You can improve surface finish by applying back pressure.
Without applying back pressure, surface finish reveals open foam cells.
Drill holes into a board that can cover mold opening during casting.
Apply Ease Release™2831 to board. Pour foam into mold and place board over mold with holes centered over cavity.
Hold board firmly in place until foam stops rising. Let foam cure for 2 hours.
Use a scraping tool to remove excess foam.
Board is removed to reveal flat back of the casting.
Pressure uniformly compressed foam into mold detail resulting in better surface finish.