Help on Holes on polyurethane film

[Beorges]

Team we are working on the making of polyurethane rubber, injected molded in the form of pads.

but we have started seen some holes very small after molding,

we clean the mold and there is no dirt, temperatures and presure have been remain the same.

What can be causing this aside processing? something in the material? mixing of the material? chemical imbalance?

Thanks