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Posted by John Stevenson on October 3, 2006, 7:16 am
Please log in for more thread options On Tue, 3 Oct 2006 12:03:32 +0100, "Andrew Mawson"
>
>> Andrew Mawson wrote:
>> > 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):
>> >
>> > http://www.srs-ltd.co.uk/products_services/eurovest.html
>> >
>> > 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
>> >
>> >
>> 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
>
>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
>
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.
Visit the new Model Engineering adverts page at:-
http://www.homeworkshop.org.uk/
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> item I have previously cast in bronze using the following investment
> casting plaster (which I still have a 50 lb bag of):
>
> http://www.srs-ltd.co.uk/products_services/eurovest.html
>
> 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
>
>