A method of injecting a liquid between a first panel and a second panel positioned flat against each other includes providing a tool defining an internal passageway having an inlet and an outlet. The first panel and the second panel are separated with the tool, to form a pocket between the first panel and the second panel, such that the outlet of the passageway is positioned in fluid communication with the pocket. A liquid source is connected to the inlet of the passageway to supply a liquid to the passageway. The liquid is injected into the pocket formed between the first panel and the second panel through the outlet of the passageway of the tool. The pocket is compressed or flattened to wet-out the liquid. The pocket may be compressed with the separating and injecting tool, or with a different device, such as a compressor or clamp.