You can make mold locks the size of the Rock of Gibraltar and still
have mold lines, sound familiar? One good way to reduce mold lines in
injected waxes is to make sure that the final cuts to the model are
parallel to the mold. If the cut lines around the model slope up or
down, any pressure on the mold will cause the 2 surfaces to slip a
little past each other. The flatter the surfaces next to the model,
the less the slippage.
– Spike Cornelius Portland, Or. RC ArtMetal