A needle assembly for a liquid applicator comprises housing with longitudinal channel. The channel comprises upper and lower open ends. A needle bundle is movably mounted in the channel, which comprises needle shaft and needles attached thereto. A biasing member is configured and mounted for (i) biasing the needle bundle longitudinally towards a retracted position and (ii) biasing the needles laterally towards a needle-guiding side wall of the housing adjacent the lower open end. The biasing member is configured and mounted to form a fluid seal between the lower and upper open ends. The biasing member comprises an elastic tubular section with opposite sides. The first side has a first rectified length. The second side has a second rectified length longer than the first rectified length so that the second side is less tensioned than the first side to bias the needles towards the needle-guiding side wall.