Bronze not flowing into mold

I’ve been practicing lost wax steam casting in scrap silver for
practice with varying degrees of success. When doing so, I use an 8
gauge sprue wire with a center split cut into it where it meets the
button, in order to utilize surface tension to keep my silver from
flowing until I hit with my steam caster, and it works pretty well.

Last night I tried to cast virgin white bronze into 2 of my mold and
got no metal flow into either mold. None. Would this be due to
silver flowing thinner and quicker than bronze, and the sprue holes
in my flask being too small? I burnt out at 1200F for 3 hours and
there was no discoloration on the sprue button lining, and I cast at
with my flask just barely over 900F.


I’ve been casing bronze with the lost wax process for close to 20
years now. My investments are straight out of the kiln hot and I pour
silicon bronze at temperatures between 1800F and 2100F. Also, if your
sprues are too long the metal will cool and you will get a pour cast.