First off - I regret that I'm starting all these new threads, on the
same topic, but when I try to "Reply to message" it takes me to a new
thread window... But that's NOT what I want to say!!!

Thanks for the various suggestions...

I do want to follow-up on a couple of the responses...

Degassing/Flux solution & Porosity due to Excessive melt Temps...

I have come to understand that Degassing agents & Flux agents are
essentially the same thing is this true? Also the idea that I can have
the slag/dross precipitate into a dry powder on top of the melt sounds
very desirable as I typically skim a pound or more of slag with good
material melted in per melt.

I'm slowly getting the idea that Chlorine is the active ingredient, or
is it sodium (I will go back and re-read the reply's one more time)...
The supplies that I have coming from www.smelko.com essentially were
thrown in for free along with the Petro-Bond order. I'll try some
comparisons on a pot per pot basis to assay the difference between the
commercial product vs a readily available substitute... Though Smelko
sells the degasser for about $1.50/lb CDN.

Also, any additional info on the "water glass (solution of sodium
silicate)" would be greatly appreciated as I've never heard of this
process. In the mean time I'll google on both water glass & sodium
silicate, to get somewhat upto speed.

Lastly, my gut feeling is that porosity (pitting or bubbles in the
solidified pattern) is due to pouring the metal too hot. Or is it a
result of bringing the metal to high in temp and would result in the
pour regardless of the pouring temp once the temp threshold has been
exceeded in the initial melting temp???

Thanks for all the info!!!

Frank
www.theworkshop.ca

I have come to understand that Degassing agents & Flux agents are
essentially the same thing is this true? Also the idea that I can
have
the slag/dross precipitate into a dry powder on top of the melt
sounds
very desirable as I typically skim a pound or more of slag with good
material melted in per melt.
Only in that these tend to be chlorine compounds which combine with the
hydrogen in the molten aluminium. Flux protects the molten metal by
floting on top and helping contaminates separate out in either the
bottom of the pot or in the slag/dross layer on top. The degasser
liberates quantities of chlorine that combines with the hydrogen to
make hydrogen chloride that comes off the melt as white smoke.

I'm slowly getting the idea that Chlorine is the active ingredient,
or
is it sodium (I will go back and re-read the reply's one more
time)...
The supplies that I have coming from www.smelko.com essentially were
thrown in for free along with the Petro-Bond order. I'll try some
comparisons on a pot per pot basis to assay the difference between
the
commercial product vs a readily available substitute... Though Smelko
sells the degasser for about $1.50/lb CDN.

Also, any additional info on the "water glass (solution of sodium
silicate)" would be greatly appreciated as I've never heard of this
process. In the mean time I'll google on both water glass & sodium
silicate, to get somewhat upto speed.
Sodium silicate is sold as an adhesive. Most anything that is heat
resistant can be used. Some people use dry wall compound. You can
sand your foam patterns smooth and although I have never tried it, I
have heard that you can paint the patterns with latex paint to fill in
the pores in the plastic foam, before you coat with refactory. Also
you might want to try different foam materials. I get different
results from regular insulation bats, the blue foam bats and the much
finer foam used as packing material and cheap ice chests.

Lastly, my gut feeling is that porosity (pitting or bubbles in the
solidified pattern) is due to pouring the metal too hot. Or is it a
result of bringing the metal to high in temp and would result in the
pour regardless of the pouring temp once the temp threshold has been
exceeded in the initial melting temp???
If you have not done so already, check http://www.lindsaybks.com for
their foundry books. Their reprint of the Navy foundry manual is
invaluable and I used it as the text in our foundry class. The other
books on pattern making and foundry work are reprints of manuals for
the old manual methods which is exactly what we are looking for.
Chastains series is also very good. Gingerys books are for the cheap
at heart (like me.) When you read the old books and look at what these
people managed to make, it is clear that while modern equipment is very
helpful, extraordinary work can be produced with the simplest of
materials. As my Dad used to tell me -- its a poor workman that blaims
his tools! While a mixture of potassium and sodium chloride does melt
at a lower temperature, I found that when the melt was just hot enough
to melt regular salt, by the time I got it out of the furnace and was
ready to pour it had cooled to about the right temp. Also the sub-zero
deicing compound that many stores sell in place of rock salt is
potassium chloride. Never tried it as canning salt worked for me, but
it is cheap enough. Also avoid splashing when pouring. You can entrap
air.

Thanks for all the info!!!

Frank
www.theworkshop.ca

ready to pour it had cooled to about the right temp. Also the sub-zero
deicing compound that many stores sell in place of rock salt is
potassium chloride. Never tried it as canning salt worked for me, but

Most I've seen are calcium chloride, so check the label before buying.

--
Cats, Coffee, Chocolate...vices to live by