Bridge Third Skin Speed
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This setting controls the printing speed of the skin lines in the third layer above the bridge.

For materials that require the fan to be turned on and turned up high (such as PLA), it is generally better to print bridges very slow. This allows the fans to blow a lot of air over the material, which causes them to solidify very quickly. The material doesn't get as much chance to sag then, which would make them lean on the first and second bridging layers and make those sag more. This is less effective for materials that don't need the fan to be spinning so fast or printers that don't have a very powerful fan.

Printing more slowly will also create a large change in the rate at which material needs to be extruded from the nozzle opening. This change in flow rate takes some time, which results in overextrusion when the print head slows down for the bridge and underextrusion afterwards. Since the third layer is less critical for overhang quality than the first two bridging layers, it is better to have the third layer printed at a speed closer to the ordinary [printing speed](../speed/speed_topbottom.md) to prevent over- and underextrusion.

In general it is better to print the bridging skin lines slowly with materials that print at cold temperatures, such as PLA. It is better to print the bridging skin lines around the same speed as the ordinary top/bottom speed when printing with high-temperature materials such as polycarbonate.