I have to do at any given
time, I admit I’m looking for the most expediant proceedure that
does not compromise the quality. J.A.

Skip or John (withoutthe “c”) or anyone:

I’m following, as best I can, being about to cast my first
silver in a perf machine, your threads on casting. Sounds like a
great convenience to not have to wait for the investment to cure
overnight. My question is, can I use the platinum investments to
do silver/gold and do I have to use a vacuum whipper or some
such, or can I just use my old portable kitchen mixer on this
kind of investment and proceed as I would for other types of
investment (R&R, etc.), that is, mix, vacuum, pour into flasks,
vac again, wait for gloss over, scrape, put directly in the kiln?

Hi Jess,

Yes I suppose that you can, but a kitchen mixer is made to
incorporate air into the mix. Kinda self defeating if you ask
me. I cast gold and silver into Jelenko Complete as well as the
high heat metals(I don’t cast Platinum). Be sure not to mix too
long and have everything layed out so you don’t waste any time.
Don’t forget to refrigerate tha liquid and the investment along
with the mixing bowl. You will buy yourself a bit of time doing
this.

Regards,

Skip

                                  Skip Meister
                                NRA Endowment and
                                   Instructor
                                @Skip_Meister
                                10/11/9700:56:00

Skip Not only that, Platinum investment is acid based…so it is
possible that the mixing paddles of the Kitchen mixer will start
to dissolve somewhat and that will lead to contamination down the
road. For Gold and Silver, use a regular gypsum type investment.
It is cheep and designed for that.If you mix Platinum investment,
you can get Tungsten sputtered paddles for the industrial mixers.
That eliminates the problem. Good luck.

PGI USA, Jurgen J. Maerz, Mgr. of Tech. Edu.

Hallo Jurgen,

The high heat investment of which I am speaking is made for
gold. In dentistry, one of the metals that we use is a gold
called SMG-2 (Super Micro Grain) it is an alloy of 87% gold 7%
platinum and 6% of other metals. Another is a
palladium/silver/gold alloy and this investment is made for
these type of metals. These metals have casting temps of 2400
deg. F and 2550 deg. F respectively. I don’t know what temp.
you cast platinum at. I do know that the burnout appears to be
acidic because it can corrode the surroundings, so a hood and a
powerful vent fan are imperative. I use this investment for
dental high(to be veneered with ceramic) and low heat(solid gold
work) golds, jewelry gold and silver. I guess I need to get
some litmus paper and test it.

Regards,

skip

                                  Skip Meister
                                NRA Endowment and
                                   Instructor
                                @Skip_Meister
                                10/12/9702:18:48

Greetings Jess and all; I have been using a kitchen mixer for
investment mixing for about 5 years now and with very good
results. I purchased it at a flea market for $3. It had only one
blade and the owner expected that no one would have a use for it
that way but I prefer it with just the one. It is a hand held
model. Any bubbles created are easily pulled out.

                                   Darryl