A shoe sole portion painting system comprising: a paint assembly comprising at least a spray nozzle having a front port and a back port, the spray nozzle adapted to emit a liquid material via the front port, wherein a hypothetical axis extends from the back port through the front port in an intended direction of the liquid material flow from the front port; and a masking assembly comprising: a mask cover coupled to the paint assembly, the mask cover positioned in front of the front port of the spray nozzle such that the mask cover is effective to partially obstruct the liquid material intended to be emitted by the spray nozzle, the mask cover having an inward-facing surface and an outward-facing surface, wherein an aperture extends from the outward-facing surface through the inward-facing surface, and wherein the aperture is positioned on the mask cover such that the hypothetical axis extending from the back port of the spray nozzle through the front port of the spray nozzle extends through the aperture such that a portion of the liquid material intended to be emitted by the spray nozzle is able to be transmitted through the aperture; and an air knife coupled to the mask cover and adapted to emit a laminar fluid flow in a generally angled direction towards the direction of the hypothetical axis extending from the back port of the spray nozzle through the front port of the spray nozzle. a paint assembly comprising at least a spray nozzle having a front port and a back port, the spray nozzle adapted to emit a liquid material via the front port, wherein a hypothetical axis extends from the back port through the front port in an intended direction of the liquid material flow from the front port; and a masking assembly comprising: a mask cover coupled to the paint assembly, the mask cover positioned in front of the front port of the spray nozzle such that the mask cover is effective to partially obstruct the liquid material intended to be emitted by the spray nozzle, the mask cover having an inward-facing surface and an outward-facing surface, wherein an aperture extends from the outward-facing surface through the inward-facing surface, and wherein the aperture is positioned on the mask cover such that the hypothetical axis extending from the back port of the spray nozzle through the front port of the spray nozzle extends through the aperture such that a portion of the liquid material intended to be emitted by the spray nozzle is able to be transmitted through the aperture; and an air knife coupled to the mask cover and adapted to emit a laminar fluid flow in a generally angled direction towards the direction of the hypothetical axis extending from the back port of the spray nozzle through the front port of the spray nozzle. a mask cover coupled to the paint assembly, the mask cover positioned in front of the front port of the spray nozzle such that the mask cover is effective to partially obstruct the liquid material intended to be emitted by the spray nozzle, the mask cover having an inward-facing surface and an outward-facing surface, wherein an aperture extends from the outward-facing surface through the inward-facing surface, and wherein the aperture is positioned on the mask cover such that the hypothetical axis extending from the back port of the spray nozzle through the front port of the spray nozzle extends through the aperture such that a portion of the liquid material intended to be emitted by the spray nozzle is able to be transmitted through the aperture; and an air knife coupled to the mask cover and adapted to emit a laminar fluid flow in a generally angled direction towards the direction of the hypothetical axis extending from the back port of the spray nozzle through the front port of the spray nozzle.