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Lost wax casting iron

I want to lost wax cast some small statuary in cast iron - this same item I have previously cast in bronze using the following investment casting plaster (which I still have a 50 lb bag of):

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I don't think that it'll take the higher temperature of cast iron (1550 deg C pouring temp as opposed to about 1200 for the bronze) so was considering using fine silica sand & sodium silicate both of which I have to hand.

Once the bulk of the wax is steamed out of a plaster investment it is then put in a burn out kiln to remove all traces of the wax and water, and I would have to do the same with the sodium silicated sand, but will this burn out the wax and leave a porous matrix as in the investment plaster ? Obviously any wax trapped in the mould could be potentially explosive when the iron enters so any informed opinions would be appreciated.

AWEM

Reply to
Andrew Mawson
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What you're proposing rather negates the purpose of lost wax casting, why not invest in the correct ceramic coating product? The improvement in finish over your "sand" casting could well be worth it. BTW, have you actually inquired as to the maximum working temp of your casting plaster?

Tom

Reply to
Tom

Since what you are doing is a sand/silicate/CO2 mould, it ought to behave in the way that they have since time began...

Not an informed-by-experience opinion. Just a supposition that If we used to be able to do it on medium speed diesel crank cases with foam masters, you ought to be able to do it with wax masters.

Mark Rand (must remember to stay North of the Thames :-) RTFM

Reply to
Mark Rand

Too right! Preferably upwind too...

Regards, Tony

Reply to
Tony Jeffree

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Tom,

The upper limit for the investment plaster is 1200 deg C and that's frankly pushing it. Above 700 deg C it begins to have problems with dissassociation but the metal tends to hold it in place. The ceramic shell slurries are available from people like Remet but in large quantity orders only. Hence proposing the use of a very fine (infact core) sand bound with sodium silicate, and my concern was the ability to burn out the residual wax.

AWEM

Reply to
Andrew Mawson

Got some drops we put in the dogs ears that remove wax, wonder if they will work. Can't see the dog being happy used as a test bed at 1200 degrees

-- Regards,

John Stevenson Nottingham, England.

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Reply to
John Stevenson

Down Bronzo.... He's not a ferrous-shus hound.

Joules

Reply to
Joules Beech

That's what you might call making a dog's ear of it...

Regards, Tony

Reply to
Tony Jeffree

Platinum melts at 1774 deg C so you could look at the jewellery plat investments if you can find them in the quantities you want.

Reply to
Andy

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Thanks for that Andy - I've decided to try to fine silica sand and sodium silicate route and keep my fingers crossed

AWEM

Reply to
Andrew Mawson

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