Pits and Blow Holes in Castings

We cast artware products of high quality mainly in zinc alloy. Our casting is of high quality but we do get pieces that are fine but ruined by just one visible pit or blow-hole. We rejects these pieces. Are there any such thing as a metal 'putty' which could fill the pits and later electroplated. We could save the rejected pieces if this was possible.

Mr , there is no putty as such for pit marks & hole , You just have to reject them & recycle them , or improve the composition of the raw material of casting.
There is no way to improve the surface of any casting components
Regards,

Blow hole issue comes due to moisture in sand.
Heat the sand to remove the moisture before moulding and then use this sand.

This point will help u.

there is no putty which can be electroplated later.blow holes in the castings (on surface ) are treated with welding & machining them thereafter.

only micro porosity in the castings can be corrected.the components which get rejected during pressure testing due to porosity can be corrected.