A barn curtain having a transparent panel and a non-transparent panel is prepared by a welding machine. The welding machine has an inner heater assembly including a first roller wheel, an inner plate assembly having a lower inner plate and an upper inner plate spaced apart from the lower inner plate in a vertical direction, and a heater, and a first roller assembly including a second roller wheel aligned with the first roller wheel. A side of a transparent panel is fed through the lower inner plate and a side of a non-transparent panel is fed through the upper inner plate. The plates are heated with the heater to partially melt the side of the transparent panel and the side of the non-transparent panel. The side of the transparent panel and the side of the non-transparent panel are pressed between the roller wheels and joined.
