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Rasper's steps for alloying Silicon Bronze.
Posted: Thu Mar 03, 2016 12:32 pm
by Jammer
Silicon Bronze Ingot CDA 873 - Everdur
Composition Nominal
Copper 95
Silicon 4
Manganese 1
Physical Properties
Melting Point (Liquidus) 1790F
Melting Point (Solidus) 1590F
Pouring Temperature (Light) 2000-2150F
Pouring Temperature (Heavy) 1850-1950F
Density .302 lb/cu. in.
I melt a 1/3 crucible of Everdur and then start adding the copper to that and push it under the surface immediately to prevent air contact. After the crucible is 2/3 full I add some silicon and manganese. Then I add the remaining copper and then the remaining silicon and manganese.I let it sit for a few minutes and add some borax to the center of the melt and stir a bit with a steel rod. Then I pour it into ingots. I still get some dross doing it this way. The borax eliminates some of it.
The whole process takes maybe 20 minutes.
Re: Rasper's steps for alloying Silicon Bronze.
Posted: Fri Mar 04, 2016 11:59 pm
by mite5255
Jammer wrote:Silicon Bronze Ingot CDA 873 - Everdur
Composition Nominal
Copper 95
Silicon 4
Manganese 1
Physical Properties
Melting Point (Liquidus) 1790F
Melting Point (Solidus) 1590F
Pouring Temperature (Light) 2000-2150F
Pouring Temperature (Heavy) 1850-1950F
Density .302 lb/cu. in.
I melt a 1/3 crucible of Everdur and then start adding the copper to that and push it under the surface immediately to prevent air contact. After the crucible is 2/3 full I add some silicon and manganese. Then I add the remaining copper and then the remaining silicon and manganese.I let it sit for a few minutes and add some borax to the center of the melt and stir a bit with a steel rod. Then I pour it into ingots. I still get some dross doing it this way. The borax eliminates some of it.
The whole process takes maybe 20 minutes.
Hi Jerry, What thickness would you call thin
Re: Rasper's steps for alloying Silicon Bronze.
Posted: Sat Mar 05, 2016 9:55 am
by Jammer
Not sure mike, I got the chemistry from the net and this is Rasper's explanation on alloying. Maybe Richard will chime in, but I imagine that 2 to 4 mm would need to be pretty hot. It would also depend on the area. If you were casting a thin belt buckle or a large thin plaque. Taking into account how long it's going to take to fill the mold.
Re: Rasper's steps for alloying Silicon Bronze.
Posted: Sat Mar 05, 2016 5:09 pm
by Rasper
I pour my sculptures at between 3/16 and 1/4 inch thick (in Ozspeak between 5 and 6.5 mm). I pour at around 2000 F. (1100 Centigrade). Remember though that I am pouring into a mold that is hot (somewhere around 800 F. (425 centigrade). I am also limited by the mold composition: plaster does not behave well when metal over 2000 F. is poured into it. It causes surface problems such as this:
What you want is to pour bronze just hot enough to fill the mold completely. How does one determine that? By experience mostly. (That's code for making mistakes.)
Richard
Re: Rasper's steps for alloying Silicon Bronze.
Posted: Sat Mar 05, 2016 5:46 pm
by mite5255
Rasper wrote:I pour my sculptures at between 3/16 and 1/4 inch thick (in Ozspeak between 5 and 6.5 mm). I pour at around 2000 F. (1100 Centigrade). Remember though that I am pouring into a mold that is hot (somewhere around 800 F. (425 centigrade). I am also limited by the mold composition: plaster does not behave well when metal over 2000 F. is poured into it. It causes surface problems such as this:
What you want is to pour bronze just hot enough to fill the mold completely. How does one determine that? By experience mostly. (That's code for making mistakes.)
Richard
Thanks Richards, I do disagree with one statement tho, we don't make mistakes, we have learning experiences
