The trend now is to inoculate by placing pellets or granulated inoculant in the pouring cup, in the sprue, in an enlarged chamber in the sprue base
or by a cored wire containing an inoculant that is fed continuously into the sprue during pouring.
This is the least desirable sprue design, but the use of a choke core at the bottom of the reverse tapered downsprue or the reduction of runner cross section next to the sprue base
can partially overcome this disadvantage.
The cross-sectional area of ingates is typically 2-4 times greater than the sprue base
. This enlargement makes the nonpressurized system very useful in reducing the reoxidation of sensitive alloys entering the mold.