Abstract: A method is described for filling narrow gaps in a surface that is being overcoated. This has been achieved by heating the overcoating layer to a sufficient extent so that it flows relatively easily. This, in combination with externally applied pressure, causes the overcoating layer to effectively fill any narrow gaps in the surface being coated. Temperature and pressure are applied for a time that is sufficient to allow small quantities of gas that may have become trapped in the gaps to bubble to the surface. In an alternative embodiment, the surface to be coated is subjected to negative pressure prior to application of the coating. This eliminates the possibility of trapping gas in the gaps so a waiting time is no longer necessary.