Bridge Third Skin Density
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This setting controls the density of the skin in the third layer above the bridge. At 100% density, the lines are placed directly adjacent. At lower densities, the lines are spaced further apart.

When spacing the skin lines directly adjacent to each other, they will stick to one another. This helps in making the model water tight and will look smoother on the underside of the print. It will also allow subsequent lines to lean on the previous lines a bit, which helps to prevent sagging.

However the material will not be able to cool as well. With some spacing in between the skin lines the air will be able to flow around the beads which significantly improves the rate at which they can cool and solidify. Of course, this only applies when the fan is turned on, so for high temperature materials this strategy is not going to work. The sagging effect is also reduced in the third layer because it can lean on the first and second layers, so other factors such as smoothness are more of a factor for this layer. Also consider that at some point, you'll probably want the bottom side to become completely closed in order to become water tight or have some sense of smoothness.

Which of these effects is stronger depends on the viscosity of the material, how fast it solidifies and on the fan speed. Some tuning is always required.

**If the [Bridge Third Skin Flow](bridge_skin_material_flow_3.md) is less than 100%, there will also be some spacing between the lines even if the density is 100%, because the lines will be thinner then.**