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Old May 29, 2019, 08:20 AM   #2
HiBC
Senior Member
 
Join Date: November 13, 2006
Posts: 6,300
I used to work for a brass/bronze foundry in Northern Colorado. Actually,art casting sculpture is pretty big around here.

But that s mostly lost wax.The outfit I worked with also did high resolution,very fine sand casting. The sand was "Trade Secret" .It supposedly came from some river in Missouri. A lot of the business was replicating antique hardware.Cash registers,furnture and door hardware,etc. The could replicate old brothel tokens and the detail was very good.

I ran the furnace,loaded the crucible,watched the melt,Helped pour,cut sprues,filed,etc.
Every chance I'd get,I'd prefer silicon bronze over brass for material.

I'd put a square of common cardboard under the crucible n the furnace (gas flame off) This would turn to ash and kept the crucible from sticking.
Then I'd load the crucible with the metal f choice.
A problem with brass is the zinc catches fire and burns at casting temp.
We added a couple of beer bottles to the crucible...obviously before the metal was melted. Not a drop of moisture can go into the melt! The glass melted and put a cap on top of the brass.This kept the oxygen out,fo the zinc did not burn.
At the moment of pour,we'd pierce the molten glass with a poker for a hole to pour through.

The pour burns,smokes badly ,and is undoubtedly horrible for health.We opened the garage door,ran fans,and wore respirators.

We did get very good results.

This was maybe early 80's? I forget some things. I'm pretty sure with bronze and aluminum we did a flux/skim,but with brass,I don't think so. That glass cap was important.

I hope I told you at least one thing you did not already know.
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