Bridge Second Skin Flow
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This setting adjusts the amount of material that is extruded to print the second layer of skin above a bridge.

Reducing the amount of material will effectively reduce the line width of the bottom side that is bridging a gap. With reduced line width, the lines' surface-to-mass ratio is greater, which allows them to cool down faster and this will prevent them from leaning as much on the first bridge layer.

However reducing the flow rate too much will cause a great change in the flow rate, especially when combined with a [slower printing speed](bridge_skin_speed_2.md). In reality the material will not be able to change its flow rates very quickly, which causes the lines to be somewhat thicker than intended as the flow rate is slowed down, and somewhat thinner than intended as the flow rate is sped up.

Also keep in mind that you'll most likely want the bottom side to be closed at some point, either to be water tight or just to look better. Having too many layers with a sparse infill creates deep crevices that could even extend into the infill pattern.